Motor control circuits
Induction Motor Jog (Inching) Circuit
What is jog (inching) operation?
In jog or inching operation the motor runs only while the button is held down. As soon as the button is released, the contactor de-energizes and the motor stops; it does not keep running on its own.
Where is it used?
It is used to lift loads little by little with cranes and hoists, to position parts on machine tools, to adjust conveyor systems and to turn a shaft step by step during maintenance. It is preferred wherever the operator follows the movement by eye and uncontrolled motion would be dangerous.
Power circuit and control circuit
The power circuit is the same as direct-on-line starting: circuit breaker, contactor, overload relay and motor. The control circuit is as simple as it gets; the start button energizes the contactor coil directly and there is no seal-in. That makes this circuit a good starting point for understanding control logic before moving to the seal-in circuit.
What to watch out for
Starting a motor very often for short periods heats it up because of the starting currents. Where jogging is heavy, the motor and contactor are chosen for this duty.
Parts used
- Motor 3~
- M1
Run it in the simulator.
This circuit is ready in the CoilPath library. Open it, press the buttons and follow the current. It also comes with a wiring view and a panel layout.
Related circuits
- Seal-in Circuit (Continuous Running of an Induction Motor)
- Seal-in Circuit (Continuous Running of an Induction Motor with a Relay)
- Jog Button with Momentary Running and Seal-in Cancel Circuit
- Seal-in Circuit with Start–Stop Control from Three Locations
- Forward–Reverse Direct-On-Line Starting Circuit
- Sequential Induction Motor Starting with Timer Relays