Single Motor Control/Pilot Devices and Symbols

Question 1

how are holding contacts connected with respect to the start button?

Answer 1

parallel

Question 2

How is the stop button connected with respect to the coil?

Answer 2

series

Question 3

What is the purpose of the holding contacts?

Answer 3

keep coil energized after push button is released

Question 4

what type of momentary contact pushbutton switch is used for stopping?

Answer 4

normally closed

Question 5

what type of momentary contact pushbutton switch is used for starting?

Answer 5

normally open

Question 6

how would the circuit operate if the stop and start buttons were interchanged?

Answer 6

the motor operates only when the normally open pushbutton is pressed. The holding contacts do not affect the circuit

Question 7

how must the start buttons be connected for multiple stations?

Answer 7

parallel

Question 8

how much stop buttons be connected for multiple stations?

Answer 8

series

Question 9

describe how a low voltage release works

Answer 9

Following a low voltage condition or loss of voltage, a magnetic contactor with low voltage release re-energizes the equipment when the voltage returns

Question 10

describe how low voltage protection works

Answer 10

following a low voltage condition or a loss of voltage, a magnetic contactor with low voltage protection does not re-energize the equipment until you manually restart it again

Question 11

automatic overload resets are designed for us with which type of circuit?

Answer 11

low voltage protection

Question 12

an exhaust fan for a warehouse most likely uses a low voltage _____ control circuit

Answer 12

release

Question 13

List five conditions to look for if a motor magnetic does not energize when the start button is pressed

Answer 13

no power to control, faulty stop button, faulty start button, burnt out coil, open overload contact

Question 14

a voltmeter is the preferred meter to use to troubleshoot a magnetic motor starter circuit.

True or false?

Answer 14

true

Question 15

Voltage across a normally closed device that is functioning properly in a live circuit is _____ volts

Answer 15

0V

Question 16

What are the two basic contact behaviors types used for pilot control devices?

Answer 16

maintained, momentary

Question 17

a start pushbutton switch used in parallel with holding contacts for a stop/start station is a ______ contact switch

Answer 17

momentary

Question 18

a standard single pole toggle switch is a _____ contact switch

Answer 18

maintained

Question 19

Do automatically operated pilot devices detect a change and convert this change to the opening or closing of a set of contacts?

Answer 19

Yes

Question 20

list four common types of pilot switching control devices

Answer 20

float, pressure, limit switch, temperature switch

Question 21

how is the tethered bulb float switch different than a level type switch?

Answer 21

The switch contacts are located in the float of a tethered bulb float switch. In the lever, they are located at the termination point of the lever

Question 22

what is the difference between a limit switch and a proximity switch?

Answer 22

With a limit, something must make contact with the object or material being sensed. Proximity switches do not need to make contact

Question 23

If you are asked to design a control circuit to empty a tank of liquid when the level reaches a certain point, the high-level limit is the ____ device and it is _____

Answer 23

start, NO