ELEC 13001

In a Wye connected system, the line voltage is equal to:

• Vp

• Vp × 1.732

• Vp / 1.732

• Vp × 2

When adding capacitors to a circuit to correct the overall power factor, the capacitors must be connected in:

• parallel with the load.

• series with the load.

• series with the source.

• parallel with the source.

Three 40-ohm resistors are connected in delta across a 220 Volt 60 Hz three-phase supply. The line current is:

• 9.53 Amps

• 5.5 Amps

• 16.5 Amps

• 22 Amps

Choose the equation that is best suited for a delta connected load that draws a line current of 37A.

• 37A × √3

• 37A / √3

• 37A × 2

• 37A / 2

Which of the following voltage characteristics is considered to be an ungrounded three-phase wye connection?

• 120/208V 4W

• 277/480V 4W

• 240/480V 3W

• 138/240V 3W

An unbalanced wye connected three-phase four-wire system has a line-to-line voltage of 600 Volts. The line-to-neutral voltage would be:

• 600 Volts

• 480 Volts

• 347 Volts

• 240 Volts

If a three phase generator has a negative phase sequence and rotates in a clockwise direction, which of the following represent the correct phase sequence

• ABC

• ACB

• BAC

• CBA

Power factor correction is used for which of the following?

• To reduce line loss and increase system capacity.

• To increase line loss and reduce system capacity.

• To increase reactive power in the system.

• To decrease the system voltage.

A delta-connected alternator has a rated voltage of 240 Volts per phase. The alternator is supplying a load of three 24 ohm resistors connected in wye. Calculate the line voltage.

• 120 Volts

• 208 Volts

• 347 Volts

• 240 Volts

When power factor correction capacitors are disconnected from the voltage supply:

• They remain charged indefinitely.

• Appropriate codes for discharge resistors must be enforced.

• They immediately discharge to zero.

• No special precautions are needed.