Ground Fault Relays improve the safety of workers by minimizing the conditions that may lead to Arc-Flash incidents and maximizing the uptime of critical operations by avoiding nuisance tripping. Some relays are prone to nuisance tripping, which means they disconnect power and interrupt critical processes when no fault is present. This costs an enormous amount of time and man-hours trying to locate the problem. To avoid the nuisance tripping that occurs with conventional ground fault relays, maintenance workers tend to increase trip points well above sensitive levels. This practice, although very common, is extremely dangerous as the settings are dialed up so high that the relay will trip well after the damage has occurred.

Ground Fault Relays use an advanced filtering technology that allows for early detection of developing ground faults, without the nuisance tripping common in many competing products. The Littelfuse relays can be used in ungrounded, solidly grounded, and resistance grounded systems to protect critical, high-value equipment, and to meet National Electrical Code requirements for protection of ungrounded electrical systems (NEC 250.21B), solidly grounded systems (NEC 250.95), and resistance-grounded systems (NEC 250.36). The relays also have communications for remote monitoring.

Resistance-Grounded Systems are power systems with a resistor inserted between the system neutral and ground. This limits any ground-fault current to a predetermined, acceptable level. IEEE Std. 141-1993 states that there are no Arc-Flash Hazards associated with ground fault currents if the ground fault current is limited to 5A. Simply by using a Resistance-Grounded System, safety managers can lower the risk of Arc-Flash Incidents by 95 percent. However, if the resistor in the system fails, which usually goes undetected until a problem occurs, the system becomes ungrounded. To solve this problem, the Littelfuse Resistance Grounding Systems have an optional feature that continuously monitors the integrity of the resistor to ensure that the system is operating as intended.

Motor Protection Relays prevent expensive damage to motors caused by overloads, jams, phase loss or imbalance, as well as heat from non-electric sources, heavy startups or excessive operational cycles. Littelfuse Motor Protection Relays offer dynamic thermal curves, integrated protection, metering, and data logging functions that extend motor life and maximize process efficiency. A wide range of POWR-GARD Motor Protection Relays are available to protect any size motor. In addition, Littelfuse’s products are user friendly and easy to program.

Feeder Protection Relays protect feeder circuits from overcurrent, ground faults, phase loss or other detrimental conditions. POWR-GARD’s Feeder Protection Relays provide essential data for predictive and preventive maintenance, thereby extending the life of equipment, increasing its effectiveness, and improving safety.