This type of fuse is used as a relay or metering potential
transformer fuse or 4.8 kV ground detector transformer fuse
Glass-Liquid filled fuse
True/False
Fused disconnects (or any other type of disconnect) should not be used to interrupt the load of station service transformers
True
This consists of a small metal tank filled with insulating oil. A fusible link is mounted in a carrier and submerged in the oil.
These devices are still used in some of our older stations on the
4.8 kV supply side of station service transformers
OIL FUSE CUT-OUT
These devices may be installed in “temporary” style stations.
BOXED FUSE CUT-OUT
True/False
Equipment suspected of being faulted should not be re
energized for test by means of replacing fuses or closing fused
disconnects
True
When replacing fuses by hand with the fuse holder de- energized, rubber gloves must be worn at voltages below 7.5kV and done with two
Qualified Electrical Workers
True/False
At voltages 7.5kV and above, the circuit must be grounded and under a clearance before replacing fuses by hand.
True
True/False
Manually operated LIDs and circuit switchers must never be “cracked” as are ordinary disconnects. A smooth, continuous, rapid motion is required for the interrupter mechanism to function properly.
True
What substance is used in the Arc Chamber, and what is an indicator that the substance useful life has exhausted.
Powder, noisy operation
What are some of the risk/dangers of paralleling regulators one step of neutral.
Excessive and dangerous circulating current will result which may cause equipment damage, personnel injury, or relay operations
What an operator do if ESM cannot determine the neutral on a regulator
notify the LD
drop the load
isolate the regulators
pick up the load on the transfer bus
Issues clearance to ESM
If the surge arrestor is damaged (regulator) what could this mean?
It could be a direct result of internal arcing
A transformer bank which is giving a “main tank” low level alarm on a very cold night and which, on inspection, does not exhibit evidence of a large oil leak may not yet have critically low oil, what should the operator do?
The Operator should use his good judgment. Taking the bank off till ESM can add oil is appropriate if operating conditions permit.
True/False
A low level indication (or alarm) at the LTC compartment of a
transformer bank may be the result of a serious leak from the LTC compartment into the main tank
True
The LTC level (oil) may be critically low without evidence of an external leak. why?
The oil from the LTC compartment may be leaking into the main tank
What does it mean when an excessive amount of oil is thrown following a relay operation.
It means that the CB interrupted high values of fault current
True/False
Dark or blackened oil in a CB sight glass may indicate carbon
contamination of the oil, which reduces its dielectric strength
True
If a worker bids a Clearance on this type of CB and the bid does not specify that air be left in the receiver, the Operator should follow the following procedure in addition to opening appropriate disconnects
-The air tank supply valve must be closed and left closed.
-The DC control switch and low pressure alarm switch must be opened and left open.
-The air tank must be completely drained of air by opening and leaving open it’s drain valve.
-The air tank supply and drain valves must be properly tagged to prevent further valve operation
True/False
Manual closing of the external isolating switch blades without air in the tank will cause the trip coil to burn out if the DC control switch is in the closed position
True
A “co-generation facility” consists of a connected to our system, located in the field, owned and operated by a DWP customer
generator
True/False
“All personnel shall wear approved hearing protective devices while in the same room with air blast CBs or within 20 feet of air blast CBs located outdoors.”
True
True/False
Gas Cylinders should be store upright and protected from from falling, violent blows, and excessive heat whether full or empty
True
Cylinders containing different gases must be stored
