Electrical Troubleshooting

Question 1

What is the sequence of operation?

Answer 1

Indicates the progression of operation for all devices on the elementary diagram.

Question 2

What is CR on an electrical diagram?

Answer 2

Control relay

Question 3

According to the NEC when should fuses be used?

Answer 3

Fuses should be installed on an ungrounded conductor and never installed in a grounded conductor.

Question 4

What is the meaning of a limit switch symbol with a downward pointing arrow next to it?

Answer 4

The same device appears on a lower line on the schematic.

Question 5

Which diagram shows the arrangement of components on a control panel?

Answer 5

A control panel layout

Question 6

Which diagram shows the actual location and routing of circuits?

Answer 6

They are shown on a wiring diagram

Question 7

What is shown on a lighting diagram?

Answer 7

Location of lights, lighting panels, and receptacles, and telephone wiring.

Question 8

Which diagram shows the power distribution wiring from input to transformer to output?

Answer 8

A riser diagram.

Question 9

What is not shown on a lighting diagram?

Answer 9

HVAC vents and ducts

Question 10

What is shown on a power installation drawing?

Answer 10

It only shows the power outlets.

Question 11

What is the most important step in troubleshooting?

Answer 11

To change one componant at a time.

Question 12

What kind of protection does a combination motor starter offer?

Answer 12

It offers overload and short circuit protection.

Circuit breaker and thermal disconnect

Question 13

What type protection does a start-stop device provide?

Answer 13

It only provides undervoltage release. The coil drops out when voltage becomes too weak to hold in the coil. When power is restored it automatically pulls back in. Not good for heavy machinery.

Question 14

What should you check if a motor stops for no reason?

Answer 14

First check the thermal overload relays

Question 15

What are the main causes of a magnetic coil burning up or short circuiting?

Answer 15

Overvoltage
Excessive current
Too frequent operation

Question 16

If you measure no voltage when the main contacts of the controller are closed the problem probably lies in the…..

Answer 16

Controller ( contacts not making up)

Question 17

Basic steps to follow upon a trouble call are?

Answer 17

Talk with the operator, ask about conditions and availability
press start, reset overload relay
troubleshoot from there

Question 18

Current ratings on contacts of control relays are usually 10A pilot duty. what types of loads to they have?

Answer 18

other relay coils, other contactors, or pilot lights

Question 19

When using an electronic time delay relay, both the time delay assembly and the relay coil are in series with……….

Answer 19

the line and the initiating contact

Question 20

Most reversing starters with low voltage remote pushbuttons are………

Answer 20

electrically interconnected

mechanically interlocked

Question 21

What is wired into the control circuit of a reversing motor for overtravel protection?

Answer 21

limit switches

Question 22

Operating a heavily loaded motor at reduced voltage can cause it to have high , causing overload tripping.

Answer 22

Slip

Question 23

A three phase induction motor can be reversed by?

Answer 23

Switching any two leads

Question 24

Two speed starters for squirrel cage motors are achieved by ………

Answer 24

changing the number of magnetic poles in the stator

Question 25

Deterioration of a selenium rectifier is can be indicated by .........

Answer 25

a reduction in output voltage an increase in input current sluggish operation of relays

Question 26

How should a good diode test with a resistance test?

Answer 26

Should be low ohms in one direction (free flowing under 20 ohms ) Very high in the other direction (blocking k ohms )

Question 27

Regular leakage of air in a pneamatic system is usually ..........

Answer 27

small enough to be ignored.

Question 28

What initiates the operation of an air piloted valve?

Answer 28

A surge of air. valve position maintained by pressure

Question 29

In regards to control logic a latched electrical relay is an example of a ........

Answer 29

bistable device

Question 30

If a motor runs with an open circuit, the speed and the winding temp .

Answer 30

speed decreases | temp increases

Question 31

What does oil accumulation around brushes and slip rings/commutator rings do?

Answer 31

mica insulation deteriorates causing arching increased brush wear forms a grinding surface

Question 32

What does mixing grades of brushes together due to the riding surface?

Answer 32

Creates uneven pressure and load distribution among the brushes.

Question 33

What determines the kind of lubricant you should use for a bearing?

Answer 33

operating temp

Question 34

What should be done before working on things that have been soaked with water?

Answer 34

Disconnect all power pull all fuses lock out disconnects and circuit breakers

Question 35

A pole phase group in a polyphase stator may become shorted. Usually indicated by high temp. in the faulted coil group.

Answer 35

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Question 36

When testing a 3 phase delta connected winding with a compass for a short what should you see when you break one conn. and apply dc to winding if everything is connected properly?

Answer 36

the compass will indicate alternating north and south poles around the stator frame. A Y connected test will result in a random deflection of the compass

Question 37

What are the 4 main causes of mechanical vibration?

Answer 37

Too much clearance at the bearings bent shaft imbalanced rotor misaligned couplings

Question 38

What are the common reasons a split phase motor makes excessive noise while operating?

Answer 38

loose rotor bars worn bearings worn centrifugal switch *NOT too little end play

Question 39

Planned preventative lighting includes......

Answer 39

group relamping periodic fixture and bulb cleaning troubleshooting

Question 40

What should be the first step in troubleshooting lighting?

Answer 40

Assure its seated properly and making good contact

Question 41

How long does NEMA recommend for overnight lamp seasoning?

Answer 41

12 hr full output before dimming

Question 42

All HID lamps require a startup and restrike before achieving full brightness

Answer 42

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Question 43

What is a "log"

Answer 43

a detailed description of all input commands, logic responses, outputs, and a machine motions

Question 44

All elementary diagrams must have all lines numbered consecutively.

Answer 44

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Question 45

One of the best ways to learn about new equipment is to troubleshoot it before, during and after installation

Answer 45

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Question 46

Before releasing new equip. after install be sure to check fuses and overloads for proper size, remove any leftover shipping material, actuate moving parts

Answer 46

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Question 47

As a means of identifying the motor, attach a permanent metal tag with he company's inventory number stamped on it .

Answer 47

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