Challenge: The National Electric Code requires that all (with few exceptions) electric heating sources be protected against faults to ground. Combinations of electrical heating systems and moisture can present a challenge in ground fault protection. Insulation systems of heating elements can degrade over time in the face of wide temperature variations, constant expansion and contraction, and wet conditions. In heating applications it is important to balance protecting personnel while minimizing nuisance trips. Disconnecting the circuit is the best protection in both instances, and the faster the circuit can be de-energized the safer the installation.
Typical Electric Heating Applications:
- Heat Trace Cable
- Snow Melt Mats
- Fuel Preheaters
- Plastic Injection Molding
- Finish Curing
- Water Heating
Solution: NK Technologies has a wide assortment of ground fault relays to achieve an optimal solution based on the application needs. AG series ground fault relays are ideal for lower current applications where a quick disconnect is desired. If there is any current over five milliamps f lowing to ground, the sensor can actuate a contact to close a shunt trip breaker solenoid, or in applications where turning off the offending circuit would create a major problem, the contact can be used to alarm an operator or controller. The AGL and AG-LC series relays makes it possible to monitor conductors carrying over 200 amps (or even larger circuits) for applications with larger heating requirements. NK Technologies also manufactures ground fault sensors designed to produce an analog signal directly proportional to the fault current. This output can to identify areas where insulation is failing, allowing the user to take corrective measures before equipment is damaged. This range of product allows the designer to optimize the solution that best fits the application requirements.