Deck 10: Jogging and Inching

Question 1

What is a hazard of push buttons?

Answer 1

Because push buttons employ a spring to return the contact to their normal position, if a person's finger slips off the jog button, it is possible for the spring to reestablish connection with the normally closed contacts before the holding contact has time to reopen. This would cause the motor to continue running instead of stopping. In some cases, this could become a significant safety hazard.

Question 2

Jogging can be accomplished using a double-acting push button.

Answer 2

True

Question 3

How can you reduce the amount of voltage applied to the motor during inching?

Answer 3

Transformers can be used to reduce the amount of voltage applied to the motor during inching, or reactors or resistors can be connected in series with the motor to reduce the current supplied by the power line.

Question 4

Figure 10-4


In the circuit shown in the accompanying figure, when the forward jog push button is pressed, the normally open section makes connection and provides power to ____________________.

Question 5

A selector switch is used to break the connection to the holding contacts.

Question 6

What is the difference between jogging and inching?

Question 7

Figure 10-5


In the accompanying figure, the START button acts as both the START and jog button for the circuit. A(n) ____________________ can be used to provide the same basic type control.

Question 8

You can obtain jogging control with the use of a selector switch.

Question 9

For a START-STOP push button control circuit that has been reconnected so that the START button is in parallel with both the STOP button and holding contact, how do you jog and run the motor?

Question 10

Inching control requires the use of a separate ____________________ because the power supplied to the motor must be separate from full line voltage.

Question 11

Figure 10-5


A single pole, single throw toggle switch provides jog or run control in the accompanying figure. If the switch is in the OFF position, the holding contacts can seal the circuit when the START button is released.

Question 12

Figure 10-3


Two circuits that employ a control relay to provide jogging are shown in the accompanying figure. In both these circuits the control relay provides the ____________________ contacts, not the M starter.

Question 13

Figure 10-4


The accompanying figure shows a jogging circuit for a forward-reverse control. What are normally closed F and R auxiliary contacts used for?

Question 14

The addition of a(n) ____________________ to the jog circuit eliminates the problem of the holding contacts making connection before the normally closed section of the jog push button makes connection.

Question 15

A control relay is used to provide jogging in one direction only.