3-1-14 Question and answers 100%
correct 2025
Under a balanced load condition, the primary transformer coils of a closed
delta bank each draw 20 amperes. The current through each of the primary
leads is ? .
a.17.3 A
b.20 A
c.28.9 A
d.34.6 A - correct answer ✔D. 34.6A
Wye-delta transformer banks can be connected with either 30° or 120°
angular displacements.
Select one:
True
False - correct answer ✔False
A closed wye-delta transformer bank supplies 240-volt, 3-phase power and
120/240-volt, single-phase power on a 4-wire service line. If the single-phase
load is 36 kVA, the transformer with the grounded X2 bushing will supply ? of
that load.
a.12 kVA
b.24 kVA
c.30 kVA
d.36 kVA - correct answer ✔B. 24 kVA
, To supply 480-volt, 3-phase power with the transformer secondary coils
banked in a wye configuration, the transformer secondary voltage ratings
must be ? .
a.208 V
b.277 V
c.416 V
d.480 V - correct answer ✔B. 277 V
To provide a 347/600-volt, 3-phase service, transformers with a secondary
voltage rating of ? must be ? banked.
a.347 V / delta
b.347 V / wye
c.600 V / delta
d.600 V / wye - correct answer ✔b. 347 V / wye
A closed transformer bank supplies 240-volt, 3-phase and 120/240-volt,
single-phase power. With a single-phase load of 30 kVA and a 3-phase load
of 60 kVA, the total load on each of the power pots is ? .
a.20 kVA
b.26 kVA
c.30 kVA
d.40 kVA - correct answer ✔C. 30 kVA
An open transformer bank supplies 3-phase power on a 3-wire service line.
The transformers are each rated at 25 kVA. The power rating of this bank
is ? .
a.25 kVA
b.37.5 kVA
correct 2025
Under a balanced load condition, the primary transformer coils of a closed
delta bank each draw 20 amperes. The current through each of the primary
leads is ? .
a.17.3 A
b.20 A
c.28.9 A
d.34.6 A - correct answer ✔D. 34.6A
Wye-delta transformer banks can be connected with either 30° or 120°
angular displacements.
Select one:
True
False - correct answer ✔False
A closed wye-delta transformer bank supplies 240-volt, 3-phase power and
120/240-volt, single-phase power on a 4-wire service line. If the single-phase
load is 36 kVA, the transformer with the grounded X2 bushing will supply ? of
that load.
a.12 kVA
b.24 kVA
c.30 kVA
d.36 kVA - correct answer ✔B. 24 kVA
, To supply 480-volt, 3-phase power with the transformer secondary coils
banked in a wye configuration, the transformer secondary voltage ratings
must be ? .
a.208 V
b.277 V
c.416 V
d.480 V - correct answer ✔B. 277 V
To provide a 347/600-volt, 3-phase service, transformers with a secondary
voltage rating of ? must be ? banked.
a.347 V / delta
b.347 V / wye
c.600 V / delta
d.600 V / wye - correct answer ✔b. 347 V / wye
A closed transformer bank supplies 240-volt, 3-phase and 120/240-volt,
single-phase power. With a single-phase load of 30 kVA and a 3-phase load
of 60 kVA, the total load on each of the power pots is ? .
a.20 kVA
b.26 kVA
c.30 kVA
d.40 kVA - correct answer ✔C. 30 kVA
An open transformer bank supplies 3-phase power on a 3-wire service line.
The transformers are each rated at 25 kVA. The power rating of this bank
is ? .
a.25 kVA
b.37.5 kVA
