Electricity week 2

The voltage at the 90-degree point of a sine wave with a maximum voltage of 10V is _____.

+10V

The effective (rms) voltage of a sine wave with a peak voltage of 200V is _____

141.4

Run capacitor

A capacitor that remains in the motor circuit while the motor is running to im-prove running efficiency.

Fusible link

A circuit protective device that melts, opening the circuit, when the current is excessive.

240 and 480 VAC

A closed-delta three-phase distribution system produces _____.

Alternator

A device that generates alternating current by means of conductors rotated in a mag-netic field.

protect the secondary from excessive current

A fusible link may be used to _____.

Dielectric

A material that strongly resists the passage of current.

Megohmmeter (megger)

A test instrument used to test high-resistance circuits

residential gas furnace

A transformer with a 120VAC primary and a 24VAC secondary would be found in a _____.

isolation transformer

A transformer with a 1:1 turns ratio that is used to isolate circuits is called a(n) _____.

Isolation transformer

A transformer with a one-to-one turns ratio. It is used for personnel safety and to prevent electrical interference.

Induction motor

An AC motor

Less Pulsation

An advantage of a three-phase motor over a single-phase motor is _____

Capacitor

An electrical storage device contain-ing two metal plates separated by an insulating (dielectric) material.

Resistive

Electric heating elements in a heat pump are examples of _____ circuits.

40V

If a transformer has 600 primary windings and 200 secondary windings, what will be the output voltage with an input of 120VAC?

155.5 V

If the effective voltage is 110V, what is the peak voltage?

Qualified person

One who has the skills and knowledge related to the construction and op-eration of electrical equipment and installations, and has received safety training to recognize and avoid the hazards involved.

Microfarad

One-millionth of a farad. Used to rate capacitors.

Torque

The force that must be generated to turn a motor.

2 percent

The maximum allowable leg-to-leg voltage imbalance in a three-phase system is _____.

Synchronous speed

The maximum rated speed of a motor. Torque

Commutator

The movable contact surface on an electric generator or motor

Frequency

The number of complete cycles of an alternating current, sound wave, or vibrating ob-ject that occur in a period of time

Turns ratio

The ratio between the number of turns in the primary and secondary windings of a transformer. S

Good Motor

The resistance to ground of a 460V motor is measured at 500,000Ω ohms. This indicates a(n) _____.

Armature

The rotating component of a genera-tor.

Rotor

The rotating component of an induction motor.

Stator

The stationary windings of a motor

Inductive

The stator of a single-phase motor is an example of a(n) _____ load.

Run winding

The stator winding of a motor that draws curr.ent during the entire running cycle of the motor.

Start winding

The stator winding of a motor that is used to provide starting torque

Inertia

The tendency of a body in motion to re-main in motion and a body at rest to remain at rest.

capacitor start-capacitor run

The type of single-phase motor commonly used to drive compressors is the _____.

Hertz (Hz)

The unit of measure for the frequency of alternating current. One Hertz equals one cy-cle per second.

Effective voltage

The value of AC voltage that will produce as much power when connected across a load as an equivalent amount of DC voltage. Also known as root-mean-square (rms) voltage

Root-mean-square (rms) voltage

The value of AC voltage that will produce as much power when connected across a load as an equivalent amount of DC voltage. Also known as effective voltage.

Sinusoidal (sine) wave

The waveform created by an AC generator. ost

Induction

To generate a current in a conductor by placing it in a moving magnetic field.

100mA

What is the threshold current level at which a fatal shock can occur?

prevent the ohmmeter from reading the resistance of a parallel circuit.

When making continuity checks, one end of the circuit being tested is disconnected in order to _____.

with one lead on the line side of the fuse and the other lead on the load side of another fuse

When testing a fuse with power applied, the voltmeter leads are connected_____.

A disconnect is required for a condensing unit branch circuit in addition to any fuse or circuit breaker.

Which of the following is a correct statement regarding power supplied to a condensing unit?

Four-Wire Eye

Which of the following three-phase configurations will provide 480V?

Three-Phase

Which type of induction motor does not have a start winding?

Shaded pole

Which type of single-phase motor produces the lowest starting torque?

Split-Phase

Which type of single-phase motor uses a centrifugal switch to control its starting circuit?

240VAC

With an Edison hookup, the voltage measured between L1 and L2 should be _____.