Motor protection is a very crucial part of electrical induction motor protection. Most industries use induction motors, and protecting them and ensuring their functionality is vital since production, delivery and revenue generation is highly dependent on these motors. The motor outage may lead to safety issues, delay in production, and a higher rate of inefficiency. A damaged motor may also result in spreading the issue to the grid. Hence, a well-founded motor protection plan is of utmost importance.
Motor protection plans require several factors to be considered. Some of them are:
- Horsepower rating and type of the motor.
- Essential features of the motor like the method of grounding, phases, voltage, and the mentioned short-circuit current.
- Mechanical specifications like torque and vibration.
- Surrounding of the motor and the linked switching device.
- Hot and cold authorised locked-rotor time and approved accelerating time.
- Study of the time versus current graph while powering the motor.
- The repetition of starting the motor.
There are diverse categories of protection for a motor. Some of them are discussed below:
Overload Protection
This kind of protection is offered against mechanical overload situations. Mechanical overload situations often take place in a motor due to different factors when the motor is operating. Overload conditions can cause a high temperature in the motor, which will ultimately harm the motor. By opting for motor protection against overload conditions, the motor can be delinked from the primary power source. If there is no protection, an uncontrolled temperature rise may end up causing hazardous fires and other accidents.
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Overcurrent Protection
At times, an excess amount of current travels through a motor. This causes the motor protection unit to trip. Devices like circuit breakers and fuses are used for protecting such cases. Overcurrent protection ensures protection from electric shock, saves the control unit of the motor, the motor from the damaging effects of high currents, and the conductors of the motor circuits.
Low Voltage Protection
This kind of protection saves the motor when the voltage level drops below the rated level of the motor. In a crisis period, low voltage protection allows the motor to be disconnected from the voltage source. The function of the motor restarts as soon as the voltage level is back to the recommended one. While some motors may require manual resetting, most others reset themselves automatically with the help of specific algorithms.
Phase Failure Protection
Sometimes a phase may fail when the motor is still operating. Phase failure protection is usually used in three-phase motors. Like other protection methods, the motor is disconnected from the primary power source to ensure the health of the motor. At times, the affected motor may continue operating even when a phase fails. This is because when one phase fails, the other two phases supply more power to the motor. This situation may result in the motor catching fire. Hence, phase failure protection is significant.
Phase Reversal Protection
Phase reversal is a dangerous situation that occurs when two connections of a three connections motor get reversed. This results in the motor operating in opposite directing. As soon as the protection mechanism identifies the reversed movement, it disconnects the motor from the main supply.
Ground Fault Protection
This protection offers safety to a motor from various short circuits that result due to ground faults. Like other protections, this one also disconnects the motor from the power source as soon as the defect is identified.
Schneider Electric India offers diverse options for motor protection. Visit their website today and learn more about them. From straightforward or essential security to cutting edge Motor Protection applications, they utilize committed capacities and correspondence like IEC 61850 that empower you to oversee engines all the more successfully and save time.
