Electrical Grid 2 week 2

What is the main advantage of a three-phase system over a single-phase system?

• a 73% increase in power capability for a 50% increase in conductors

• generators, transformers, and motors are smaller and less expensive than single-phase equipment of the same rating

• less pulsating force applied to rotating generators and motors

• all the above

Answer explanation

section 2.1

True or false: The main difference between generating three-phase power and single-phase power, is that in 3 phase generation there is 3 coils, and single phase generation there is one.

• False

• True

Answer explanation

section 2.2

How many degrees apart are the coils of a three-phase generator spaced?

• 120 degrees

• 90 degrees

• 360 degrees

• 180 degrees

Answer explanation

section 2.2

True or False: Each coil of wire on the generator will produce its own voltage and current.

• True

• False

Answer explanation

section 2.2

Which of the following statements is true about three-phase power?

• It causes more fluctuation in power delivery.

• when one phase is at zero, the other two are providing power to the circuit.

• It is less efficient than single-phase power.

• It requires more energy to operate, like inertia to keep it spinning.

Answer explanation

section 2.3

What is the main difference between Delta and Wye configurations in three-phase connections?

• what type of wire is used in the coils.

• the amperage readings.

• the connection between the coils.

• the size of the coils.

Answer explanation

section 2.4

In a Wye system, how is the system voltage related to the coil voltage?

• System Voltage = Coil Voltage x 1.732

• System Voltage = Coil Voltage / 1.732

• System Voltage = Coil Voltage + 1.732

Answer explanation

section 2.5

In a Delta system, the coil voltage is ______ the system voltage.

• the same as

• twice

• 1.732 times higher than

• 1.732 times lower than

Answer explanation

section 2.5

What is the relationship between coil current and phase current in a Wye system?

• Coil Current = Phase Current

• Coil Current 1.732 times higher than Phase Current

• Coil Current 1.732 times lower Phase Current

Answer explanation

section 2.5

In a Delta system, the phase current is higher than the coil current by a value of 1.732.

• false

• true

Answer explanation

section 2.5