Electric test
100 milliamps is equal to ____ amperes
0.10
Relays used in the HVAC industry are generally used to control loads up to ____ amps.
10
Three 300 ohm resistors are wired in parallel. The total resistance equals...
100 Ohms
2.1 KW is equal to ____ watts
2100 Watts
How many watts of power are used by a heater operating at 460 volts and drawing 5 amps?
2300 Watts
Utility companies usually supply residential homes with _________service.
240V, single phase, three wire
Three defrost heaters, each 15 ohms are wired in parallel to a 120 volt power supply. How many watts of power will be used?
2880 Watts
How many watts of power are used by a heater operating at 240 volts and drawing 15 amps?
3600 Watts
What is generally considered to be the maximum allowable (plus or minus) supply voltage variation?
5%
A parallel circuit contains an 18 ohm and a 9 ohm resistor, The total resistance equals ____ ohms
6 Ohms
A parallel circuit consists of three resistors. R=30ohms R2=15ohms R3=10ohms If the current through R2=4 amperes, what is the source voltage?
60v
One horsepower is equal to ____ watts?
746
Three resistors are wired in series. Each has a value of 300 ohms. What is the total resistance of the circuit
900 Ohms
An ohmmeter should never be connected to:
A live circuit
A capacitor analyzer is designed to read the ____ of a capacitor?
Capacitance
Any material that will readily release electrons is called
Conductor
Contactors are rated according to the maximum amperage through the
Contacts
The symbol for ____ is I
Current
When the temperature of a negative temperature coefficient (NTC) thermistor increase, its resistance will...
Decrease
Which of the following motors is most energy efficient?
ECM
A soleniod valve operates on the principal of
Electromagnetism
The safety ground conductor is usually color coded ____ or ____
Green, bare
In electrical wiring, a black colored wire in an alternating current circuit usually indicates the ____ _____
Hot conductor
Voltage can be calculated by:
I times R
When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance will...
Increase
The total resistance of a parallel circuit will be ____ than the smallest resistance.
Less
What connections to the terminals T1, T2, & T3 on a contactor or motor starter
Loads
The thermal overload contacts on a line starter are usually __________reset.
Manual
Capacitors are rated in;
Microfarads and volts
An electron has a ____ charge
Negative
An electron has
Negative charge
What would be the result, if a 24 volt, 20-ohm low voltage contactor coil were wired in series with a 24 volt, 200-ohm control relay coil?
Neither because they share voltage
What meter is used to bench check a motor for shorts or open windings?
Ohmeter
Which meter must use its internal power to check a load or circuit?
Ohmeter
What is impedence?
Opposition to alternating current flow.
The ____________drawing illustrates where the components are located on the appliance.
Pictorial
Like charges will _______ each other
Repel
When resistors are wired in parallel the voltage drop across each resistor will be the ____ as the applied source voltage
Same
Silicon would be best suited for use as a ____
Semiconductor
In a ____ circuit, the voltage drop across each resistance (load) will add up to equal the source voltage.
Series
Direction of rotation of a single phase induction motor is determined by...
The direction of the current flow through the start winding
What is current flow?
The flow of electrons in a circuit
A three phase system requires a minimum of
Three supply lines
On an electronic oil safety switch what changes the pressure signal to electrical signals?
Transducer
To discharge a capacitor prior to ohmmeter testing...
Use a 20,000 ohm resistor to short across the terminals
A step up transformer increases;
Voltage
How are fuses sized?
Volts and Amps
The meter on a house measures the _______ passing through it.
Wattage
A capacitor opposes current flow in a circuit. This opposition is called;
capacitive reactance
To change direction of rotation of a three phase motor
change the position of any two supply wires.
Direction of rotation of a single phase induction motor is determined by;
the direction of current flow through the start winding
