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procedures > S2.OP-ST.DG-0001 — Emergency Diesel Generator Surveillance Test

S2.OP-ST.DG-0001 — Emergency Diesel Generator Surveillance Test

⚠️ DRAFT

S2.OP-ST.DG-0001 — Emergency Diesel Generator Surveillance Test

Purpose

Provides direction for performing monthly and 18-month surveillance testing on emergency diesel generators, including load testing with synchronization to the grid.

Key Precautions & Limitations

Exam — 2023 Q89
P&L 2.1.6: Only one DG per Unit may be synchronized to the grid at a time. This prohibition minimizes any potential common failure resulting from undetected interdependence among diesel generator units (Reg Guide 1.108, Section C.2.b). For common mode failure testing across both units, the most expeditious compliant method is one EDG per unit simultaneously (e.g., 1B and 2B at the same time). Running multiple EDGs on the same unit simultaneously violates this P&L, even during urgent common mode failure testing.
Exam — 2022 Q50
Step 4.3.8.1.c Caution: After closing the generator output breaker, immediately raise generator load to ≥ 500 KW to prevent tripping the output breaker on reverse power. The concern at low load is reverse power trip, not exhaust fire. Oil accumulation in the exhaust system from low load operation is a separate P&L concern (P&L 2.19) from S1.OP-SO.DG-0001 regarding gradual loading to avoid exhaust fire.
Exam — 2022 Q89
TS 3.8.1.1 common mode failure: when an EDG fails due to a component (e.g., K1C relay) and the same component is installed in other EDGs, a common mode failure exists or cannot be ruled out. Action b.3 requires performing an operability run within 24 hours on the remaining operable EDGs. Action b.4 requires restoring the inoperable EDG within 72 hours. Common mode failure does not automatically make all EDGs inoperable — TS 3.0.3 does NOT apply because action "e" exists for two or more inoperable diesels.
Exam — 2018 Q42
EDG load test key values: to prevent tripping the DG Breaker on reverse power, generator load must be IMMEDIATELY raised to greater than a minimum of 500 KW after the breaker is closed. The 2A EDG may NOT exceed its 2600 KW Continuous Load Rating during the load test. P&L also states the EDG is rated to 2750 KW for 2000 hours (2681 KW Local). When UNLOADING, maintain generator load > 200 KW until breaker is opened. Trap: 500 KW is for LOADING (breaker closure), 200 KW is for UNLOADING (before breaker opening). 2600 KW is Continuous rating, 2750 KW is 2000-hour rating — candidates confuse these.

Surveillance Test Steps

Exam — 2020 Q48
Step 5.3.11: When EDG is paralleled to the bus for load testing, Voltage Control Switch adjusts KVAR (reactive) load. To raise KVAR OUT from 1200 to 1400-1500 KVAR OUT, use Raise on the Voltage Control Switch. Speed Control Switch adjusts KW (real) load, NOT reactive load. Speed control and voltage control functions are easily confused when a generator is paralleled to the grid.

Connections