ABB REK510-AA REK510 Current Injection Device

The ABB REK 510-AA is a specialized, high-reliability current injection device utilized within medium-voltage generator protection and control systems. Acting as a dedicated Current Supply Unit, its primary function is to provide comprehensive rotor earth-fault protection by proactively detecting single insulation breakdowns within the excitation circuits of large synchronous motors and power generators. Detecting this initial single insulation fault is critical to avoiding secondary grounding faults that induce dangerous magnetic unbalance and severe rotor damage.

Operating by establishing a baseline 100 VAC secondary voltage matrix using high-quality coupling capacitors, the REK 510-AA injects a small, controlled AC charging current to ground. When insulation degrades, the ground current shifts dynamically up to a maximum short-circuit cap of 130 mA. Thanks to its integrated internal 1:10 amplification transformer, it routes clear, readable signals directly to definite-time overcurrent or earth-fault relays for immediate tripping action. Revision D components optimize power efficiency by capping consumption at ≤ 15W, alongside added internal damping chokes to isolate against field excitation harmonics.