section 10 lesson 6

Utilities normally generate ? .

3 phase AC power

How much power in kilovolt-amperes is delivered to a 3-phase transformer when the line voltage applied is 480 volts and the line current is 12 amps? (Round the FINAL answer to two decimal places.)

9.98 kVa

In a 3-phase circuit, power varies during a cycle but never falls to zero.

true

Magnetic force is used to rotate the coils in a generator.

false

Transformers are usually used to step up voltage at the point of use.

false

A ? produces energy when a rotating coil cuts through magnetic flux.

generater

A(n) ? is a machine that converts mechanical energy into electrical energy by means of electromagnetic induction.

generator

? is a method of synchronizing generators.

lights-out

The ? is the current flow through the lines to a load.

line current

The ? is the voltage measured line-to-line.

line voltage

What was the primary transmission line problem that led up to a sequence of events that eventually caused the East Coast power blackout on August 14, 2003?

sagging line shorted

A(n) ? is a device that indicates whether two AC sources to be connected in parallel are in the correct phase relationship.

synchroscope

A landfill generator runs on the methane gas created by decomposing trash.

true

A stronger magnetic field, more turns, and faster rotation produce a higher voltage from a generator.

true

In the three-lights-out method, a lamp is connected as a load across each phase of the two sources, A to A, B to B, and C to C.

true

The most efficient way to send electric power over transmission lines is at the lowest current possible.

true

The power in a single-phase circuit drops to zero ? every cycle.

twice

Which factors determine the amount of voltage produced by a generator? I. The number of turns II. The speed of rotation of the rotor III. The strength of the magnetic field IV. The load on the generator

1, 2, 3

If the line voltage is 480 volts as shown, the winding voltage is ? .

277V

In North America, power is generated at a frequency of ? .

60hz

The ? is the current flow through the individual windings.

winding current

The ? is the voltage measured across the windings.

winding voltage

In an electric generating power plant, all generators must be connected in ? .

parralel