JOG MOTOR CONTROL

Definition

Jogging is defined as the brief closure  of a motor circuit to energize a motor for a short period of time and perform a small movement of driven machine.

Figure below illustrates the schematic diagram of the control and power of a Jog Motor Control.

A motor is jogged for the following reasons: to align and space machine parts; to position a tool accurately; to thread cloth, paper, or sheet steel; and to provide small controlled movement.

Schematic diagram of the control and power circuits  of the “Jog Motor Control“

 

Control Operation

The start and stop operation of the jog motor control is the same as the start and stop operation of the across line magnetic starter. In a jog motor control, a dual push button with one normally motor control open and one normally close contacts is inserted in between the normal STOP and START push button of the across the line magnetic starter.

Referring to figure above, when the jog push button is pressed, current will flow from line L1, normally closed O.L. contacts (95-96), STOP push button, Jog push button contact (3-4) ,START push button contact (3-4), contactor C (A-B) to line L2. The contactor C (A-B) will be energize to cause the motor M to run. Motor M will continue running as long as the jog push button is being pressed.

At this condition the RUN pilot lamp is energize while the IDLE pilot is de-energize because of the opening of contact C (11-12).Once the Jog push button is depressed (released) contactor C is de-energized. The motor M will stop contact C (11-12) will close and the IDLE lamp is energized .Contact C (13-14) will open to de-energized the RUN pilot lamp. Even if the jog push button closes its contacts (1-2), the contactor C can no longer energized since contact C (13-14) is already open.