HVAC grade 10 DSA
Contactors are large relays and are used to control the operation of loads that draw more than ____ amps.
15
Split-phase single speed motors have____ windings.
2
Which type of motor requires a run relay?
CSCR
Which type of motor requires a start relay?
CSCR
The overload protector is usually wired in series with_____ on single-phase motors.
Common
I stands for what?
Current
A fan switch on a heating system would close on a temperature fall. True/false?
False because a fan switch turns on the fan on the temperature rise.
Heating thermostat contacts close on a temperature rise. True/false?
False because cooling thermostats close on a temperature rise.
True or False? The current in a circuit will decrease as the voltage is increased.
False because current and voltage are proportional in a circuit.
Single-phase power supplies always have a neutral wire.
False because if it is 240 volts, it does not need to have one.
When using a clamp-on ammeter the tongs should be clamped around both wires of a single-phase motor to get the proper reading. True/false?
False because one wire must be done at a time because two wires will cancel it out.
True or False? When a split-phase motor is running, both the start and the run windings must be energized.
False because the start winding is removed once the motor reaches 75% of its rated speed.
True or False? The start winding on a split-phase motor has a lower resistance that the run winding.
False because the start winding is thinner and longer than the run winding.
True or False? All overloads are usually open switches.
False because they are always closed, and only open during an overload altercation to save it.
A wooden ladder is safe to use around electrical equipment. True/false?
False because wooden ladders conduct electricity when wet.
The coil of a current relay is wired in what?
In series with the run winding
How are control transformers rated?
In volt-amps.
What does Ohm's Law talk about?
It talks about the relationship between amperage, voltage, and resistance.
Resistance represents what?
It's the opposition to flow of electrons, the diameter of the hose(R).
When checking resistance on a split-phase motor, common-to-run will the ____ ohm reading, common-to-start will the ____ ohm reading, and start to run will be the___ ohm reading.
Low, medium, and high
The proper name for a thermostat that can control multiple levels of heating and cooling is a____ thermostat.
Multi-stage
Resistance stands for what?
Ohms
Amperage represents what?
Quantity of electrons being released, current measured in amps( I )
A start capacitor is wired in _____ with the start winding of an electric motor.
Series
Before using a voltmeter you should?
Set the range selector to a higher voltage than the voltage you expect to read.
The windings are located in which part of the motor?
The stator
Voltage represents what?
Throw/ Amount of Pressure in the circuit (E)
Cooling thermostat close on a temperature rise. True/false?
True because a bi-metal expands on temperature rise.
True or False? The current is the same at all points in a series circuit.
True because current remains the same in a series circuit, but not in a parallel circuit.
True or False? Heating anticipators are wired in series with the heating thermostat contacts.
True because it is designed to turn the heat off prior to its' set point.
True or False? Shaded-pole motors have no start and only run windings.
True because it uses a copper band in place of the start winding.
True or False? A necessary safety practice for a technician is to keep a padlock with only one key in the tool box.
True because it's a safety procedure known as the lock out tagout drill.
True or False? It is possible to have a control relay with a 24-volt coil and 220-volt contacts.
True because the coil relay has nothing to do with the contacts other than change its position.
True or False? Run capacitors are filled with oil and are enclosed in a metal case.
True because the metal casing helps cool down the capacitor.
True or False? If a conductor carrying electrical current is formed into a coil, the strength of the magnetic field generated by the wire will increase.
True because the more coils, the more strength is in the magnetic field.
True or False? The total resistance of a parallel circuit is always less than the value of the lowest resistance in the circuit.
True because the reciprocal formula supports that statement.
True or False? When a split-phase motor is starting, both the start and the run windings must be energized.
True because the start winding provides starting torque.
When soldering/brazing, safety glasses should be worn at all times. True/false?
True because you need to protect your eyes 24/7.
Quite, often insurance companies will reject claims for injuries that were sustained as a result if improper dress. True/false?
True because you weren't wearing the appropriate work attire.
E stands for what?
Volts
The coil of a current relay is wired_______
in series with the run winding.
The amperage rating of a contactor is_______
more than the relay.
Shaded pole motors are rated in?
watts
