3rd year level 1 lesson 5

73%

By stringing a fourth wire and reconnecting the substation transformer secondaries from delta to wye, the capacity of the circuit can be increased by ? .

False

In a delta connected 3-phase system, the line current is equal to the phase current.

Only one voltage is available between any two wires

In a delta system, ? .

1.73

In a delta system, the line current is equal to ? times the phase current.

False

In a wye connected system, the amount of voltage from the tip to the center of the Y (across a single winding) is known as the line voltage.

1.73

In a wye connected system, the line voltage is equal to ? times the phase voltage.

Line

In a wye connected system, the voltage from tip to tip (between the lines) is known as the ? voltage.

58%

The current flow in a wye circuit is about ? less than in an equivalent delta circuit.

3 wire

The delta system is also called a ? system.

Y

The two basic types of 3-phase distribution systems are symbolized by a delta symbol (Δ) and a(n) ? .

12470 Y

When a 3-phase, 3-wire, 7,200-volt delta circuit is cut over to a 3-phase, 4-wire wye circuit, the line voltage is ? .

Phase

In a delta system, the line voltage and the ? voltage are the same.

True

In a delta system, the three phases are connected in series.

True

The most commonly used 3-phase distribution system is the wye system.

7,200/12,470Y V

The most popular distribution voltage in use today is the ? system.

Wye

When a 3-phase transformer bank is connected in a ? configuration, one end of each coil is connected together at a common point.

200 amps

If the line current in a wye system is 200 amperes, the phase current is ? .

2400 wye

If the line voltage in a delta system is 2,400 volts, the phase voltage is ? .

346 A

If the phase current in a delta system is 200 amperes, the line current is ? .

120 V

If the phase-to-phase voltage in a wye system is 208 volts, the phase-to-neutral voltage is ? .

Phase

The voltage measured across a single winding or phase is known as the ? voltage.

120 degrees

The voltages of a 3-phase system are ? out-of-phase with each other.

4 wire

The wye system is also called a ? system.

False

There are three different voltages available in a wye connected system.