Practical Electricity D2L

Question 1

True or False;
A safe distance must be maintained when working near overhead power lines.

Answer 1

True

Question 2

Where are line lugs in an electrical disconnect supposed to be located according to the electrical code?

Answer 2

Top of the disconnect

Question 3

True or False;
When a disconnect is open the line lugs at the top are still live and should be treated as such.

Answer 3

True

Question 4

Where is the best place to find how to safely lock out a piece of equipment?

Answer 4

The lockout procedure determined by the employer

Question 5

What is the order required to safely lockout a piece of equipment.

Answer 5

1.LOCATE sources of energy
2. DETERMINE HOW TO isolate each power source
3.ISOLATE each energy source
4. Apply LOCKS and TAGs to each lockout point
5. TEST successful lockout by trying to start the machine.

Question 6

Which type of breaker is designed to protect against severe and light overload conditions?

Answer 6

Thermal/Magnetic circuit breakers feature a thermal tripping mechanism as well as a magnetic tripping mechanism. This means that the protective devices trip faster in the event of a short circuit compared to thermal fuses.

Question 7

What effect does moisture or dirt have on the insulation around a conductor?

Answer 7

Reduces the resistance

Water = conductor
Dirt = I am not sure

Question 8

What classification of fire extinguisher is required to put out an electrical fire?

Answer 8

Class C

Ceeeeelectrical

Question 9

What would happen to a machine that had a supply voltage that was lower than it’s design voltage?

Answer 9

Increased Amp Draw

Question 10

True or False;
Breakers should only be used at or below their ratings, unless they are continuously monitored by an electrician

Answer 10

False
Should never use breakers over their ratings.

But, breakers should be used at or below their rating.

Question 11

True or False;
Stop buttons have normally closed contacts that allow current flow until they are pressed.

Answer 11

True

Question 12

What type of current limiting device is filled with sand to suppress the arc that occurs when the fuse blows?

Answer 12

HRC
(high rupturing capacity)

Question 13

What type of fuse is used to prevent over amperage of an electrical motor?

Answer 13

Time-Delay fuse
These fuses protect motors with high inrush of current on startup.
The delay prevents nuisance blowing while protecting the motor under sustained overload conditions.

Question 14

If the voltage of a machine is unknown, how should a multimeter be set so it doesn’t become damaged, when taking a measurement?

Answer 14

Start at the highest voltage setting and gradually decrease the setting value until a desired reading is shown

Question 15

What component of a motor is a fuse or breaker designed to emulate and protect?

Answer 15

Windings

Question 16

What device is used to measure the amperage of a high amperage motor?

Answer 16

Clamp-on Ammeter

Question 17

What multimeter setting is used to measure continuity of a solenoid coil?

Answer 17

Ohms

Question 18

How many ohms is 6.8 Megohms?

Answer 18

6,800,000 ohms
ohms >1000
K ohms - thousands
Megohms - millions

Question 19

Which of the following wire sizes would have the least resistance?

4, 1, 16 or 0

Answer 19

0

Larger the # means smaller wire.
Larger wire = less resistance

Question 20

What type of power supply is used in most industrial applications?

Answer 20

3-Phase AC
3-phase power can deliver more power with greater efficiency than single phase, by allowing larger motors to run on smaller wires with less line loss.

Question 21

What national organization ensures a minimum standard for installation and maintenance of electrical systems?

Answer 21

CSA
Canadian Standards Association

Question 22

True or False;
If the grease that is expelled from the vent port on an electric motor looks discoloured, continue to pump grease in until clean grease exits the vent port.

Answer 22

True

Question 23

What information on a motor nameplate designates the multiplier that can be applied to the horsepower to indicate the amount it can be overloaded?

Answer 23

SF - Service Factor
A multiplier that may be applied to the HP of a motor and indicates that the motor may be safely run at this loading at rated voltage and frequency

Question 24

True or False;
It is good practice to open disconnects with your left hand and to turn your body so your side is facing the switch door.

Answer 24

True; This stance protects you in case a fuse ruptures or arcs causing the doors to blow open. Use this stance when closing switches as well.

Question 25

Disconnects do what?

Answer 25

Disconnects the main power supply to the motor starter.
Disconnect = isolate power

Question 26

Voltmeters are connected in ___________ with the load.

Answer 26

Voltmeter = Parallel

Question 27

Ammeters are connected in _________

Answer 27

Ammeter = Series

Question 28

Always test ohms or connectivity with the power on or off?

Answer 28

Ohms = Power OFF

Question 29

P =
E =
I =
R =

Answer 29

P = Power in WATTS (rate at work work is done)
E = VOLTS (“pressure”)
I = AMPS (current flow)
R = OHMS (resistance)

Question 30

Conventional Flow runs?

Answer 30

Positive to Negative

Question 31

Electrons flow?

Answer 31

Negative to Positive

Question 32

The standard power line frequency used in North America is ___ cycles per second or __ hertz.

Answer 32

60 cycles per second
60 hertz
Alternating current(sine wave)