Protecting Remotely Located Motors: Application Issues and Solutions to the Technical Challenges

The basic goals of motor protection are allowing the motor to operate as close to thermal limits as possible and isolating the motor when actual failures occur. The basic principles for performing this protection are well known. In most installations, the motor is located close to the protective relay and interrupting device, be it a contactor, starter, or circuit breaker. However, the motor may sometimes be located remotely from the protective relay due to the needs of the physical process or due to operational safety requirements. Distances of 1,0002,000 ft between the motor location and the protective relay are common. This large distance does not change the motor protection used, but it does require careful application engineering to ensure reliable protection performance.