Unit 2-2 Lesson 13

A 15-kVA single-phase distribution transformer shows 75 amperes on X1 and 60 amperes on X3. Voltage is 120 volts from each secondary bushing to the neutral. The transformer has exactly ? of load. a. 10.6 kVA b. 16.2 kVA c. 19.2 kVA d. 22.5 kVA

B

The tap setting on the side of the maximeter should be set to ? if placed on a 25-kVA single-phase transformer. a. 20/1 b. 40/1 c. 100/1 d. the highest scale

B

When a maximeter is clamped around an energized conductor, never ? . a. bump the meter b. change taps on the meter c. tape the meter in place d. turn the meter with the dial up

B

A 15-kilovolt-ampere transformer is checked and is carrying 19.5 kilovolt-amperes; it should be reported as overloaded. Select one: True False

True

A load test taken with a clip-on ammeter and a multimeter will indicate if a transformer is overloaded at the time of the test. Select one: True False

True

Since a single-phase distribution transformer has two secondary coils, it is possible for only one coil to be overloaded. Select one: True False

True

The red indicator needle on a maximeter indicates the load at the time of the reading. Select one: True False

True

Twenty- to thirty-minute overload peaks are of no concern when conducting a load test. Select one: True False

True

Overload peaks of ? do not affect a transformer. a. 5 minutes b. 10 minutes c. 30 minutes d. 60 minutes

A

An engineer wants an accurate spot load check on a single-phase service. The A conductor has 115 volts and 95 amperes, and the B conductor has 113 volts at 78 amperes. There is ? being pulled off the transformer. a. 15.6 kVA b. 19.7 kVA c. 25 kVA d. 33.5 kVA

B

According to the rule of thumb in the reference book, at 120 volts single-phase, there are ? available from a 25-kilovolt-ampere transformer. a. 110 A b. 115.6 A c. 207.5 A d. 244.6 A

C

Total phase current times line to neutral voltage equals kilovolt-ampere. Select one: True False

False

A single-phase transformer should have a maximeter placed on each secondary lead from the transformer. Select one: True False

False

A balanced load on a transformer is when ? . a. both phase to neutral leads have the same load b. both phase to neutral leads have the same voltage c. the kVA of the transformer is at its maximum d. the kVA of the transformer is not reached

A

Maximeters record the ? during the time of the test. a. highest load b. highest voltage c. hours the line is energized d. normal current drawn off the transformer

A