Worksheetstransformers week 2
Total questions: 26
Worksheet time: 13mins
when interpreting primary coil rating of a transformer, what number (whether printed first or last) is the number that needs to be impressed on the primary coil for proper operation
the larger number of the voltages
the phase to phase voltage
the smaller number of the voltages
the phase to ground voltage
if a transformer coil rating is printed after the system voltage, eg. (20800 GRDY./12000) the transformer will it have______________________ and it will be connected ____________.
one bushing, phase to ground
two bushing, phase to phase
the bushing, phase to ground
one bushing, primary
which is NOT a primary voltage designation for a transformer?
phase to phase connections only
phase to phase or phase to ground connections
phase to ground connections only
ground to ground connections only
as listed in the text which is clearly the most versatile transformer?
phase to phase connections only
phase to phase or phase to ground connections
phase to ground connections only
phase to ground or phase to phase dual rated
T or F. when a transformer nameplate only lists one voltage on the high voltage section, the transformer must be wired in a delta configuration
True
False
engineers can choose from ___________different primary voltage designations when purchasing transformers
2
3
4
5
T or F. A tap changer is a no load switch connected to the secondary coil
True
false
the dual voltage switch of a transformer can be operated while energized
True
False
if high cost voltage regulation is not practical, which is an option most likely to be considered by a company?
capacitors
dual rated transformers
tap changing transformers
reactor
by what amount does the tap changer raise or lower the secondary voltage?
2.5% or 4.2%
2.5% or 4.5%
4.5% or 5.5%
5/8% each step
________________ the integrity of a transformer prior to installation is always recommended
checking
proving
testing
verifying
schematics show the primary and the secondary coils and their relationships
true
false
what should always be done before connecting the customers load
verify secondary voltage
nothing
contact customer
verify secondary voltage with an approved voltmeter
this type of transformer test equipment is sometimes referred to as a megger
continuity tester
transformer last check
insulation tester
turns ratio tester
while performing a continuity test, and audible sound should be heard between the primary and secondary windings
true
false
for this type of test, the low-input voltage must be connected to the high voltage windings
turns-ratio
continuity
insulation
oil quality
the most important part of a transformer is the __________
ground lug
tank
bushings
nameplate
of the answers listed below, pick all that can be found on a transformer nameplate
voltage rating
PCB levels
Schematic
kilovolt-amperes
impedance levels must be within what percentage if banking
2.5-4.5%
+/- 10%
+/- 5%
matching
according to the text, when the coil rating is printed after the system voltage, the transformer will have one bushing
True
False
which answer would fit if it is made for phase to phase connections only?
have one primary bushing
are suitable for a grounded wye system
have a voltage rating that only depicts one number
the nameplate on an over head transformer can usually be found where
on or near the top mounting bracket
the lid
on or near the lower mounting bracket
on the case
if there are two numbers listed on the HV portion of a transformer nameplate, which is the primary coil rating?
both
bigger
smaller
Hastings manufactures a transformer tester called "TLC Meter" what does TLC stand for
tender loving care
transformer light care
testing light check
transformer last check
what is the order of the secondary bushings on an additive polarity transformer?
X1 X2 X3
X3 X1 X2
X3 X2 X1
X1 X3 X2
when referring to the nameplate which is incorrect?
ensure that the desired secondary voltage is chosen
determining the weight for rigging purposes
ensuring the impedance is +/- 12% for banking
ensure that desired primary voltage is chosen
