Why does the load bank trip during 0-100 load step, and what is the possible solution? What can be done with the load-bank fans to assist?
This is a common problem because the Loadbank has an under-voltage relay that trips at 100%. Go to 95% instead. Or run the Loadbank on a separate power supply for fans.
What is also known as a static switch and on what equipment type, and what is its function?
Static bypass¹, sometimes referred to as this, found in a UPS. The UPS may be equipped with a bypass. In the bypass mode, If one of the UPS functions fails, the load can be transferred to the bypass AC input (supplied with utility or standby power, depending on the installation).²
Source ¹,² How UPS (Uninterruptible Power Supply) Systems Works ~ Learning Electrical Engineering (electricalengineeringtoolbox.com)
When setting up a UPS for testing there is the input, bypass, output top to bottom. We would want what on the bypass?
1 x CT across one phase for measuring transient current when UPS is in bypass (static bypass).
What would be a UPS in passive standby mode?
The inverter is connected in parallel with the AC input in this mode.
When connecting the UPS output and bypass source to the external Maintenance Bypass Switch (MBS), why would there be a bumpless transfer to the bypass input?
the same phase relationship must be observed since a UPS’ output will synchronize with Phase L1 of its bypass input source. Maintaining this phase relationship will result in a transparent bumpless transfer between sources.
Source: UPS 101 Knowledgebase - UPS Voltage and Phasing Guidelines (ltipowersystems.com)
What is a line-interactive UPS? Of the 3 modes: on-line, off-line, and line interactive.
This type of UPS is a type of uninterruptible power supply (UPS) that has an inverter in line with the AC input. It maintains the inverter in line and redirects the battery’s DC current path from the normal charging mode to supplying current when power is lost.
UPS operational modes. The static switch’s role relates to the three operational modes for UPS systems which are?
A line-interactive UPS is a type of uninterruptible power supply (UPS) that has an inverter in line with the AC input. It maintains the inverter in line and redirects the battery’s DC current path from the normal charging mode to supplying current when power is lost
‘on-line’,
‘off-line’
‘line-interactive’. are all related to this type of switch.
Source: Understanding the role of static switches - Kohler Uninterruptible Power (kohler-ups.co.uk)
The static switch has two operational states. What are they?
– ‘On UPS’ and ‘On Bypass’ are these two states for this part of a UPS.
Source: Understanding the role of static switches - Kohler Uninterruptible Power (kohler-ups.co.uk)
What is another term for the static switch on a UPS?
Static bypass is another term for this type of switch.
Source: How UPS (Uninterruptible Power Supply) Systems Works ~ Learning Electrical Engineering (electricalengineeringtoolbox.com)
When hooking up a UPS we need the following points for testing concerning CT's and clamps? A bonus is on the bypass how many of the phases need to be tested?
we use bypass CT's and the outputs are only normal and bypass for voltage clips. No bypass for voltage.
1. DC voltage
2. DC amperage (clamp on across a couple of DC cables)
3. Input CTs
4. Bypass CTs (1 of the phases)
5. Output CTs.
6. Input voltage clips.
7. Output voltage clips.
A KTS is a device used to test a UPS?
False
A data Q is. The KTS is software.
When using CXware(c) to record you click on what prior to the button for record?
Click on tests and record.
When testing the sequence for transients on a UPS (single or double) what should you do with the Loadbank operator?
The LB operator gets a list of transient testing and is instructed to move at 15 second intervals through the transients; while on step 1 recording. This is the testing sequence for this.
When doing a UPS battery discharge test. What starts it?
To discharge the batteries you need to simulate a real world load drop
Open the MIB MCB (Maintenance isolation breaker-main circuit breaker).
explanatory: MIB or MIS stands for maintenance isolation breaker¹,² It is in series with the UPS output, isolating the UPS output bus from load power. MBP stands for maintenance bypass breaker. It wraps around the UPS power conversion circuits, providing power to the critical load while the UPS is being serviced.
Source¹: Recommended use of LSIG-equipped circuit breakers in UPS applications (eaton.com)
Source²: Safety (upsbypass.com)
The generator is reset at the EMCP (electronic manual control panel). Thus, what is a good thing to check every time after this is done?
Make sure the generator is in AUTOafter this is done, so that any run signals are evident from elsewhere. For example, a changeover PLC (program logic controller) may provide signals for start the generator.
When first testing a UPS transfer for a generator, what would be the best option. For example UPS prior to a PLC test.
Put the PLC in gen modemanual and then start. Then open the utility and then close the gen breaker MCBG (main circuit breaker generator) at USB (utility switch board) when the generator is up to speed.
Note: the gen speed is typically in under 10 seconds to full run and back down to the speed to settle in. 1500RPM for 50HZ and typically 1800RPM for 60HZ.
What is the formula for finding frequency on a generator when you know the RPM and the number of poles.
= RPM × number of poles/ 120 is the formula for this. For example: 1500 x 4 / 120 = 50.
source: 2016-09-27-2-Generator-Basics-1 (saved to files) web: Microsoft PowerPoint - 2. Generator Basics IEEE
Most modern, larger generators have a stationary________ with a rotating current-carrying conductor called____________. In other words what is stationary in a generator and what is the rotating current carrying conductor?
armature (stator) is stationary
rotor is the rotating revolving fieldconductor.
source: 2016-09-27-2-Generator-Basics-1 (saved to files) web: Microsoft PowerPoint - 2. Generator Basics IEEE
What are the two frequencies used in North America to get a generator to run at 60HZ?
Engine speed is the same as RPM, and to produce a 60Hz frequency, most generators will operate at an RPM of 1800 (4 pole) or 3600 (two pole & smaller).
Source: What Rpm Does A Generator Run At (Generator Speed, And Power Output) - Energy Answers
What is the purpose of damper bars in a generator?
This is used to reduce the winding oscillation.¹ Winding oscillation in generators is a phenomenon that occurs when the generator’s rotor experiences an unbalanced magnetic pull due to the interaction between the rotor’s magnetic field and the stator’s magnetic field.² This unbalanced magnetic pull causes the rotor to oscillate or vibrate.
source¹: Main Purpose of Damper Winding in Generator | Electrical4u
source²: Vibration-powered generator - Wikipedia
When doing steady states on a UPS what must we remember to do regarding the system that is providing the power and what is this called?
When doing this test on a UPS, one must remember not to be on the generator power: called compatibility testing.
SLIG (long time, short time, instantaneous, ground) -equipped circuit breakers are often required by code in the application of larger UPS systems. Specifically, UPS systems fed by 480 volts (up to 1000V) and protected by circuit breakers of 1000 amps or greater, must generally have ____________ in the service or feeder for that UPS
Example spec: Provide fault detection such that if an AC phase-to-ground fault occurs on the output of the UPS while the UPS is on battery, the UPS shall detect the fault and provide alerts and responses as follows
a means of ground fault protection is required for this type of equipment when the circuit breaker is 1000A or greater in the service that feeds this type of equipment.
source: Recommended use of LSIG-equipped circuit breakers in UPS applications, Eaton White Paper, Dec. 2019 WP153024EN
During system level testing with a 1000KVA UPS on generator power, what can we expect to see the UPS do during this test? The system lineup is 13.8KV, 3840KW/4800KVA per generator.
We can expect to see a UPS go to battery during this test. The generator is a sponge. One 1000KVA UPS is a small load less than 50% for the gen. More will go to battery during step load.
In a UPS, because power is equal to voltage times current, a degraded voltage from a single module or phase means?
In this type of equipment, other modules or phases must produce more current to accommodate the voltage drop because of this.
source: John E. Diamond, How to Maintain and Test UPS Systems _ EC&M March 1st 2001
You should test harmonicson a UPS at the following?
input & output voltage,
input and output current.
these are the two items we check when we test a UPS for this.
source: John E. Diamond, How to Maintain and Test UPS Systems _ EC&M March 1st 2001
What is total harmonic distortion (THD) and on what type of equipment is this checked?
Consider a crest factor of 1.4 is good but with mechanical load VFD's downstream more current can be needed.
___________ _________ _______ is essentially a measure of deviation from a perfect sinusoidal wave. (on a UPS) A load with high _____ requires more energy to sustain than a unit with low ________. The wasted energy dissipates as heat. Although inefficient, a UPS operating with high ______ at low load is in no danger of damaging conduction components. A UPS operating with high ____ at high load is extremely taxed because the unit produces energy to sustain the load along with additional heating.
source: John E. Diamond, How to Maintain and Test UPS Systems _ EC&M March 1st 2001
You should monitor the input and output of the UPS for harmonic current during the.
steady-state load test. Observing the harmonic content at 0%, 50%, and 100% load allows you to determine the effectiveness of the input and output filters. It is important to note that most manufacturers design UPS filtering systems for the greatest efficiency at full load. Consequently, the harmonic distortion is greatest when the system is least loaded and smoothes out as load increases.
²
source¹: John E. Diamond, How to Maintain and Test UPS Systems _ EC&M March 1st 2001
Source²: Power Factor Correction (PFC) – Understanding International Regulations - Power Electronics Talks
When loading a UPS at 100% what is preferred for load?
95% is preferred for this load for this equipment..
Note: this is unique to one company in the risk assessment and commissioning of systems business and may be 80% as required by the vendor. An agent should always consult the design references to ensure this test is correctly loaded as usually found in DIV 26 of the electrical specification for testing and commissioning.
The purpose of this testing is to demonstrate the transient response of the UPS module. This is done with what 2 tests?
step load and bypass loss transient tests demonstrate this type of response.
source: Joseph Ong, UPS Testing for Reliable Backup Power _ EC&M, Feb 1 2008
This is done to verify that the UPS system can operate at the rated load under ambient room temperature conditions. The procedure here is to load the UPS to rated load and operate it from 8 hours to 24 hours, depending on contractual requirements. (specifications)
it is very important the QA/Cx agent inspects the batteries for properly torqued connections prior to this or a fire may result.
UPS burn-in test.
source: Joseph Ong, UPS Testing for Reliable Backup Power _ EC&M, Feb 1 2008
Identify this test: verifying the correct UPS operation during load transfer by running the module at normal load and switching the UPS off and on until the load is onstatic bypass. You then reverse this procedure from static bypass to UPS and record _______________?
this is called combined testing and records load voltage, load current, and bypass current.
Source: UPS Testing for Reliable Backup Power | EC&MWebFeb 1, 2008
When testing a UPS you would check for what? Use the acronym WUPS I did it again!
regarding time power and discharge.
1. Walkin time.
2. UPS bypass.
3. Power transients (voltage & current).
4. Steady state discharge 50% & 100%
When discharge testing a UPS what should be done regarding recording and thermal scans with more than one person present? Note: during a test such as this there should always be more than one person present.
In this type of test, the CxA should record volts and current DC side every 15 secs. Until 2 mins then every minute. The other should do thermal scans of batteries and cables at UPS.
It is best to record what on paper for UPS testing?
Steady states and battery discharge is recorded this way during UPS testing.
What type of test is done by connecting critical loads (loadbank simulated) and testing while cutting the standby generator in and out. Repeating the same tests at 0% and 100% load conditions, and monitoring transfer between the mains supply, UPS, and standby generator to ensure that transients and waveform distortion stay within acceptable limits.
combined testing.
source: Joseph Ong, UPS Testing for Reliable Backup Power _ EC&M, Feb 1 2008
Diesel generators are susceptible to a condition known as _______ when operated at light loads for extended periods. Wet stacking occurs when carbon or unburned fuel oil accumulates on the injectors, on the exhaust valves, or in the exhaust system
B) wet stacking
Source:
It has become commonplace during data center commissioning to use _______ on the data center floor to simulate the heat load of the critical electronic systems (IT load), simultaneously testing both the electrical and mechanical systemssupporting that load. Water-cooled load banks may similarly be used to test chiller plants at their design or nameplate heat-rejection rating.
portable load banks accomplish this function.
Paul Bearn, Specifying, applying load-bank systems _ Consulting - Specifying Engineer March 2 2012
if a 3-phase load bank rated for 1,000 kW at 480 V is used on a 3-phase 240-V system, the available load would be?
(240/480)² x 1,000 kW = 250 kW
(E¹/E²)² x KW rating=KW load.
E²x P = P
Paul Bearn, Specifying, applying load-bank systems _ Consulting - Specifying Engineer March 2 2012
What is the formula for a 3 phase system for Amperes when Kilowatts are known?
power factor triangle. How do you find VA?
kW x 1,000____
E x 1.732 x PF.
for amperes when _____is known.
Holder, Ray. 2017 Master Electrician Exam Questions and Study Guide (p. 16). Kindle Edition.
What is the power factor triangle?
the difference between power and energy is what?
Power is KW and Energy is KWH.
How is PUE calculated? How does it account for the facility, IT, core, and data halls?
PUE is calculated, generally, as Total Facility Load / IT Equipment Load. In this document load is used to refer to both power and energy (kW and kWh) and all calculations will be done using both data sources. The result is two PUE numbers, one real time (kW) and one for the life of the building (kWh). This calculation is performed for each data hall, with the Core load factored in, and combined to get the building PUE.
What is to be done to calculate PUE prior to turnover?
This must be done to calculate __________ prior to turnover. The KWH/Min/Max values for all relays and meters within a building are to be reset (zeroed) out by the factory representative just prior to complete facility turnover. PUE calculation within EPMS.
Explain a core calculation?
__________Calculation: (MSG main switchgear Core Load + Generator Load)/(PDU+IRUPS)
If any downstream breaker is closed, then what must be done to the load PUE calculation?
The PQM rating must be added to the two data hall, core calculations if any breaker is in this state downstream.
Explain the IT load for mechanical? When calculating the PUE.
_________for each data hall is calculated from the total hall _________ before any core load is added in. Any communications failure or breaker posturing also does not affect the hall _________. _________ will be added up if at all possible, using every available device even if some are down.
Camlock power panels typically have what built in internally?
An internal disconnect switch.
What must the PQM's (power quality meters) be wired to?
The EPMS (electrical power management system) requires these to be wired up.
POWER QUALITY METERS (PQM) Current inputs for each channel shall be from standard instrument current transformers. And the meter burden is what? What formula is used to find the meter burden?
less than 10 milliohms for this type of device for current inputs is meter ________ and the formulas for this is.
VA=I² x Z
Z = Total CT secondary impedance
I = Secondary current
(Generally 1 or 5 amps)
This establishes the availability needs of the business applications being processed by the IT equipment.
what is a needs assessment and what it establishes.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2011 Rev.1
What is N+1” topology.
Every key system element would have a redundant piece of equipmentso that if one of the units fails, the system could still maintain its function for the IT critical load. This describes this type of topology.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2011 Rev.1
What is the number of tiers ratings in a data center available and what is the most common tier and it's downtime annually?
B) Tier 3: A Tier 3 data center has multiple paths for power and cooling and systems in place to update and maintain it without taking it offline. It has an expected uptime of 99.982% (1.6 hours of downtime annually).
What percentage of the power used in a data center is customarily DX cooling?
50%
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2011 Rev.1
What should be remembered about: The critical load is all of the IT hardware components that make up the IT business architecture: servers, routers, computers, storage devices, telecommunications equipment, etc., as well as the security systems, fire and monitoring systems that protect them.
This process begins with a list of all such devices, with their nameplate power rating, their voltage requirements, and whether they are single phase or three phase devices. The nameplate information must then be adjusted to reflect the true anticipated load.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2011 Rev.1
When calculating the critical IT load what must be remembered about the power used as per the nameplates?
Studies conducted by reputable consulting engineering firms and power supply manufacturers indicate that the nameplate rating of most IT devices is well in excess of the actual running load by a factor of at least 33%.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2011 Rev.1
Determining critical IT load: step 1:Add up the nameplate power of the anticipated loads. If the wattage is not listed on the device, it can be determined by multiplying the current (amps) by the voltage of device to get the VA, which approximates the amount of watts the device will consume. What is step 2 and 3?
step 2: Multiply the anticipated VA number by 0.67 to estimate the actual power, in watts, that the critical load will represent. (recall that nameplates are typically overated as much as 33%).
step 3:Divide the number by 1,000 to establish the kilowatt (kW) load level of the anticipated critical load.
source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2011 Rev.1
The anticipated VA number is multiplied by 0.67 to estimate the actual power, in watts, that the critical load will represent because of this?
this is done when estimating critical IT load in a data center.
the anticipated VA number is an approximation of the amount of watts the device will consume.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
What is needed to calculate VA fromKW?
The power factor is needed to calculate this two letter acronym.
Volt-amps (VA) to kilowatts (kW) conversion calculator (rapidtables.com)
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
When calculating critical IT load in a data center, the total electrical load power must include a factor for the inefficiency of this.
UPS system as well as the additional power required for battery charging is required to calculate this part of this.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
UPS efficiency varies between product models and varies dramatically depending on the loading of the UPS. UPS are rarely run at the operating points where their advertised efficiency is provided. A realistic and sufficiently accurate value for UPS efficiency in a typical installation is ___________%.
in a typical installation this is 88%.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
Battery charging is a significant but intermittent power consumer. Under normal operation with a charged battery the battery charging load is negligible. However, when a battery has been partially or completely discharged the battery charging power can be on the order of
________% of the rated UPS load. Although this load only rarely occurs, the generator and service entrance must be sized for this load.
When this has been partially or fully discharged power can be 20% of the rated _____ load. These service entrance conductors must be sized for this.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
Why is it important to know that as much as 20% of the UPS rated output (load) can result when the batteries are partially or fully discharged in a critical IT load?
although the load of the UPS is typically a maximum of 88% on average. Some CxA's test at 95% and UPS vendors hate it. Opening the front doors to facilitate cooling negates the FPT
This needs to be known because the sizing of the generator and service entrance conductors would need upsized for this need. Thus it also effects our critical IT load for a Load banking plan.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
Cooling systems vary widely in efficiency but can be broken down into chilled water systems and direct expansion systems. Chilled water systems are generally more efficient and a rule of thumb for power consumption is ___% of the total peak load being supported. Direct expansion systems require about _____% of the total peak load being supported.
_________requires 70% of the load.
_________requires 100% of the load. Regarding data center cooling systemspower consumption as a typical usage.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
Two important numbers have been determined that will assist in estimating the size of the electrical system that will power the data center environment:
two numbers plus the......
the total critical load and the total cooling load. In general, the electrical supply must be large enough to support the sum of these two numbers, plus the related data center lighting loads.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
These sources must be sized to the peak power consumption of the loads, plus any derating or oversizing margins required by code or standard engineering practice. In practice, this causes the __________ and ________ sizing to be substantially larger than might be expected...
1.414XRMS=PEAK POWER and RMS is the heating effect thus the KW load. So we multiply 1.414 x KW load for these.
The electrical service and generators regards sizing.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
Use the following formula to determine the electrical service size to supply the data center, in Amps:
Volts and E (electrons) are for the purpose of interpretation the same.
Amps = (kW x1000) / (Volts x 1.73)
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
The UPS itself may contribute to this problem if it does not operate at a high input power factor, and may cause
this may cause generator failure if it imposes a leading power factor on the generator. Leading is an inductive load.
Source: Richard Sawyer, calculating-total-power-requirements-for-data-centers, 2004 REV.0 (see REV.1 dated 2011 as well)
What is a spigot end?
B) The outlet of a pipe
The end of a pipe. Spigot end.
What is the purpose of a dialectic flange adaptor?
Used to connect networks composed of different materials or specially designed for one material. It is attached to the end or spigot end of a pipe. Consider fire pipe.
In mechanical discipline what is a PICV? What is it's purpose?
This sometimes is used in leu of a minimum flow bpass
Pressure independent control valve. It regulates pressure.
Primary injection testing, as opposed to the secondary injection test, is the only way to prove correct installation and operation of the whole protection chain, as the test involves the entire circuit: current transformer primary and secondary windings, relays, trip and alarm circuits, circuit breakers, and all wiring
A primary injection test set injects a multiple of the fault rated current of the breaker, through the breaker while measuring the trip time. The secondary injection test injects a ratio of the fault rated current of the breaker directly into the trip unit and measures how long it takes the breaker to trip.
If a transformer is shielded can the DOBLE test be done? Doble test is slang for a power factor/dissipation test that is performed on MV cables, motors and transformers. The equipment to be tested is supplied with an AC voltage below the normal rating. Simultaneously, the dielectric losses occurring to the ground are also measured and recorded
“unable to perform Doble Power Factor Test due to electrostatic shield.” As clarification, many of the Doble tests cannot be run since the transformer is shielded. However, even though the transformer is electrostatically shielded, the CH + CHL (high side to ground) test, the CL + CHL (low side to ground) test, and the excitation test can and should still be run.
The transformer impedence is sufficient for the PF (power factor) NETA test. This is also done from Low to High or High to low. Not to ground.
False
The oil effects the systems PF (power factor) as the PF is the TP true power/ AP apparent power. or KW/ VA. The KW is the resistant portion and thus would require the oil as part of the test, etc.
What is IEC61850 Goose messaging as a standard for substations?
IEC 61850-9-2 is an international substation automation standard that proposes a Process Bus communication network between process level equipment and bay level Intelligent Electronic Devices (IEDs) used for power systems protection and control
What is a CCVT?
The Capacitor Voltage Transformer (CVT or CCVT) is used to convert high voltage into low values for metering, protection, and control of HV.
On a substation HV airswitch the dielectric withstand test does not need to be done because it is a stainless rod?
False
This is not optional and is required with all other poles grounded as per NETA ATS 2021.
What is an ECM motor?
An electronically commutated motor is a three-phase, brushless DC motor. It comprises three major components: a circuit board, an electronic control module, and a three-phase motor with a permanent magnet rotor
combined heat and power an integrated system that captures the heat, otherwise unused, generated by a single
fuel source in the production of electrical power. Also known as _______?
cogeneration. (Adapted from U.S. Environmental
Protection Agency)
Source: LEED v4 Reference Guide-Interior Design and Construction.pdf
Monitoring based commissioning (MCBX) is the same as ongoing Cx?
False
Monitoring-based commissioning is the integration of three components: permanent energy monitoring systems,
real-time energy analysis, and ongoing commissioning. Ongoing Cx is a component of MBCx but should not be
confused with it.
Source: LEED v4 Reference Guide-Interior Design and Construction.pdf Monitoring Based Cx.
What is a manometer?
A manometer is an instrument used to measure and indicate pressure. There are two types of manometers, analog and digital
When setting up a data Q with KTS the voltage of the generator is 13800 and the PTs are 14400. What is the voltage for KTS software when using a data Q? Measuring from the relay SEL 751.
14400 when measuring from PTs to a relay. SeL-751.
What is the instantaneous set to for a breaker with a trip unit?
Instantaneous Region: The ________ trip setting indicates the multiple of the full load rating at which the circuit breaker will open as quickly as possible. Not a multiple of the trip setting.
The discharge reset can be used on a DX roof top unit?
False
A discharge reset on a Dx unit makes no sense as it is designed to simply run all the time.
How does the humidity get removed within a building during cooling? Specifically with an RTU.
An RTU would use a cooling and then a heating coil and it heats up and dries out the air after super cooling up front.
A scenario pops up. A UPS feeds to an LVS with main tie main. What would you want to capture during 100% burn in. the LVS is cabled across two sections.
IR scanning would be good. Also confirming as per specs burn in time.
IR scanning starts next to a loading dock. What needs checked?
The fire sprinklers needed thermal scanned. So they don't pop.
A load-bank is running and the UPS is in full bypass. What must be done to avoid battery discharge when dropping to 0% and going to inverter?
The fans need turned off on the loadbank and load dropped first. So the inductive kick does not damage the IGBTs.
When you have an MVS tied to another MVS in a main tie main configuration with an SEL 757 relay, this requires what to happen when testing downstream on fully loaded UPS's? Use the single line given below. Pay special attention to the PQM's.
The relay readings need recorded.
What is the design purpose of a main tie main configuration?
The purpose of this ______ _______ ______ configuration is to transfer load from one source to the other for planned and emergency transfers.
You can put a UPS on MBB on full load?
True
Properly automated or inter-locked with the Maintenance Bypass, the UPS can be fully load tested while still providing power to the critical load.
What is a good crest factor? This is a ratio between what?
Definition: The maximum value of a wave form. This is normally associated with electrical fault magnitude or transients.
The crest factor is the ratio between the value of the peak current or voltage (IM or UM) and its r.m.s. value. It is generally between 1.5 and 2 and can even reach 5 in critical cases.
Do you want VFDs on the same circuit as a critical load?
This can make switchgear sound like a washing machine. No you do not want it on critical load.
What is the transition time for a 1/4 cycle at 60HZ? 0.0167 seconds is one cycle in seconds.
For generator burn in what is required to be installed for the purpose of testing?
Flukes (1750s or better) need to be installed.
MMS DC (multi-module systems direct current) UPS systems require link voltage regulation to limit power flow via inverter during transients and bypass. Why?
This applies only in systems with a common DC bus and two parallel battery systems or banks.
As per a cited spec: MMS DC Link Voltage Regulation: UPS MMS system shall limit the reverse power flow via inverter during transients and Bypass <-> Double Conversion such that DC link voltage does not exceed 15V above its nominal and ensure DC link capacitors are not used above 90% of capacitor voltage rating.
With a UVR under-voltage relay can you close battery disconnects without voltage present on the batteries for a UPS? Why is one used?
No. You cannot close these on a UPS battery cabinet without voltage present. It protects the load from over voltage, under voltage and phase out conditions by sending a tripping signal to relay.
Are settings for SCCS usually given for an input breaker on a UPS?
No. These settings are not typically given for an input breaker on these.
The static switch and bypass may be hard to get to when you test a UPS. How can you trigger this for a reading using DQ analyzer software?
Usually, with this software on this equipment type, we would want to get a bypass CT on for testing under load. But you can see this with a voltage difference.
Do you want to run through the inverter for testing at load? On a UPS?
No. You want to save the batteries for discharge. This is also why the upstream ties may require the fan off and the loadbank off to prevent battery discharge.
A UPS has econo-mode. What may you want to check?
50% and 100% input and output meter, test meter (fluke), and EPMS readings are read when this mode is provided on this equipment type. Minimum.
When you pop out the SD card on a fluke it writes the data from the unit to the card. However. What would one want to remember when doing this?
The data will be overwritten if you put it back in so all data needs extracted. Using a laptop.
If you wanted to start gens for testing on load on MVSTA what must be done for setup?
MVS must be in remote and source selector in auto and gen preferred source. Gens also must be in auto.
S controller. What must you do when going to gens for load in a closed transition?
Soft load needs to be selected for the gens at the MVSG controller. Or no load for this transition.
A gen is called to run in auto. Why does it not close the gen breaker at the MVST board? Gen controllers in auto and MVST boards in remote and source selectors set to gens.
Perhaps the downstream breaker at MVST is racked out?
When loading gens to test under load for static and bypass on UPSs we are checking for what?
Checking for transition stability. For 30 minutes at 25% increments from 100 down.
When loading UPS's in the admin or elsewhere with large generators, and little load on the generators on startup what must be remembered when using a softmode?
There are utility relays that tie together and monitor for backfeed KVARs from the gens and may cause a trip out at the utility.
A UPS is started up on MBB and then transfered to Static inverter. Why might this be done?
This may be done so that you do not trip out utility.
The Economode is required for a UPS test and it may be spec required for a random sampling. There are 1000, 2000, 3000 data halls and then there is admin and MDF. How many require testing.
Typically only 2: one at MDF and one at Admin. Check the electrical Cx specs to confirm.
The purpose of the generator compatibility test is to make sure we do not have what?
sync issues.
While at 100% (250KW) load place the UPS on static bypass. Verify there are no synchronizing issues at the UPS.00129
While at 100% (250KW) load place the UPS on maintenance bypass. Verify there are no synchronizing issues at the UPS
What has to happen when taking 0% readings on a UPS with loadbank internal powered fan?
The fan has to be turned off in this scenario for the UPS.
Eco mode on an ABB UPS saves what % of the output power over the life of the equipment? At what % rate.
1% of the power output is saved over the life of this type of equipment with a 10 year life expectancy.
Determine if the below is an actual issue.
1. (GLOBAL) The Input UV Warning Limit is 90% and Input UV alarm Limit is 80% per the settings documents and in the field is in opposite configuration set Input UV Warning Limit is 80% and Input UV alarm Limit is 90%. The alarm should be 80 and the warning at 90.
2. (GLOBAL) The Output UV Warning Limit is at 90 and the Output UV alarm Limit is 80. This would alarm prior to warning.
3. (GLOBAL) sub feed under voltage is 90 warning and 80 alarm. Which appears backwards in the settings docs. See snip provided.
This is not an issue as the warnings come in above the alarm because these are all "UNDER".
A PDU requires testing and the meters are connected to the load side of the PDU. Does this suffice testing?
NO. Because the output breakers need verification of the calibrated amperage and voltage for EPMS and potentially a PQM or local meter if one is provided.
What is the following a photo of? Consider the connection and what it is called.
MV pfister connections. Under an E-house.
When a script asks for:
Apply 25% (125KW)load for a minimum of 30 minutes. place the UPS on static bypass. Verify there are no synchronizing issues at the UPS.
While at 25% (125KW)load place the UPS on maintenance bypass. Verify there are no synchronizing issues at the UPS.
Does the UPS go into static bypass or just direct to MBB? What happens to sync when in MBB?
The MBB means the UPS is no longer in sync. Also the UPS goes through static when MBB is selected on the HMI (Schneider UPS's) and is typical of UPSs.
A PDU may have a requirement for what on loss of load that needs checked to specs and tested at FPT?
A PDU may have a shunt trip during this event that needs checked during FPT.
The following spec is highlighted. How does this get accomplished? IE: single phasing a 3 phase load bank.
Conduct testing utilizing single-phase (phase-neutral) loading via downstream RPP/CTP to confirm metering of the neutral conductors and reporting to breaker trip units. The load shall be connected at the farthest possible connection point from the PDU subfeed breakers and shall be of magnitude no less than 40% of the neutral feeder ampacity. Repeat for one phase-neutral connection on all PDU subfeeds on all PDU modules. For circuit breaker trip units with ground fault trip, temporarily lower ground fault threshold to below load level applied to confirm operability of the ground fault sensing. Return breaker setpoint to prescribed setpoint in accordance with the Electrical Power Systems Study.
This is accomplished by landing A to A and neutral to B at a 480V load bank with separate power provided and the fans must be powered separately. These are connected at the tap box for the loadbank at busway end.
The following is allowed if the CDE (certificate of compliance) in the submittal asks for the splice to be sufficient for bonding as supplied by the manufacturer?
The bonding conductor needs secured to the tray metallically for bonding and a jumper across each joint. A spec review and submittal CDE found this is required.
The emergency lighting dims on emergency mode with a lighting inverter. Is this correct?
No. Lights can dim with an inverter but not in emergency mode.
Two bathrooms in the loading dock are missing emergency lights. They have one toilet in each. The two restrooms at the main office have emergency lighting and several stalls. Should the smaller rooms have emergency lights?
No. Because the path of egress from a public space (multiple users) is the standard.
An STS out of phase transfer is typically how much time?
13ms. This is why the soec required 10ms is not realistic.
What is the following device a picture of?
PM5563 (5500 series): This device is a DIN-mount energy meter with an additional 96mm by 96mm backlit LCD remote display. The meter provides Class 0.2S accuracy per IEC 62053-22 standard and 128 samples per cycle. The meter will measure Energy, Active and Reactive Power, Voltage, Current, Frequency, Power Factor and up to the 63rd Harmonic
Overcurrent Trip Switches (OTS’s) on the breakers prevent breaker reclosure onto a fault or overcurrent. Place the Auto/Manual switch in the "MAN" position before resetting the OTS. When the PLC detects an overcurrent trip signal in the "AUTO" mode, the PLC will?
Regarding overcurrent trip switches this will lockout all
breakers capable of being closed to the respective faulted bus. The PLC will also prevent all breakers capable of being closed to the respective faulted bus from closing until the fault condition is reset.
The voltage sensing on a 13800 volt MV board is done how?
Voltage sensing is performed on the primary (incoming cable) line and one phase of the distribution bus. Potential transformers (PTs) rated at 14400 volts to 120 volts are used for all voltage measurements.
Voltage sensing on the primary of a 13800 volt medium voltage board is accomplished via the output of what?
It is very important to use three individual single phase PT transformers rather than one for 3. For reliability.
The output of three potential transformersare wired through fuses to the SEL relay analog input card. Logic in this relay uses that voltage and closes an output contact, which provides status to the ABB controls, signifying that 13.8 kV is present on the incoming cables.
Once the PT (power transformer) senses voltage on the primary of a 13800 volt switchgear via the output of 3 PT's through fuses to the SEL relay analog input card, the relay senses this voltage and closed an output contact, which provides a status to the ABB controls, signifying that 13.8KV is present on the incoming cables. What happens regarding a breaker and compression of voltage?
The voltage is also transmitted, via 61850 MMS, to the EPMS system for monitoring the 7967 VAC line to neutral voltage. Additionally, the primary and distribution voltages are compared for a breaker close permissive sync check circuit.
What is required in open transition mode on a transfer switch?
Single operator with programmable time delay on transfer between live sources in open-transition mode.
A static transfer switch is designed to transfer critical loads between two independent AC sources without interruptoin or with a transfer time of less than?
____________________, is an automatic static switching equipment designed to transfer critical loads between two independent AC power sources without interruption or with a transfer time of less than a cycle (20ms)
Open/Close pushbuttons on the circuit breaker should not be used while in what?
These pushbuttons on this should not be used in “AUTO” mode. Using the Open or Close pushbuttons on any of the _______in the PLC control system will result in an AUTO-FAIL condition.
What must one remember about OTI (open transfer inhibit) generated by LV switchgear and executing OTI regarding critical load?
The OTI signal generated by the LV switchgear shall inhibit open transfer operation of the transfer switchgear assemblies. Executing Open Transition with the OTI signal active will
cause loss of critical load.
An open transfer inhibit is set (OTI) for a UPS that feeds a main-tie-main switchgear configuration to STSs (static transfer switches). What happens when the downstream UPS is in bypass mode?
The signal will be active when a downstream UPS is in bypass mode or the LV switchgear maintenance bypass breaker is closed, or any downstream STS is switched to position connecting the load to a non-conditioned/non-UPS backed up source.
If communications is lost with the switchgear, 480V, what typically happens regarding open transition inhibit?
If communication is lost with the LV switchgear, the system shall activate an internal OTI signal and follow the same requirements as the external OTI signal is active.
What is SNTP? What happens after reboot?
The purpose of the Simple Network Time Protocol (SNTP) is to synchronize the clocks of various devices. Since the switch does not retain the time/date after reboot, the SNTP server can be used to re-sync the system clock
The following illustration shows target reset. What does this do?
TARGET RESET – All ‘latched-in’ LEDs can be reset (turned off) by pressing the Target Reset pushbutton, this is usually done as the last step in the procedure that first determines the reason for the TRIP and completes the repairs of it.
What does the lock function accomplish on the following relay? What does the lock function do? How long is the LED illuminated?
Front Panel Pushbutton Lock On or Off - Continually press the LOCK operator control pushbutton for three (3) seconds to engage/dis-engage the lock function. While this pushbutton is pressed, the corresponding LED flashes on and off, indicating a pending engagement or disengagement of the lock function. The LED illuminates constantly to indicate the engaged state. While the lock function is engaged, the close and open pushbuttons on the A relays are disabled.
What is Utility Reverse Power Trip Logic? How does it work?
In MV parallel sources. The output is wired to the 86U lockout relay to provide protection for when the utility is in parallel with another source. This protection is enabled in both relays if two are provided and typically they are. Reverse power protection is enabled whenever the main is closed to prevent backfeeding the source and to provide some anti-islanding protection.
What does outputs are latched mean? Why is this important to check in EPMS checks?
Regarding a jumper: The jumper was a standard thing LayerZero does for the spare breakers so the system does not throw alarms for the spare breakers being Open, the default for the PDUs is to alarm any Open breakers since an open breaker could mean a loss of load.
An output latching instruction is an output instruction used to maintain or latch an output on, even if the input condition changes. This is important to check in EPMS configurations because this may be "latched" and thus not clear the alarms. This is sometimes done on spare breakers with reversed wiring with a jumper to ensure the spares are shown as green at all times as they are not used. Which is not correct as this does not account for expansion and thus should be commissioned for that.
What is an SER and how would this regard SNTP?
The Sequential Events Recorder (SER) captures the change in state of any configured RWB. The report includes time and date stamped events for all used elements. Thus SNTP (serial network time protocol) would be required at all SERs.
What is the relay settings file extension for an SEL relay?
RDB is the file extension name for this. However upon download it will be a compressed event report from an _____ relay is downloaded and saved with a . cev file extension.
Explain how the outputs on the CT's for SEL relays is wired. Consider testing.
The outputs of these CTs are wired through shorting-type terminal blocks, then test switches (utilized for relay testing) and then directly into the protective relay.
When taking measurements for KTS DQ Analyzers for the medium voltage generators at the loadbank breaker in the MV gear, the voltage is 13800. The KTS is thus set up for 13800 volts.
False
Voltage sensing is performed on the primary (incoming cable) line and one phase of the distribution bus. Potential transformers (PTs) rated at 14400 volts to 120 volts are used for all voltage measurements. Thus this would need to be set at 14400volts for testing.
What is safe mode? What inhibits it?
50P2: Definite-time protection This relay is created by applying intentional time delay after crossing pick up value of the current. A definite time overcurrent relay can be adjusted to issue a trip output at definite amount of time after it picks up. Thus, is has a time setting and pick up adjustment.
This is also known as safe mode and is activated by 67P1T (ANSI code) is the main instantaneous overcurrent element and is inhibited with harmonic blocking and not being in maintenance mode. 50P2 is the maintenance mode (safe mode) instantaneous setting which requires the mode (IN201) to be active.
Explain how an automatic transfer controller works in hot standby with a PLC for a main tie main system? What is required for hot standby redundancy switching?
ATC - Redundant Hot Standby PLCs – Automatic Transfer Controller, this device monitors both Source 1 and Source 2 and carries out the required sequences, automatic or manual for the Main-Tie-Tie-Main System. This component has the following features:
• Fiber Optic Link to be field installed for hot standby redundancy switching
• Modbus TCP/IP interface for customer monitoring and control via touchscreen provided by others
• Monitors redundant remote I/O over ethernet
Two 480V boards and the gen breakers all have a latched command function. What must be done to reset this latched command regarding the PLC?
If a breaker fails to close when commanded to close by the PLC, the respective breaker will be in a “Fail To Close” state. Any “Fail To Close” state will remain latched ON until the Auto/Man switch is placed in the “MAN” position to reset
the condition.
Below is a photo of an ATS. Why would the center off not function correctly? Which setting would need to be correctly set and is it?
Source loss center off delay is disabled and this would not work in that scenario?
Closed transition between two utilities what is done with communications to the substation PDCS controllers and why?
Prior to executing closed transition between utilities, the AZ/NDS system shall communicate with the substation PDCS controllers, to freeze/adjust substation transformer tap changers to minimize recirculating currents and potential trip conditions.
Regarding sync, what must be active when paralleling utilities?
Close transition can only be allowed when the sync-check permissive is active.
When CLOSED TRANSITION is selected, any Automatic or Manual transfers shall be executed by paralleling of two sources
True
The closed transition will happen in any mode.
Soft Loading/Offloadingbetween utility and generators. Exporting power to the utility is not allowed. Protective relays on the Owners and Utility side will trip on export detection c. Paralleling of sources during soft loading/unloading shall not exceed a predetermined time that will be site specific and field settable. What accomplishes this from a controls perspective?
The PDCS (power distribution control system) does this regarding soft loading.
Executing Open Transition with the OTI signal active will
cause?
When executing open transition with this signal active it will cause a loss of utility.
When communication with the switchgear is lost or when a downstream UPS is in bypass modeor the LV switchgear maintenance bypass breaker is closed, or any downstream STS is switched to position connecting the load to a non-conditioned/non-UPS backed up source (UPSs in bypass)... this becomes active. What is it?
open transition inhibit does this with these bypass modes etc.
What happens if the OTI (open transition inhibit) sees a loss of comms in the LV switchgear? Internal or external?
If communication is lost with the LV switchgear, the system shall activate an internal OTI signal and follow the same requirements as the external OTI signal is active.
This shall allow make-before-break manual or automatic transfers. On a UPS.
The inverter shall track the bypass frequency continuously, providing the bypass source maintains a qualified frequency. The inverter shall change its frequency (slew rate) at less
than 1Hz per second (adjustable as specified) to maintain synchronous operation with the bypass.
Source: 26 33 53 - 2 - UPS - WKE.5X -CORGANci.pdf 2.05 inverter part D.
In which mode is the inverter off? ECO mode or ECOnversion? Regarding a UPS.
The fundamental difference between ECO Mode and ECOnversion Mode is that the inverter is off in ECO Mode whereas it is on in ECOnversion Mode. This means that the load is exposed directly to the unconditioned utility power in ECO Mode, this is not the case in ECOnversion Mode.
Source: SE.com
The term DC-DC converter denotes what portion of the UPS module and does what?
The term _____________, as used herein, denotes that portion of the UPS module containing equipment and controls to regulate the output of the DC link and Battery Voltage to ensure long Battery life and support full load at safest battery cut off voltage.
This permissive shall be referred to as the CTPC - Closed Transition Permissive Control
What North American spec division concerns Medium Voltage?
Division 33
Cable current limiters are sized to a current rating?
False
Unlike fuses, cable limiters are selected by cable size rather than amp rating, e.g., a “4/0” limiter will carry the current of a 4/0 cable.
Source: Technical Data 1042 Effective February 2019 Supersedes October 2017 250V and 600V current limiters.
What is the function of cable current limiters?
Q. Bus taps for control power and voltage monitoring shall be accomplished using bus mounted Cable Limiters, fuse type, and double-insulated wiring, minimum #10 AWG/5.26 mm^2.
Under high short-circuit conditions, limiters cut off
fault currents within one-half cycle (0.008 second)
Potential transformers and coupling capacitor voltage transformers (CCVT's) have been used successfully for providing voltage to the inputs of meters and relays since the 1960's. At voltage levels above 138kV economics dictate that CCVT's be used to provide secondary voltages to relays.
How does a best battery selector work?
A properly engineered Best Battery Selector (“BBS”) consists of two large diodes, specialized heat sinks, and voltage surge protection assembled and mounted in a metal enclosure. During normal operation with two good sets of batteries, the diodes are “on”.
What is ZSI?
ZSI (zone selective interlocking) is an interlocking system used to enhance the selective coordination level of electrical distribution systems.
What is a corrosion coupon rack and its purpose?
A _________________ is a simple corrosion monitoring device that uses corrosion coupons, which are strips of metal that match the metals in the system where they are installed. system water is allowed to pass over the metals for between 90-100 days. After the test period expires, they are pulled out, sent to a lab, and weighed. The difference in weight will represent the level of corrosion in the system.
What is ZSI
Zone sequence interlocking. This is customary on a P and S board primary and secondary. This allows a specific sequence for the tie breakers.
LSIG is a breaker. And they did not use the I. Why?
The SCCS instantaneous would be the phase to phase trip. The study would have determined this is not required.
A fluke 1750 can measure for DC current?
No, because the hollow flex CT is required.
When load banking the kits are hooked up for fluke and KTS and the busway tap boxes are open as well as PDU breakers and back of PDUs. What is required for safety?
Firewatch.
When capturing LVS PQM data for the status tables under FPT the UPS 100% on inverter can be captured?
False
The UPS must be in module and not system (all together) to capture this and on inverter.
In the below screenshot is there a problem?
In this case the KW is backwards and the trip unit needs adjusted. yes.
Diagnose the below screenshot.
The amperage is far too high on neutral.
The below has arrows that are hollow and some that are filled in. What is the difference?
With load this would show up as a difference in the phasor relationships between voltage and current.
What is the current status of this system UPS?
Currently on inverter.
A given EPMS system uses a color code as follows:
Breaker Status – The color of each monitored breaker shall be as follows:
a. Open - Green
b. Closed - Red
c. Tripped - Orange
d. Withdrawn/Test position - Yellow
e. Not monitored - Purple
However, the EPMS graphics states the following required by spec.
1. Green – Normal Operation
2. Amber - Non-normal Condition – Warning only
3. Red – Critical Alarm – Immediate action required
4. Magenta – Maintenance Mode
Why would green be normal operation but open on the EPMS regardless of normal position?
The floor view would show the EPMS graphics requirements and the single line would show the breaker status requirements. Different colors for the same status.
The % load for the UPS is at 53% but at a 75% load status. The UPS is running in system mode with all 4 UPS's together. Why is the load % different?
The load % would be different for this test as the UPS is tied to all others and is using the load of the hot aisles and thus lowers the load at the UPS since they are sharing the load.
The below image of DC is from KTS software on a DQ power quality analyzer and is normal?
This image is normal as this is noise pickup prior to the test.
The below image is of a PDU. What must be done when closing the tie breaker?
The sync check should come on and if not then either A or B must remain open. On this item of equipment.
Example script FPT:
STS-PDU shall accommodate interfacing to external AC or DC power source to ensure?
This ensure seamless monitoring of STS-PDU via EPMS/ENMS without source 1 or source 2 available.
A phase out of sync EPMS alarm is received at the EPMS graphics HMI. The UPS is discharging on battery. This is an issue that needs recorded?
False
The UPS source is on battery and the phase source is in phase. Thus the battery as it discharges means the STS (static transfer switch) will be out of sync from UPS to utility. Primary (P) and Secondary (S).
When testing a PDU and STS how are the meters usually set up? Regarding excitation.
For this item the S1 input and the S2 input require a separate CT (x1) for the excitation of the transformers from one phase on each input to trigger the recording on the voltage outputs on the KTS software (DQ analyzer) for the 10miliseconds excitation transient confirmation. This makes sure the STS does not loose excitation.
What is MODBUS RTU?
The IP address identifies a specific device in the network, while the function code and data address identifies a specific data point within that device
Also known as Modbus TCP/IP. Modbus RTU messages are a simple 16-bit structure with a Cyclic-Redundant Checksum. The simplicity of these messages ensures reliability. Due to this simplicity, the basic 16-bit Modbus RTU register structure can be used to pack in floating point, tables, ASCII text, queues, and other unrelated data
unloaded transfer the LVS is done how? With a P, W and S board and tie breaker to W (UPS board)?
________ is done on the LVS01P and close the tie and open the MV breaker that feeds the 01P and transfers to the LVS02S board.
What is RVT?
room validation test. Usually a mechanical test.
How do you do Out of Phase Transfers due to Source Loss at 30, 90 and 180 degrees out of phase between Source 1 and Source 2. Determine worst case condition for use in Electrical Room Validation tests. For STS's?
You run one source on generator to conduct this test on STS's called a block load transfer. This will get the 120 degrees out of phase which is a variance allowed by some clients versus 30, 90, 180.
In one case a PUE was captured at a data center from the PQM's on the LVS boards using total facility power/IT equipment energy = PUE. Is this correct?
This use of determining PUE is done in some data centers but does not take into account the relays which would capture transformer losses and cabling impedance losses, etc. This method uses other than the relay's and is typically not correct but is based on client preference.
What's the difference between single-conversion and double conversion?
Unlike the double-conversion system, the incoming line to the single-conversion UPS is not rectified to produce dc power to provide input to the inverter.
___________ or approved equal disturbance analyzers capable of sub-cycle recording with a wave form analyzer to record transients. Sub-cycle recording shall be provided for voltage, and current.
Fluke 1750 is capable of this as is the later Flukes like the 1770s.
How does a power analyzer work?
It works by strategically sampling the AC voltage at various points along a waveform shape. From there, it digitizes all points or values and utilizes a microprocessor in order to execute a numerical analysis (which arrives at harmonic frequency magnitudes).
Where would you connect the flukes in the following scenario?
The MIB is the one that lacks any PQM etc. so this would be a potential miss.
The flukes would be connected at the MIB, TB, input, and output for UPS.s
What is the required to run the generators for out of sync transfer on STS's? Regarding source selectors?
The source selector must be in gen mode when the MVST boards are in auto selected and remote at the MVSG and generator controllers as well.
What is optimization status on an MVST board?
This allows the generators to all come up and online and then shed all but two gens (N+1) to allow only enough needed to not trip out utility on reverse KVAR (known as soft load). The 60 seconds counts down and then the gens start to shut down with the most hours ran shutting down first. In priority.
How does an out of sync transfer for 30, 60, 90, 120 occur on an STS?
The running of the generators for utility source would cycle through out of phase sync, and the STS would allow a transfer to the B bus [gens] outside the 15 degrees either side of the phase and at 120 [spec]. In the above photo, the black arrow shows a 53-degree out of phase shift due to gens. This is done by opening the preferred source breaker.
What is also known as flying start? Regarding soft load and gens.
Starting into a rotating load. The soft load on the MVS would have reverse KVAR when off loading the gens back to utility.
Source: 26 29 23 - Variable-Frequency Motor Controllers.pdf part 2.09 CONTROL FUNCTIONS AND ADJUSTMENTS (garin)
What may be the cause of the following issue?
3301.XFMR01P SEL-751:
Phase B current is reading 2700A while Phase A is at 4673A and Phase C is at 4671A. Additionally, Ground current is reading 1965A.
The shorting pins were left in the CT's is a good reason for this current imbalance
UPS systems that have the same frequency and voltage input and output are usually supplied with a bypass circuit. This circuit consists of a static transfer switch or an electromechanical transfer switch, or both. The purpose of the bypass circuit is threefold:
First, to connect the bypass source to the load in case of failure of the UPS; second, to enable bypass of the UPS
for maintenance; third, to assist the UPS output in supplying fault current if a fault occurs.
Source: IEEE Orange Book 1995.pdf pg. 181 of 319
Static transfer switches commonly have a short-circuit rating at least _________% of the continuous rating for 1–5 cycles. This is more than adequate for the fault-current avail-ability of an inverter, but careful overcurrent device setting will be required when the fault current is from a larger alternate source.
These will typically have a short circuit rating of atleast 1000% of the continuous rating for 1-5 seconds continuous.
IEEE Orange Book 1995.pdf pg. 221 of 319
As previously stated, the basic components of a UPS system are the battery, a rectifier or bat-tery charger, inverter, and often a ______________.
static transfer switch is one part of the basic components of the UPS system. There are 3 others.
Source: IEEE Orange Book 1995.pdf pg. 222 of 319
Isolating transformers provide some measure of surge protection because of the physical isolation
effect on circuits. But because of their magnetic coupling and distributed capacitance between windings, they are not perfect isolators and often additional surge protection is
required. So-called ___________offer the best protection in that they provide line isolation, surge protection, high-speed voltage regulation, and, in some cases, a degree of wave-shape filtering for protection against harmonic distortion, all in an integrated package.
Line conditioners.
Source: IEEE Orange Book 1995.pdf pg.223 of 319
What type of switch describes the following: "shall be a solid-state, three-pole, dual-position transfer switch designed to switch automatically and manually between two three-phase AC power sources without an interruption of power to the load."
This describes a static transfer switch by definition. "solid state.... number of poles and positions etc."
Source: 300b7dce-ec94-4cc2-b36a-e5e5c878189c_production_merged.pdf pg. 1 of 16.
If you wanted to conduct a room validation for IST what would you want to ensure was done prior to testing?
All L4 scripts need to be completed.
All Issues recorded in L1-L4 need to be re-verified and closed.
Load banks configured based on RV/IST Load Bank Plan
All electrical equipment is being fed from normal sources.
All containment in place and ready to go.
Hot aisle containment doors are fully closed.
The proper containment sections are open to allow cold air into the hot aisles.
All ceiling tiles in place and ready to go.
All openings that would normally be closed for a finished product need to be sealed (for example, any openings where racks go through a wall and fire block should be in place but may not be quite yet).
All doors are closed and marked with signs for no entry.
Any areas requiring red danger tape to be in place.
All unnecessary materials removed from all spaces.
All controls are in automatic operation with any and all overrides removed.
No current active alarms on system.
All BMS/EPMS trending/screenshots are set up per direction in the Room Validation scripts.
There is too little load on the UPS in burn in as it is tied to a downstream PDU. There are 4 PDU's on 4 UPS burn ins. The UPS is 1MW and the downstream W board can handle 2MW. What might be wrong?
The load is likely not evenly distributed on the PDU and thus a check of PDU on S1 is needed as S2 means not on UPS.
If you are brining up load on say PDU's downstream of the UPS what must you do regarding load as you bring it up to 100% for burn-ins?
You must make sure that the PDU load for ________ is brought up so that the boards are matching for load at the PQM and also at increments. So that you can reach just below 100% without accidentally putting too much load on any one PDU.
Can you put an STS in S2 while under load at the upstream UPS?
No. You cannot do this regarding an STS with the UPS upstream providing load.
4 UPS's are connected in a multi-mode system and one UPS needs to be ran on steady states and transients. How do you ensure you have only one UPS on load?
The vendor would ensure the load is just below 50% and put the unit we do not want loaded in static bypass.
A solid core CT would use what to keep from burning up.
typically a resistor is provided.
The mirrored bit is what?
they are called mirrored bits instead of bits reversal because the signal is both directions. These are common with SEL relays.
Mirrored Bits communications is an innovative, low-cost, relay-to-relay communications technology that exchanges the status of eight internal logic points called Mirrored Bits, encoded in a digital message, from one device to another.
What can be done to prevent preheat air conditioning coils from freezing?
Increasing the fan speed will prevent this from freezing in air conditioners/ AHU's.
Explain what a freeze stat is in an AHU and what it does. What are they also called? They are located where and set to what? When this senses cold it sends a signal to do what?
Freeze stats, or low limit safety switches, are positioned between the preheat and chilled water coil and monitor the inlet air temperature. They are typically set at 37F (adj). When the freeze stat senses cold, it sends a signal to shut down the unit and start the circulating pump for added protection.
Regarding ΔT for chillers: As for the location, they should be placed on the strategic points on the rack. They can be placed on the top, bottom, back, and center. The ASHRAE recommends using________or more sensors for the most accurate reading.
6 or more sensors are recommended for this.
Source: https://www.akcp.com/blog/understanding-the-4-delta-t-of-a-data-center/ and ASHREA. Data Center Encyclopedia.
The fans are running on chillers with harmonic filters and the mechanical contractor records an issue for this because the harmonic filters are on standby. Why?
If the fans are constant speed, independent of harmonic mitigation they will be ON as long as they have power and completely decoupled from Chiller load (aka magnitude of harmonics). This issue will be closed.
Source: CONSTRUCTION ISSUE FO-165-3 Morgan
Author
johnbowens
ID
358152
Card Set
CX Process & Lessons Learned (infrastructure risk) Data Centers
Description
A rundown of the aspects regarding the commissioning process for both mechanical and electrical that will allow a person to avoid pitfalls and lessons learned from commissioning complicated systems globally.