2-2-13 Conducting Transformer Load Checks (A)

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.

16.2kVA

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.

19.7 kva

According to the rule of thumb in the reference book, at 120 volts single-phase, there are ? available from a 25-kilovolt-ampere transformer.

207.5A

The tap setting on the side of the maximeter should be set to ? if placed on a 25-kVA single-phase transformer.

40/1

Overload peaks of ? do not affect a transformer.

5 min

Total phase current times line to neutral voltage equals kilovolt-ampere.

False

Twenty- to thirty-minute overload peaks are of no concern when conducting a load test.

False

Maximeters record the ? during the time of the test.

Highest load

A balanced load on a transformer is when ? .

both phase to neutral leads have the same load

When a maximeter is clamped around an energized conductor, never ? .

change taps on the meter

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

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.

true

A single-phase transformer should have a maximeter placed on each secondary lead from the transformer.

true

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

true

The red indicator needle on a maximeter indicates the load at the time of the reading.

true