Heat trace is a type of electrical heating that is used for a wide variety of applications from de-icing roofs and walkways, to process control in industrial facilities. The de-icing or anti-freezing products are often called heat tapes and are of the resistance type. While resistive types are common, skin-effect and induction systems are also in use. Industrial heat-trace cables are typically run along pipes and around vessels to maintain temperature and can involve many circuits with a complex control system—these require equally sophisticated ground-fault protection.
The National Electrical Code, in Section 427.22, requires heat trace circuits and heating panels to have ground-fault protection of equipment (GFPE), with specific exceptions, which is described as from 6 to 50 mA. In industrial and residential applications, 30 mA is often used as the default value. The Canadian Electrical Code, in Rule 62-116, with specific exceptions, requires ground-fault protection for electric heat tracers and heating panels. This is described as a setting low enough to allow normal operation.
Because heat trace is an electrical resistance, current is inherently limited by the heating element. When the electrical insulation of a heat trace cable is damaged, the heating element can come into contact with a grounded object, such as a pipe or vessel—which results in a ground fault. The electrical contact energizes the pipe or vessel, but the fault current can be small (limited by the resistance of the heating element plus the resistance of the ground fault), requiring sensitive detection and protection (tripping) at the low-mA level.
The RCM410R is an 18-mm wide DIN-rail mount advanced low-cost ground-fault relay that, paired with a Bender ground-fault current transformer and connected to an interrupter (circuit breaker or contactor), provides ground-fault protection as low as 10 mA while communicating to an industrial data network. Pickup and delay settings are on-device, with Modbus, or with near-field communications. Using NFC means any number of units can be programmed while not powered. Imagine configuring 40, 60, 80 units for a large panel with a simple wave of your smart device—saving hours of installation and commissioning cost.