Overcurrent Relay

Arc fault protection is a relatively new technique employed for the fast clearance of arcing faults on Busbars & within metal clad switchgear & associated cable boxes. The arc is detected using an optical sensor & the signal input to a protection device which also monitors the load current on the system. Conventional current based protection techniques are at times challenged by the nature of arcing faults, and can result in slow protection clearance times. Slow protection clearance times increase the risk to nearby personnel and increase the degree of damage to plant and equipment. By employing an optical detection technique, Arc Fault Protection results in fast clearance of arcing faults.

When an arc fault start current is coincident with a signal from the optical sensor a trip command is output. An Arc trip only signal can be achieved within 10ms which can be considerably faster than that provided by a traditional IDMT overcurrent relay. This is because the onset of an arcing fault can occur at relatively low fault currents. Arguably the greatest risk of arc fault damage exists at the CB cable termination & in the CB chamber itself due to the slow clearance times of the IDMT feeder protection.

The ReyArc range of protection devices provide multiple arc fault protection schemes depending on your protection system requirements:

ReyArc Arc Protection range:

• 7XG3120 Arc Fault Monitor Detects Arc faults independently & in parallel with an overcurrent check relay.
• 7XG3123 ARC Fault Module - Designed to connect one or two optical arc fault sensors to a protection relay status input.
• 7XG3124 IEC61850 Arc Fault Monitor – Arc Fault detection using IEC-61850
• 7XG3126 Arc Fault Monitor with Integrated Three Phase Current Check
• 7XG3130 Optical ARC Fault Senso