HOG System Troubleshooting — Train Lighting & AC Coaches Notes

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This chapter covers real fault-diagnosis tables for HOG (Head-On-Generation) power supply issues — the actual indication lamps, switches, and fallback procedures staff use when HOG supply fails.

750V Supply Not Available

If the H7 indication lamp on the HOG panel isn't glowing: check whether input supply to converters is available in the loco, and whether the UIC coupler is properly connected.
If H1/H2 converter A/B 'on command light' and H5/H6 converter A/B 'output available light' aren't glowing: check that selector switches SW1 & SW2 on the HOG control panel are actually set for HOG operation, and confirm the ACB (Air Circuit Breaker) has been released.

Converter Output Tripping

Indicated by the faulty converter LED glowing at H3/H4. The converter automatically attempts to restart within 25 seconds after 3 consecutive trips. If it still doesn't start after this automatic reset, press the reset switch and hold it for a long time, then wait 3 minutes for the output-available lamp to glow. If the converter still won't turn on after that manual reset, staff must switch over to operating the EOG DG set instead, treating it as a genuine converter failure.

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Exam Focus — Two Different Time Values

Two specific, easily-confused time values: the automatic restart attempt happens within 25 SECONDS of 3 consecutive trips. The manual reset, by contrast, requires waiting 3 MINUTES for the output-available lamp after a long-press of the reset switch. Exam questions often swap these two values.

If the loco pilot reports a persistent 'Waiting for command' message on the converter display, and this is traced to the UIC coupler not being properly connected, the fix must wait until the next halt/station — lower the pantograph first, then check the UIC coupler connection.

Feeder Not Starting

No indication at all: check continuity of the safety loop first.
Check the primary and secondary fuses (K1/K2) of the 100/200VA transformer feeding the feeder contactor.
If the feeder's earth leakage/overload relay has tripped, reset the relay.
If none of these resolve it, fall back to operating the EOG DG set due to converter failure — the same fallback pattern used for converter tripping.

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Memory Aid — The Universal Fallback

Across almost every HOG fault scenario in the real manual, the ultimate fallback is the same: switch to operating the EOG DG set. HOG failures don't strand the train electrically — they just mean falling back to the older, power-car-based EOG generation the coach is still wired for.