Motor Jogging operation rotates the motor in slow increments. In jogging operation, the motor receives repeated starting and stopping commands in short bursts to perform slow movement.
The motor jogging operation is done in the equipment like barring drive and EOT cranes and winches. The motor operates at full power in jogging operation.
The inching operation is similar to jogging, but in the inching operation, the motor is operated at reduced voltage; thus, the motor draws reduced power.
Jogging and Inching
Definition of Jogging and Inching as Per NEMA
“The quickly repeated closure of a circuit to start a motor from rest for the purpose of accomplishing small movements of the driven machine.”
Though the terms jogging and inching are used interchangeably, they have a nuanced difference.
The term jog means moving slowly. The motor is started on short jabs at full voltage and takes full rated power for its operation. On the other hand, an inching operation is also done to perform slow movement. However, the motor is operated with short jabs of power at the reduced voltage.
The motor draws 6 to 7 times the current at the start, even at no load starting. The motor experiences heavy stress at the start. In jogging operation, the motor is started at full voltage at the loaded condition. Therefore, the motor experiences heavy electromechanical stress.
Therefore, the jogging operation must be done according to the motor’s duty cycle. The motor’s duty cycle specifies the recommended number of starts/min or starts/hour. Too many starts cause motor overheating and eventually motor insulation failure. The S4 duty motors are suitable for jogging and inching operations.
The starter and motor should be derated if jogging is performed more than the rated cycles.
Jogging Operation in AC motor
Repeated jogging more than the recommended starts produces heat in the induction motor, and excessive heat generation reduces the life of motor winding and causes insulation failure.
The jog control can be done through a simple jog circuit, i.e., push button and selector switch. When selected on jogging operation, the start button latch circuit gets disabled, and the motor starts by pressing the start push button. Also, lock the stop bush button during the jogging operation. The motor remains operative till the start button is pressed; once the button is released, the motor stops.
The crane and other applications using jogging/ inching operation are fed with a variable frequency drive. The VFD can be programmed for efficient jogging or inching operation.
Applications of Jogging a motor
The following are the applications of Jogging a motor.
- Machine Setup and Calibration: Jogging facilitates operators to precisely position machinery by precise control of the motor during setup or calibration.
- Testing and Troubleshooting: Jogging allows engineers and technicians to diagnose the problem in the machine by observing specific parts without running the motor continuously.
- Material Handling: In a material conveyor and handling system, jogging is used to move the conveyor slowly for inspection and adjustments.
- Indexing and Positioning: In CNC systems, jogging positions workpieces accurately.
- Feeding and Loading: Jogging is often used for incrementally feeding materials onto a production line in manufacturing processes. This ensures a steady and precise flow of materials.
- Manual Control Override: The operator can temporarily override the automated control system by using the jogging operation. This type of requirement arises for emergency stops, repositioning, or fine-tuning during automated processes.
- Training and Education: Jogging is used to educate the operators and technicians for safe and effective operation and control of the motor.
- Print and Inspection: Jogging is used in printing and packaging machinery to align print heads, adjust paper or packaging material, and inspect the quality of printed products.
- Entertainment and Amusement Ride: Jogging operation is also used for precise control of ride movement and positioning to ensure the safety and enjoyment of passengers in applications like amusement park rides
- Elevators and Lifts: To ensure passengers’ safe entry and exit in elevators and lifts, jogging allows controlled movement and precise floor leveling.
- Robotics: Jogging is used in robotic systems for tasks such as pick-and-place operations.
- Laboratory Equipment: Jogging is used to move lab equipment, adjust microscope stages, and position sensors and instruments accurately In scientific and research settings