2-2-8
The tap setting must always be set at ? before a distribution transformer is put into service. Select one: a.100% b.104% c.full d.neutral
A. 100 %
As the primary voltage drops, one would ? the percentage on the tap changer to raise the secondary voltage. Select one: a.bridge b.lower c.raise d.separate
B. Lower
The ? tells how to connect a transformer for the voltage involved. Select one: a.job blueprints b.job specifications c.nameplate d.utility safety guidelines
C. Nameplate
A distribution transformer with taps has its primary in ? . Select one: a.1 coil b.1 coil, multiple taps c.1 coil, tapped d.2 coils
D. 2 coils
Aluminum links or straps are used to make the connections on a transformer terminal board. Select one: True False
False
A dual voltage transformer is designed to operate on one of two different primary voltages. Select one: True False
True
Double-bushing tapped transformers normally have one tap above 100% in order to lower the secondary voltage. Select one: True False
True
In all tap settings on a transformer terminal board, 3 and 4 are always connected together. Select one: True False
True
Older transformers (pre-1959) had all the taps below 100% in order to always increase the secondary voltage. Select one: True False
True
One reason to be careful when changing internal taps on a transformer is that PCBs may be present in the oil. Select one: True False
True
Ratio adjustment of a distribution transformer is accomplished by the use of a tap changing switch. Select one: True False
True
The primary coils of a dual-voltage transformer can be connected in series or in parallel. Select one: True False
True
Before operating the tap-changing switch on a distribution transformer, it must be ? . Select one: a.at full load to see the difference made b.at minimum secondary load c.deenergized from all sources of energy d.energized either from the primary or the secondary
c.deenergized from all sources of energy
With the coils connected in series, a dual-voltage transformer will operate on ? . Select one: a.a delta system only b.a wye system only c.the higher of the two voltages d.the lower of the two voltages
c.the higher of the two voltages
On a 2,400-volt primary winding transformer, if the primary line goes up to 2,508 volts, in order to lower the voltage to 120/240 volts on a distribution transformer, the tap selector would be set to ? . Select one: a.94% b.96% c.100% d.104%
d.104%
The most common dual-voltage distribution transformer is rated at ? . Select one: a.2,400 × 4,160Y - 120/240 b.4,160 × 7,200 - 120/240 c.7,630 × 13,200 - 120/240 d.14,400 × 7,200 - 120/240
d.14,400 × 7,200 - 120/240
A customer served by a transformer fitted with a tap changer has low voltage. A recording voltmeter indicates an average 114 and 228 volts. To provide the customer with the proper 120- and 240-volt service, the tap must be changed from the number III 100% position to the ? position. Select one: a.I 105% b.II 102.5% c.IV 97.5% d.V 95%
d.V 95%
