Manual AC Motor starters

Question 1

What is a Motor?

Answer 1

Motor is an electrical machine that converts electrical energy into mechanical energy.

Question 2

What are the two types of motor starters?

Answer 2

1. manual
2. Automatic (magnetic)

Question 3

What is a motor starter?

Answer 3

A motor starter is a mechanism used to safely start and stop the motor, and also to provide some running protection for the motor.

Question 4

What is toggle switch?

Answer 4

The toggle switch starter is a snap-action switch, giving simple on-off control.

Question 5

What is a drum switch? What is the purpose of using it?

Answer 5

Drum switch is a rotary-action selector switch. Used to manually control speed and to change directions of motors.

Question 6

Drum switch provides overload protection. True or False.

Answer 6

False. Drum switch does
not provide overload protection.

Question 7

What are the two types of thermal overload protection?

Answer 7

1. Melting alloy relay
2. Bimetallic strip overload relay

Question 8

When overload occurs, ______________, then reset the contacts

Answer 8

allow a cooling-down period

Question 9

What is the maximum HP rating for toggle switch?

Answer 9

1 HP

Question 10

What is the maximum HP rating for push button?

Answer 10

5 HP

Question 11

What is control relay?

Answer 11

A magnetic devices that are used to remotely switch loads. They are functionally identical to a magnetic motor starter, save that control relays lack horsepower-rated contacts and built-in overload protection.

Question 12

What is the difference between low-voltage protection and low-voltage release?

Answer 12

Low-voltage protection- can automatically restart when power is restored to its normal level.

Low-voltage release- must be manually reset when power is restored.

Question 13

How does thermal overload relays operate?

Answer 13

connecting a heater in series with the motor. The amount of heat produced is dependent on motor current

Question 14

The two major types of overload relays:

Answer 14

Thermal and Magnetic

Question 15

How does magnetic overload relays operate?

Answer 15

Operates by sensing the strength of the magnetic field produced by the current flowing to the motor.

Question 16

How does dashpot relays operate?

Question 17

Overload Relay are designed to open the circuit when the current becomes ______ to _______ of the motor full load current.

Answer 17

115% to 125%

Question 18

The three certain properties that all overload relays must possess in order to protect a motor are:

Answer 18

1. They must have some means of sensing motor current.
2. They must have some type of time delay.
3. They are divided into two separate sections: the current sensing section and the contact section.

Question 19

What is another term for inrush current?

Answer 19

Locked rotor current

Question 20

Overload relays are divided into two sections. What are the two sections?

Answer 20

1. Current Sensing section
2. Contact section

Question 21

What are the two section that Dual-Element Fuses contain and how do each of them function?

Answer 21

Fuse link- designed to open quickly under a large amount of excessive current which protect against direct grounds and short circuit.

Solder link- Highly controlled alloy designed to melt at certain temperature which protects the motor.

Question 22

Thermal overload relay can be divided into two types are:

Answer 22

1. solder melting type or solder pot
2. bimetallic strip type

Question 23

The heater is connected in _______ with the motor

Answer 23

series

Question 24

Thermal Overload Relay is not sensitive to ambient temperature. True or False?

Answer 24

False. They trip faster when located in a warm area than they do in a cool area.

Question 25

What is Bimetal Strip Overload Relay?

Answer 25

Bimetal Strip overload relay is a second type of thermal overload relay. When the Bimetal strip is heated excessively, the strip bends or warp which causes the contact to open to protect the motor.

Question 26

What the major difference between magnetic type and thermal type overload relay?

Answer 26

Magnetic overload relay is NOT sensitive to ambient temperature.
Thermal is sensitive to ambient temperature.

Question 27

Magnetic overload relays can be divided into two major types:

Answer 27

electronic and dashpot

Question 28

What are the six different functions provided by motor controllers

Answer 28

1. Starting
2. Stopping
3. Jogging or inching
4. Speed Control
5. Motor and Control Protection
6. Surge Protection

Question 29

what is the difference between over and overcurrent?

Question 30

What is the difference between low voltage protection and low voltage release?

Question 31

What is meant by the term “ramping”?

Answer 31

The motor to start at a low speed and accelerate to full speed over some period of time.

Question 32

Pushbutton motor starters are used for single-phase motors that are typically rated at a maximum__________ at _____.

Answer 32

5HP. 230V

Question 33

Most toggle-switch starters are rated at maximum ______ at __________.

Answer 33

1HP, 230V

Question 34

The __________ is a rotary-action selector switch that is commonly used to manually control speed and to change the directions of motors.

Answer 34

Drum Switch

Question 35

Pilot lights must _______ be installed in series with motor starters; the motor starter might not have enough voltage to pull in, and if the filament in the pilot light burns out, it will create an open in series with the rest of the circuit.

Answer 35

NEVER