A generator that runs on the commissioning day but fails during a real outage was installed, not engineered. These are the details that separate the two.
Diesel generators are simple machines with an unforgiving job: start reliably at the exact moment the mains fails, often after weeks of sitting idle. Most DG failures are not engine failures. They are installation failures.
1. The foundation and anti-vibration mounting
A DG foundation must carry the static weight and absorb dynamic vibration. Undersized foundations transmit vibration into the structure, loosen connections, and crack the plinth. We size the foundation mass against the set weight, isolate it where required, and install AVM pads matched to the operating frequency.
2. Ventilation and air change
An enclosed DG room needs air for combustion and, far more significantly, for radiator cooling. Insufficient air-change rates cause high coolant temperature and derating in summer — precisely when the load is highest. Inlet and outlet louvre areas are calculated, not eyeballed.
3. Exhaust routing
Excessive back pressure from long runs, too many bends or an undersized pipe costs power and increases exhaust temperature. Stack height must meet CPCB norms. Exhaust lagging protects people and reduces heat load in the room. Flexible bellows at the engine outlet prevent vibration transfer and thermal stress on the piping.
4. Fuel system
Day tank sizing, pipe routing with correct fall, a functioning vent, filters, isolation valves and leak testing. Fuel contamination and air ingress are common causes of a set that cranks but will not fire.
5. The AMF panel logic
This is where most "the DG did not start" complaints originate. Mains-failure sensing thresholds, start delay, crank cycles and rest intervals, changeover time, cool-down run and stop logic all need configuring for the site — not left at factory defaults. Then they need testing by actually killing the mains supply.
6. Earthing
Body earthing and neutral earthing are separate requirements with separate earth pits. Earth resistance is measured and recorded, not assumed. Neutral earthing decisions must be consistent with the site earthing philosophy so that protection operates correctly on the DG source as it does on mains.
7. Cable sizing and termination
Alternator-to-panel cables sized for full load with voltage drop within limits, properly glanded, with correct lug crimping and torque. Loose terminations are the leading cause of heating and eventual failure at the moment of highest current draw.
8. Battery and charger
The single most common cause of a no-start is a flat or sulphated battery. A functioning float charger, periodic battery health checks and correct electrolyte maintenance matter more than almost anything else in the installation.
9. Load bank testing
Commissioning on no-load or light load proves nothing. We test with a resistive load bank at steps up to full load, recording voltage, frequency, current balance, temperature and fuel consumption. This is also what prevents wet stacking on lightly loaded sets.
10. The handover file
Test records, panel schedule, single-line diagram, AMF settings, earth values, O&M manual and a maintenance schedule. Without it, the next engineer is guessing.
Maintenance beats installation quality over time
Even a perfect installation degrades without weekly no-load runs, monthly on-load runs, scheduled oil and filter changes and coolant checks. Reliability is a habit, not a commissioning certificate.
