Generator Protection and Control System Functions

Generator Protection & Control⚡️ 

 1. Electrical Protection Layer 🛡️

 • This is the main nervous system of a DG set.

 • 87G Differential gives ultra-fast internal winding fault clearance.

 • 50/51 & 50N/51N cover external short circuits on phase and earth.

 • 46 Negative Sequence protects rotor from heating due to load unbalance.

 • 27/59 Voltage & 81O/U Frequency keep the machine inside AVR & governor limits.

 • 32 Reverse Power stops motoring action when the prime mover fails.

 • 40 Loss of Excitation avoids pole slip in synchronous generators.

 • 24 V/Hz prevents core over-fluxing during start or AVR malfunction.

 • 50BF + 86 Lockout ensure dependable isolation even if breaker refuses to trip.

 2. Mechanical / Engine Interface (via GCU) 🔧

 • A generator is half electrical, half engine.

 • 63 oil pressure, 26/38 temperature, 71 level watch prime mover health.

 • 51LR locked rotor limits starting stress.

 • 66 starts/hr respects manufacturer duty cycle.

 • These signals combine with electrical trips for total machine safety.

 3. Synchronizing & Grid Parallel 🌐

 • Parallel operation needs system-level intelligence.

 • 25 Sync Check matches voltage, frequency & phase before closing.

 • 78 Pole Slip detects loss of synchronism.

 • 81R ROCOF & 59N meet grid code requirements.

 • 67/67N Directional identifies fault direction with multiple sources.

 • 32R controls unwanted reactive power flow.

 4. Grounding & 100% Stator Coverage ⚙️

 • Normal OC cannot see faults near neutral.

 • 64G / 59G detect neutral displacement.

 • 87N/87GN REF provide sensitive internal earth fault protection.

 • 50G acts as instantaneous backup for severe faults.

 5. Control & Supervision 👁️

 • Protection must be supervised continuously.

 • 95 TCS proves trip coil integrity.

 • 30/74 annunciation gives operator visibility.

 • 52 breaker & 43 selector integrate with AMF/SCADA.

 • 90 AVR interface links excitation with protection logic.