devices operate by sensing a ground fault and opening the circuit very quickly. However, the GFCI devices used in residential and commercial applications are too sensitive to operate in industrial applications without nuisance tripping. That’s why UL 943C Class C and Class D standards cover GFCI devices for use with systems up to 600V that have leakage current higher than the 6 mA trip level of Class A GFCI devices.
Target applications of industrial GFCI devices include electrical cabinets supplying power to pumps, paint booths, washers, mixers, welding equipment, and any high voltage machinery subject to wet conditions or wash down cleaning. In addition, industrial GFCI devices can be mounted in movable enclosures for flexible use.
Electrical Shock Is a Leading Hazard
According to Tony Locker, P.E., product manager for Littelfuse Protection Relays, “the adoption of industrial GFCI devices is expected to grow because electric shock remains a major cause of workplace injury”. A recent IEEE white paper points out that although arc flash hazards are rightfully receiving a lot of attention, shock hazards should not be ignored as they are the cause of nearly all electrical fatalities and account for 61% of non-fatal electrical injuries.
Exclusive Features Enabled the Littelfuse Shock-Block™ GFCI to Pass Rigorous UL Tests
Industrial GFCI devices have a set 20mA trip level, which is set by the UL943 standard. Equipment ground fault protection devices have the same functionality as a GFCI but offer adjustable trip settings from 6mA to 30mA for added flexibility. Both models have voltage ratings range from 208 to 600 V and are rated at 100 A.
To pass rigorous UL test requirements, Littelfuse added several safety features which are not found on standard Class A GFCI devices including:
• Monitoring the integrity of the ground wire to ensure a return path for leakage current. If the wire is broken or becomes loose, the SB6100 device will signal an alarm and interrupt power. Without this feature, workers might wrongly assume they are protected even when the ground connection has failed.
• Even though UL requires a minimum short circuit current rating of 5,000 A, the SB6100 device is tested up to 50,000 A. This eliminates the need for adding external fuses for short-circuit protection.
• Performance requirements (Inverse time trip curve) specific for the application
In addition, the SB6100 Series goes beyond the UL standards by including built-in overcurrent protection supplied by Littelfuse Class T fuses. Because fusing is included, installation is easy and there are no extra costs. The interface has LEDs that indicate power and operational status, percentage leakage current, trip status, incorrect supply connection, and ground wire integrity status.
The new Littelfuse GFCI is available as an open-chassis unit that is UL-recognized for installation by an OEM, or as an enclosed unit having a NEMA-4X UL-listed enclosure.