Traits of an Operator
- Self motivated
- Area 1 : Metro
- Area 2 : South L.A.
- Area 3 : West L.A.
- Area 4 : East Valley
- Area 5 : West Valley
Number or Operators and Stations
Currently 100 operators
Currently 150 Stations
One of the Responsibilities of the OTC
Train Personnel to become Operators
The process by which you will become thoroughly familiar with every station in your assigned area.
These areas of performance are scored subjectively
- Abilities and Traits
Operators are responsible for creating and maintaining
a safe working environment for personnel working on circuits and equipment in Electric stations.
Unit of Electrical potential and its Symbol
the Volt: E
Device for measuring Difference in potential
Direction of Electron flow
From Negative toward Positive
This is called Current
Metric prefixes: Kilo
- Abbreviation : K
- ie: 1kv = 1000 volts
Metric prefixes: Milli
- Abbreviation: M
- ie: 1mv = .001 volts
Metric prefixes: Mega
- Abbreviation: M
- ie: 1MV = 1,000,000 volts
Symbol for Amps / Current
Symbol for Resistance or ohms
R or Ω
Solve for Resistance in a Series Ciruit
Rt= R1 + R2+R3+R4.......
Solve for Resistance across a Parallel circuit
- RT= 1 + 1 + 1
- __ __ __
- R1 R2 R3
Combo Circuit calculation order
Always solve for Parallel first
is the resistance equivalent of like resistors
- Ie: 2 10Ω resistors in parallel where number of like resistors is represented by n Req =R/n or
- Req = 10Ω / 2
The 6 transmission Voltages DWP uses
Generation Tie Lines
Connect Generating Stations to Receiving or Switching Stations
- Form an irregular ring to transmission lines around the city connecting Receiving and Switching stations together.
- The belt provides redundancy and greater system reliability by connecting stations to more than one source
Trasmission lines connecting a Switching or Receiving station to only once Receiving station directly. Theses types of Receiving stations are said to be Radially supplied.
Inter-Utillity Tie lines
- Tie to other Utilities
- These include:
- Burbank Water and Power
- Gelndale Water and Power
- So cal Ed
- Arizona Public Service and the Bonneville Power Admin
- Abbreviated: SS
- allow multiple Transmission lines to connect together
- may also serve as inter-Utility tie
- Abbreviated: RS
- Connected Via Belt or Radial lines
- Tansmission Voltage buses (operating at only 138kv or 230 kv)
- connect Transmission lines and also have Transformers (Power Banks) that connect transmission system to the Sub-transmission system
- Abbreviated: DS
- Serve as connection between the Sub-transmission system and the Distribution System.
- Contain Power Banks that step down voltage to 4.8kv and contain voltage regulators
Principal advantages and disadvantage of hydro electric plant.
- Was relatively inexpensive to build, but not anymore
-Site location may require producing electricity some distance from where it is consumed.
The Owens River Gorge
- Three facilities (control, Middle, and upper Gorge)
- along the Owens River with acombined capacity of over 100MW located 260 miles N of L.A. near Bishop
The Owens Valley
Five Facilities at Pleasant Valley, Big Pine, Division Creek, Cottonwood, and Haiwee with a combined generating capacity of over 7.5 MW
Los Angeles Aqueduct
- Six Facilities with a combined generation capacity of 75MW
- PP 1 , and PP 2 located in Sanfrancisquito canyon
- were the first 2 PP built specifically to power L.A.
- Features Pump storage tech.
- Capacity 1200MW
Department does not own but receives 15% of the power it generates
Thermal Generating Plants
- -Harbor Generating Station in Wilmington
- -Valley Generating Station in Sun Valley
- -Scattergood Generating station in Playa Del Ray
- -Haynes in Long Beach
- -Apex in LAs Vegas
- - Palo Verde a nuke plant in Arizona
- -intermountain in Utah a coal plant
Line VS Cable
A Line is circuit that has at least some portion ABOVE ground. Solid line
A cable is 100% underground. Broken line.
A circuit that leaves a station to supply only 34.5kv Customers directly they dont connect stations.
how many Phases in our system
- 3 phase 120° apart
- 360° total
- 60 Hertz in one second
- 2 alterations per cycle
When both Voltage and current start and stop at the same time they are....
When the current wave starts before or after the Voltage wave they are ...
Out of phase
Term Lead vs. Lag
- Used to describe the phase relationship
- Lead : the current wave is leading, or ahead of the voltage wave.
- Lag: the Current wave is behind the Voltage wave.
AC circuits are affected by non pure resistance sources the total opposition to AC current flow is called impedance.
Voltage and current to be out of phase.
ELI = Inductance- Voltage leads Current
ICE = Capacitance - Current leads Voltage
AC 1.4 times current to
Produce Same DC power
3 Phase generation Advantages
- More effective operation
- Need 25% less conductor material
- Superior cost and operating characteristics
Transmission operates above
Cost of underground vs overhead
- 9 x more expensive than overhead at 115kv
- 16 x more expensive than overhead at 34.5kv
most expensive part about overhead
Most expensive part of underground
Generation symbol and intials
Power plant Symbol and abbreviation
34.5kv connects RS to DS and DS to DS
Supplies large customers Directly at 34.5kv IS
Point at which Feeders splits into multiple branches called primaries.
Below 69kv above 4.8 Kv usually 34.5kv
Station Equipment names
- Transformers aka Powerbanks
- Circuit Breakers : CB
- Disconnects : DC
- Insulators and Bushings
Diff between Insulators and bushings
Bushings are hollow and allow a conductor to pass thru them
Insulators are solid and insult a connection point
Circuit Breakers are designed to perform what functions?
- -Open / close electrical circuits
- -Energize circuits
- -De-energize circuits
- -interrupt normal and abnormal values of current flow in electrical circuits
This type of switching, performed by the operation of relays, normally creates intentional power outages.
Performed by Operators. This type of switching is usually in response to power outages and abnormal conditions such as overloads.
What is Routine or Planned switching
In this case the current that normally flows in this equipment is routed, by switching to an "alternate source" before the equipment needing repairs is de-energized.
Electrical Function of switches
- The manipulation of relatively high values of current and voltage under load or possibly loaded conditions, and
- The switching of circuits top provide a visual confirmation of de-energized and/or for circuit selection under unloaded conditions.
Purpose of Disconnects
-To provide a method of visually confirming that a circuit has been Disconnected
- To energized or de-energize short sections of conductor
- -Insulating oils
- -Pressurized inert gasses,such as air, but not oxygen
- -Sulfur Hexaflouride gas SF6
- -Vacuum Chambers
2 Elements that can destroy the interrupting capabilities of dielectic medium
Dirt and moisture
Pressurized hydraulic, pneumatic and compressd spring systems are examples of
Operating Mechanisms and Operating Forces
The Operating time, from fully open to fully closed, in many large CB's is often less than.
Auxiliary devices that direct the operation of the CB
The current that continues to flow across the opening of contacts of a circuit
When air becomes Ionized it
no longer functions as an insulator but becomes a conductor.
Disconnects must never
be used to interrupt load current.
What is a CS
Customer station at 4.8kv
34.5kv customer station
What are Buses
Buses are conductors that serve as a common meeting point for two or more circuits in a station.
When current flow in a coil causes an emf to be induced in itself it is know as .....
The characteristic property of a circuit that accounts for the production of an induced voltage or counter emf is called.....
Well designed transformers are what % efficient
The measure of the relative ability of a substance to conduct magnetic lines of force
The losses due to the resistance of the windings are called
copper losses or I² R losses
Small and medium sized transformers are
Transformer oil in good condition must be able to withstand
30kv applied across two flat electrodes submerged in a sample without arching.
Electrodes used are 1 inch diameter and spaced .10 inch apart
The ratio for the primary to the secondary voltage equals....
the ratio of the number of turns in the two windings.
Solve for current or voltage
The entire formula for ratio , current , voltage is
- EP = Is = Np
- ___ __ ___
- ES Ip Ns
_______ are used to step voltage down to a safe value usually 120v and provide a source of voltage for metering, lights, and protective relays.
________ are use to step down current to a safe value, a max of 5 amps they provide a secondary current for ammeters and for circuit protection.
The basic principle of good nomenclature is
a complete name must include the minimum information needed to clearly differentiate the circuit or equipment from all others.
how many switching stations in the city
- 4 and all names derived from the street name nearest the control room.
- Olive River
- and Sylmar
Station names are included when...
a circuit or piece of equip belongs to more than one facility.
All equipment is designed to operate at or near an optimum electric potential. This is called....
The Proper name of a CB
includes the name of the circuit and the piece of equipment that it connects together.
The normal source name comes________ the normal load name on a circuit.
- Haynes Velasco line 1
- Velasco-factory Cable A
Equipment names can refer to.
The name of the Bank that supplies it.
When naming a circuit or piece of equipment the circuit name (or Bank name) comes_____ with respect to the Bus.
Bank 1, 4.8kv Front bus, CB
Feeder 5-5, 4.8kv Transfer Bus, Disconnects.
The operating time, from fully open to closed in many large CBs is often less than__________
CBs are usually operated by the use of stored mechanical energy that acts to move the contacts these forces may include.
- Pressurized Hydraulic systems
- Pressurized Pneumatic Systems
- Compressed springs
Mechanical indicator for a CB is called
Semaphore and is located at the CB
5. Steps taken to ensure that current flow has been interrupted in a circuit before opening a disconnect. are
1 Open or check open the CB
- 2. Check ammeters
- 3. Check CB indicating lights should be green
- 4. Check Semaphore
- 5. Crack open the Disconnect.
a disconnect is an electrical device with
normally visible contacts
- I = currentE = Voltage
- N = Turns
- R = resistance
A Red Flag and a Green light mean.
A Green flag and a Red light means
Not in agreement
In Agreement means...
Flag and light are same color
When on local control ________ must be on closed bank CBs
If a second coil is placed in the field of the first coil that is connected to an AC source, the rising and collapsing magnetic field of the first coil will cut across the second coil and will induce an AC voltage in the second coil as well. This is know as
The Basic principle of correct nomenclature is:
A complete name must include the minimum information seeded to clearly differentiate the circuit or equipment.
DS-48 Tujunga is an ____________
Outdoor, department style station with a double bus-single breaker high side.
Indoor, underground style station with a double bus-single breaker high side and an older style sectionalized main bus with rack out breakers on the low side.
What is a source
A circuit that is a "normal" supplier of energy-the circuit from which current flows.
What is a Load
Load is generally considered the circuit that is connected to a source - the circuit to which current flows.
For operating purposes, the terms "connected" and "disconnected" refer to....
the use of disconnects and CB'c only.
Connecting two circuits together so that current can simultaneously flow through both of them is known as.....
The act of un-paralleling circuits is known as.....
Breaking parallel or separating
Providing an alternate source means....
Paralleling a second bank with the one that is being taken off.
Dry Run and Power Flow Check are...
Required elements of bank switching procedures
Switching plans are required and must include....
the name of the circuit being operated and the major steps required to perform the switching.
What is a disadvantage of a steam plant.
High operating cost
what does nominal
What degrees is peak amplitude in a sine wave
90 and 270
what is a high voltage electrical device that limits the flow of current.
A line, which if its CBs are closed parallels two Receiving stations is known as a
A step up transformer is usually found at
stationary part of a disconnect is called the
Relays do not interrupt________ they _______ the CB
Advantages of relays
Relays operate under
Circuits are protected from faults by
Fuses and Relays
Parallel Circuit formula with only 2 or more resistors of un-equal value.
- Rt= __1___1____1__
- R¹ R² R³
Use common denominator and reciprocal