GE 12HFA51A42H Auxiliary Protection Relay

Configured for high-speed multi-contact switching in protective relaying schemes, the GE 12HFA51A42H (12HFA51A42H Auxiliary Protection Relay) provides direct physical/electrical execution for tripping, interlocking, and status indication circuits. Suffix Breakdown & Model Matrix Code Position Option Designator Functional Description Base Family 12 Standard GE Drawout / Panel Mounted Auxiliary Relay Series Relay Type HFA High-Speed Multi-Contact Auxiliary Relay Platform Model Variation 51 Self-Reset Instantaneous Contact Mechanism Contact Configuration A Standard Form A / Form B Contact Combination Unit Voltage Rating 42 125 VAC Nominal Operating Coil Voltage Mounting / Cover H Surface / Flush Mounting with Standard Protective Cover Hardware Specifications Parameter Specification Model 12HFA51A42H Brand GE Origin USA Weight 6.59 lbs (2.99 kg) Dimensions Standard HFA Type hinged armature enclosure Operating Temp -20 to +55 deg C Power Consumption Coil burden driven (Standard HFA AC operating burden) Relay Type HFA Multi-Contact Auxiliary Relay Nominal Voltage 125 VAC Reset Mechanism Self-reset (Instantaneous) Contact Structure Heavy-duty multi-contact arrangement Deterministic Backplane & Contact Synchronization The relay utilizes a balanced hinged armature mechanism designed for ultra-fast contact pickup and simultaneous actuation across all output poles. Internal coil circuit isolation withstands high dielectric surge voltages, ensuring channel-to-channel isolation between auxiliary tripping outputs and breaker trip coils. High contact pressure minimizes bounce duration during heavy fault clearing, maintaining firmware flash compatibility and signal integrity across interconnected digital protection relays and power switchgear control buses. Frequently Asked Questions Q: What is the reset behavior of the 12HFA51A42H relay upon coil de-energization? A: The 12HFA51A42H is a self-reset relay. Upon removal of the 125 VAC control voltage, internal return springs instantly return all output contacts to their primary de-energized positions. Q: How does the physical construction support heavy-duty circuit breaker tripping loops? A: HFA relays feature silver-to-silver heavy-duty contact fingers capable of making and carrying high DC control currents required by power circuit breaker trip solenoids without contact welding. Field Installation Guidelines Panel Mounting: Securely mount the relay chassis vertically on a flat panel or switchgear rack to ensure proper armature movement and return spring tension. Coil Circuit Wiring: Connect 125 VAC operating power to designated coil terminals. Verify supply voltage stability to prevent coil hum or chatter under marginal voltage conditions. Grounding Connection: Ensure the metallic relay case and mounting frame are bonded to the switchgear ground bus using a dedicated ground conductor. Contact Inspection: Before energizing, manually inspect contact gap clearance and verify that no wire strands or foreign debris interfere with the hinged armature assembly.