8-11 123

__________________ magnetism is created when a piece of iron is placed in a magnetic field.

Induced

____________ poles of magnets repel each other.

Like

__________ has established standard motor dimensions.

NEMA

____________ motors are used when very small starting and running torques are required.

Shaded pole

_______________________ is the strength that a motor produces by turning, either while starting or running.

Torque

A contactor is used to control an electrical load in a control system.

True

A cooling thermostat closes on a rise in temperature.

True

A load that is purely resistive in nature with no coil to cause induction is called a resistive or non-inductive load.

True

Contactors are rated by the amperage they can carry.

True

Contactors are used on larger loads than relays are because their contacts are larger.

True

Contactors are used to make and break a set of contacts that control the voltage to loads in heating and air conditioning systems.

True

Contacts are made of silver or cadmium which will resist sticking

True

Fuses are primarily used to protect non-inductive loads that do not draw LRA on start up.

True

If the VA rating of a transformer is 75 VA and the output voltage is 24 volts, the maximum amperage the secondary can handle without overheating is 3.1 amps.

True

If the contactor contacts become burned and pitted it is possible that they could develop resistance and cause a voltage drop.

True

If you check a single phase compressor motor and it is experiencing difficulty starting up, you can add a correctly sized start capacitor and potential relay to the electrical circuit and increase starting torque and possibly repair the compressor.

True

Overloads can be divided into two basic groups, thermal and magnetic.

True

The VA rating of a transformer divided by the low voltage output determines the maximum amps the secondary output can support without overheating.

True

The back electromotive force is the amount of voltage that is produced by the start winding of a motor while it is operating.

True

The back electromotive force is the controlling factor that causes a potential relay to drop the start winding out of the circuit once a single phase motor is up and running 75% full speed.

True

The chemical composition of contacts is such that they operate at cool temperatures of up to 125% of their current-carrying capacity.

True

The contacts in a remote bulb thermostat open and close contacts when the pressure in the bulb raises and lowers due to temperature changes.

True

The controlling element of a thermostat is the part that moves when a change in temperature is sensed.

True

The current relay, also known as the magnetic relay, is built like a solenoid, with a copper wire wrapped around a hollow steel core holding a steel plunger.

True

The difference between line voltage and low voltage thermostats is the amount of current they can carry.

True

The function of a thermostat is to make and break power to loads based on the temperature in a structure.

True

The pilot duty overload directly breaks the line voltage to a motor or load.

True

The potential realy is easy to check because there are only 2 components that need to be checked on it.

True

The simplest form of overload protection is a fuse.

True

The transformer for a residential air conditioning system is used to convert line voltage to 24 volts.

True

Transformers are rated by their primary voltage, secondary voltage, and voltamperes (VA).

True

Transformers are stationary devices that transfer electrical energy from one circuit to another by induction.

True

With the advancement of solid state starting relays, there is a start relay available now that has no moving parts called a PTC device.

True

The _____________________ consists of two aluminum plates with an insulator between them.

capacitor

The _____ motor produces a high starting torque, which is needed for many applications in the industry.

capacitor-start

The _____________ is a magnet produced through electricity.

electromagnet

The magnetic lines of force of a magnet that flow between the two poles are called _______________.

flux

The rotation of a shaded-pole motor is determined by _____.

location of shaded pole

The area that the magnetic force operates in is called a/an ________________.

magnetic field

_________________________ is the physical phenomenon that includes the attraction of an object for iron.

magnetism

A _______________ is the unit of measurement for the strength of a capacitor.

microfared

When going on a service call, the technician's appearance is _____________.

of utmost importance

To make an electric motor move continuously, there must be a ______________ magnetic field.

rotating

The ______ is the part of a motor that spins.

rotor

The ___________ capacitor is designed to stay in the motor circuit for the entire cycle of operation.

run

The capacitor- _____________ motor produces a high starting torque.

start

The_______________ is the stationary part of a motor.

stator

One of the most important aspects of the technician's job is _____.

the treatment of the customer

A heating thermostat closes on a rise in temperature.

False

A very common overload used in the industry is the bi-metal overload that uses three different metals to make a temperature sensitive device that moves contacts by expanding and contracting with temperature changes.

False

Coil characteristics depend on the type of wire but not the manner in which it is wound.

False

In an open type split phase, single phase motor, the start winding must be dropped out of the circuit once the motor is up and running at 35% full speed.

False

Inductive loads do not draw higher amperage at start up than they do once they are running full speed.

False

Most residential and small commercial HVAC systems use a 12 volt control system.

False

On all single phase motors, the starting amperage is less than the running amperage because the motor only stays in start mode for a second or so.

False

Relays are designed to carry more current so they are used on larger loads than contactors.

False

Relays can not be used to control loads in an HVAC system.

False

Split phase motors have a start and run winding that both stay energized the entire time the motor is operating.

False

The 3 primary parts that make up contactors and relays are the contacts, coil, and electrical connection points

False

The bi-metal thermostat gets it's name from the fact that it uses three similar metals.

False

The exact temperature in a structure can be maintained by a transformer.

False

The low voltage thermostat can carry more current than the line voltage thermostat.

False

The pilot duty overload directly breaks the line voltage power to motors and loads.

False

The primary winding in a thermostat induces a output voltage in the secondary.

False

The primary winding of a transformer is the output side of a transformer.

False

The running load amperage, RLA, is sometimes stated as the LRA on a motor nameplate.

False

The secondary winding of a transformer is the input side of a transformer.

False

The thermostat in a heating and air system provides the low voltage power for the control circuit.

False

Thermal overloads will trip and stop the load from operating when the magnetic field created in the circuit increases above the design trip point.

False

Transformers are 100% efficient

False