Diesel Generator (DG) sets (DG set)

A diesel generator (DG) set is a packaged power-generation unit in which a diesel engine drives an alternator that converts mechanical rotation into electricity. It is the standard backup power source in Indian industry, used to keep operations running through grid outages and to ride through voltage fluctuations that would otherwise trip or damage sensitive equipment. For continuous-process plants — pyrolysis reactors, extruders, blowers — even a short power cut can spoil a batch or force an unsafe shutdown, so reliable backup is not optional.

DG sets are tightly regulated on two fronts. On noise, CPCB norms require DG sets to be supplied with an integral acoustic enclosure at the manufacturing stage, delivering a minimum insertion loss of 25 dB(A), with the requirement applying to sets manufactured on or after 1 January 2005. On emissions, DG sets must meet the applicable CPCB emission standards (the staged norms for gensets) and observe stack height requirements so exhaust disperses properly. Both are checked by SPCBs and are typically conditions of the plant's consent to operate.

Sizing and fuel cost are the commercial issues. A DG set must be rated for the plant's actual peak load with a margin, but an oversized set runs inefficiently at low load and wastes diesel, while an undersized one cannot carry the plant. Diesel is an expensive fuel per unit of electricity compared with grid power, so a DG set is a backup, not a base-load source — running primarily on a DG set usually wrecks the operating cost. Where outages are frequent, the better answer is often improving the grid connection or adding solar plus storage rather than running the genset more.

For an Indian entrepreneur the guidance is to buy a CPCB-compliant DG set with a factory-fitted acoustic enclosure (not a retrofit), confirm its insertion-loss and emission certification before installation, site it away from the boundary to help meet ambient noise limits, and provide the required exhaust stack height. Size it to peak load with a sensible margin, and treat its run-hours as a cost to minimise — design the operation to lean on grid power and use the DG set as genuine backup.