Practice Exam Flashcards
What is the unit of measurement for electrical power and what is the formula for finding it, in a resistive type circuit?
P = E x I
What is the formula for finding the total resistance of three loads connected in parallel?
1/R1 + 1/R2 + 1/R3 = 1/Rt
The ____________ enforces the Canadian electrical code?
CSA
Before an electrical contractor can install any electrical service to any type of HVAC & R equipment, the first document that must be obtained a
permit
The primary and secondary winding of a transformer:
are wired in series
are wired in parallel
are not physical connected
none of the above
are not physically connected
A current larger than normal, but flowing outside its normal current path is referred to as:
overload
over current
short circuit
ground fault
short circuit
A standard Code fuse will have an interrupting capacity of ___________amps.
10,000
100,000
200,000
none of the above
10,000
Thermal overload protection:
aids motor warm up
prevents motor from freezing
protects motor and conductors from mechanical damage
provides electrical protection of motors
protects motor and conductors from mechanical damage
An overcurrent is
a current above normal
a current shorted to ground
a short circuit
all of the above
a current above normal
A dual voltage delta connected three phase motor will have how many leads located in terminal box?
Question 20 options:
6
9
15
3
9
A current larger than normal, but flowing within its normal current path is referred to as an:
Question 23 options:
overload
recurrent
short circuit
ground fault
overload
In a pure inductive load circuit how many electrical degrees out of phase is the current with the voltage
Question 24 options:
90
270
160
30
90
The current the motor will draw at start-up is known as the:
Question 25 options:
full load amperage
rated load amperage
running load amperage
locked rotor amperage
locked rotor amperage
The primary and secondary winding of an auto transformer:
Question 26 options:
are wired in series
are wired in parallel
are not electrically connected
none of the above
wired in parallel?
The maximum current rating of a plug fuse is________amps.
Question 27 options:
25
30
40
15
30a
Which type of circuit breaker provides for both overload and short circuit protection:
Question 28 options:
thermal
magnetic
thermal-magnetic
any of the above
thermal-magnetic
In electrical circuits where devices are wired in parallel:
Question 29 options:
the total voltage is applied to each device
the total current flows through each device
the total resistance is the sum of all the resistors
all of the above
all of the above
What is the purpose of the normally open contact wired in parallel with the start button , in a push start and stop button ?
Question 30 options:
To restart the system once it has stopped.
It is used as a holding circuit as the start button is released.
There is no normally open contact in parallel with the start button.
To deenergize the coil in order to get the circuit restarted.
it is used as a holding circuit
A series circuit consists of three resistor. If one resistor is removed, and the remaining resistors are connected in series to the same source, then the current in each of these two resistors will be:
Question 32 options:
increased
decreased
the same as before
zero
increased
The amount by which the current leads or lags the voltage in an alternating current circuit is known as:
Question 33 options:
phase angle
induction angle
starting current
running current
phase angle
The term “slip” is______________________________________.
Question 34 options:
the amount of horse power available due to motor resistance
the difference between the motor full operational rpm rating and the speed of the rotating magnetic field.
the difference in motor rpm between the time the start winding circuit is opened and when the motor reaches full speed
the difference between the motor full operational rpm rating and the actual speed under load.
the difference between the motor full operational rpm rating and the actual speed under load
The normally open contact on a defrost timer is wired in series with the …..
Question 35 options:
Motor timer circuit.
Defrost heaters.
Cooling cycle.
There is no normally open contact on a defrost timer.
defrost heaters
If an open occurs in one branch of a parallel circuit, the line current (total current) will:
Question 38 options:
increase and the total circuit resistance will decrease
decrease and the total circuit resistance will increase
decrease and the total circuit resistance will decrease
be zero and the total circuit resistance will infinity
decrease and total circuit resistance will increase
Typical insulators are:
Question 39 options:
copper, silver, gold
brass, bronze, steel
glass, rubber, plastic
aluminum, nickel, magnesium
glass, rubber, plastic
IF fuses are used for overload protection, how many fuses are required for a 230 volts single phase compressor motor
2
Overload protection (fuse) for a hermetic motor compressor must not exceed \_\_\_\_\_\_ of FLA. Question 42 options:
120%
125%
115%
140%
125%
If a conductor carrying alternating current is formed into a coil, the magnetic field will:
Question 43 options:
be decreased
be increased
remain the same
be increased by 10 times
be increased
How would switches used as safety devices be connected with respect to the load they are protecting.
Question 44 options:
in series
in parallel
in series parallel
makes no difference
in series
The voltage rating of a conductor is determined by:
Question 45 options:
the size of the conductor
the type of insulation around the conductor
the application of the conductor
there is no voltage rating on conductors
type of insulation around the conductor
How much current would a 200 watt light bulb draw from a 120 volt source:
Question 46 options:
- 76 amps
- 67 amps
- 76 amps
- 67 amps
1.67a
I = W/E
What is the major difference between a contactor and a relay ?
Question 47 options:
The amount of current it can carry.
The amount of voltage flowing through it.
It is wired differently in a circuit.
The coil of a relay is wired in series with the start winding .
the amount of current it can carry
A coil of wire carrying alternating current produces a type of resistance known as:
Question 49 options:
capacitive reactance
capacitive inductance
inductive reactance
impedance
inductive reactance
In an AC resistive load circuit the current wave will always be in phase with the voltage wave and considered to have a power factor of 1.
Question 50 options:
True
False
true
The voltage rating of a fuse must be equal to or greater than the applied voltage of the circuit it is protecting.
Question 51 options:
True
False
true
As the current in a conductor decreases the magnetic lines of flux surrounding the conductor collapse inward.
Question 52 options:
True
False
true
The holding coil on a motor starter or contactor will always be the same voltage as the load circuit.
Question 54 options:
True
False
false
The locked rotor amperage of a motor is approximately 6 times that of the full load amperage.
Question 56 options:
True
False
true
The correct colour coding for single phase grounded 120 volt circuit would be black for line conductor, neutral, and a green or uninsulated ground.
True
False
true
As the current in a conductor is increased, the magnetic lines of force around the conductor also increase in concentration and in number.
Question 59 options:
True
False
true
A motor disconnect switch may be fused or unfused and are rated for voltage, and amperage according to the load of the circuit.
Question 60 options:
True
False
true
The most common starting device used on a PSC motor is the current relay or electronic.
true
false
false
Increasing the number of turns an electromagnet has, will increase the strength of the electromagnetic field.
Question 63 options:
True
False
true
A thermal type circuit breaker can be used if instantaneous response is required to overcurrents.
Question 65 options:
True
False
false
A motor disconnect for an outdoor condensing unit where the actual switch is located outdoors requires a watertight enclosure (NEMA 4) or (NEMA 3).
Question 66 options:
True
False
true
Another name for magnetic lines of force is magnetic flux.
Question 68 options:
True
False
true
The magnetism in an electromagnet is just as strong when the electrical current is not flowing as it is when the current is flowing.
Question 70 options:
True
False
false
On single phase 3 wire circuits the correct conductor color coding would be red and black for line conductors and white for neutral.
Question 71 options:
True
False
true
Magnetic lines of force start at the north pole and end at the south pole.
Question 72 options:
True
False
true
Impedance is the electrical term used to measure the total opposition to current flow in an AC circuit.
Question 73 options:
True
False
true
Cartridge type fuses come in single element form only.
Question 74 options:
True
False
false
Cartridge type fuses come in single element form only.
Question 74 options:
True
False
false
Contactors and relays are very similar as per their application and normally you will find relays used when the current draw of the controlled load is less than 20 amps.
Question 75 options:
True
False
true
Two resistors are connected in series to a 12 volt battery. One resistor is 4 ohms and the other resistor is 8 ohms. the voltage drop across the 4 ohm resistor would be:
Question 13 options:
zero volts
less then the voltage drop across the 8 ohm resistor
more than the voltage drop across the 8 ohm resistor
the same as the voltage drop across the 8 ohm resistor
less then the voltage drop across the 8 ohm resistor
