Deck 6: Introduction to Polyphase Circuits

Question 1

A three-phase generator is smaller in physical dimensions than a single-phase generator.

Answer 1

True

Question 2

In a polyphase wattmeter, the ____________________ produced by two current coils and two voltage coils causes the pointer to deflect and indicate total watts in the circuit in one instrument.

Answer 2

Torque

Question 3

What is the least common type of polyphase system and what is it used for?

Answer 3

The least common type of polyphase system is two phase. It is used to power rectification.

Question 4

The power factor is the ratio of apparent power to true power.

Question 5

The A and B phase voltages in a two-phase connection are designed to be equal.

Question 6

The most common type of polyphase system is ____________________ phase.

Question 7

How can three-phase power be measured?

Question 8

In a(n) ____________________ connection, the windings are spaced 90° apart.

Question 9

What power factor value is the best electrical system?

Question 10

In the three-phase system, electrical energy originates from an alternator that has three main windings placed 180° apart.

Question 11

What must be used for the measurement of power in an unbalanced load?

Question 12

What is six-phase power usually applied to?

Question 13

____________________'s theorem paraphrased states: that a power system of N conductors can be measured by N-1 watt measuring elements.

Question 14

The two-wattmeter method can be used in an unbalanced three-phase, four-wire system.

Question 15

Three-phase windings may be connected either in the star (wye) pattern, or in the ____________________ pattern.