A look ahead ground fault relay is a solution that is designed with a 120 VAC under voltage and shunt trip breakers on the circuits. These systems are limited to just 25 amps or less with ground fault current and the system can be factory adjusted to trip at 6 amps through ground fault with a current transformer.
These types of relays use a breaker for indication and tripping. When a ground fault system occurs in the breaker, it will be tripped and reset manually. A resistor in the series with the breaker will not be required and the ground fault is also not required with these relays.
The lookahead circuit can verify that there is no fault present and the contractor or circuit breaker can be appropriately closed when required. The molded case circuit breaker will require at least 30 seconds for this to take place, but this solution can prevent serious disasters in a mining site. The relay can be scalable to 180 seconds in applications where loads are required for greater dissipation back to the EMF and the motor circuit. These designs come with two main modes of operation including the CT test function. The look ahead mode can continually test the hold voltage circuit for motor ground faults and cables and the ground fault mode will monitor the signal and convert it to an ampere reading for programmed results.
Signals in these devices are connected through a contactor input which has terminals set in the rear of the look ahead relay. The 120 volt ac signal can be present along the contactor input and the circuit breaker gets closed in the time display. The illuminating yellow or red display will test the function and showcase look ahead results. As the LED delay is extinguished, the look ahead relay gets set to the ground fault mode.
If you are seeking quality relays for improving safety throughout your mining site, consider these options in ground fault relays. Contact us today if you are interested in installing this technology throughout your mining site.
This post was written by Justin Tidd, Director at Becker/SMC. For nearly a half a century, Becker Mining has been at the forefront of safety, producing the best ground fault relay in the industry. Becker/SMC is the industry’s leader in increasingly more sophisticated electrical control systems. Most of the major innovations, design features and specialized electrical components have been developed by Becker/SMC.