In short. Mining and quarry power is defined by large motors, harsh air and distance. Crushers, conveyors, dewatering pumps and ventilation fans impose heavy starting loads, dust and heat erode the generator’s rating, and a breakdown hours from the nearest workshop stops production for a shift or longer. Size for the real start sequence, derate honestly for the environment, specify prime-rated sets with spare capacity, and plan fuel, filtration and service access as part of the power system.
Deciding the duty before the capacity
The first question at a mine or quarry is not how many kVA, but what role the generator plays. At a granite quarry near Hyderabad with a DISCOM feed, the generator is standby for the crusher line and may run a few hundred hours a year. At a sand mine or an exploration camp with no grid, it is the only source and runs 4,000 hours or more. At a limestone quarry feeding a cement plant, it may be prime power for dewatering and lighting while the crusher runs on grid. These three cases call for different ISO 8528-1 ratings, different cooling and filtration, and different fuel arrangements. Specifying a standby-rated set for off-grid duty is the most expensive mistake in this sector. The prime power page explains the rating definitions.
Motor starting at the crusher line
A quarry crusher line is a sequence of motors: primary jaw crusher, cone crusher, vibrating screens, conveyors and a dust suppression pump. The largest single motor at a mid-size quarry is typically the primary crusher at 75 to 160 kW, often started direct-on-line because the plant was designed for a stiff grid supply. On a generator, the start of a 110 kW crusher motor at six times full-load current demands around 900 kVA for a second or two, far more than the running load of the whole plant.
Generator kVA for starting ≈ Starting kVA of largest motor ÷ allowable step fraction
The allowable step fraction comes from the alternator’s transient data: a typical alternator accepts a sudden step of roughly 0.3 to 0.5 of its rating in kVA for a 20 per cent transient dip, so the set must be two to three times the motor’s starting kVA, confirmed against the manufacturer’s motor-starting curves. For the 110 kW crusher started direct-on-line this points to a set of 500 to 750 kVA depending on the alternator (illustrative), unless the start is softened. Converting the crusher to a soft starter, or sequencing the line so no two large motors start together, usually brings the set back to the size the generator sizing guide would predict from running load. The large-motor starting guide gives the full method, including the effect of crusher inertia on start time.
| Starting method | Starting current (× FLC) | Effect on generator size | Suits |
|---|---|---|---|
| Direct-on-line | 6 to 7 | Largest set required | Pumps and motors under 30 kW |
| Star-delta | 2 to 2.5 | Set reduced by about half | Conveyors and screens with low starting torque |
| Soft starter | 2.5 to 4, adjustable | Set reduced, start time longer | Crushers, large pumps |
| Variable-frequency drive | 1 to 1.5 | Smallest set, but harmonics added | Conveyors, fans, ventilation |
Dust, heat and altitude derating
A generator at a quarry lives in the worst air on site. Stone dust loads the air filter in days, blankets the radiator core and settles inside the alternator, where it holds moisture and lowers insulation resistance. Ambient inside a steel canopy in the Telangana summer can exceed 50 degrees Celsius when the shade temperature is 42. Engine manufacturers typically derate output above 40 degrees Celsius and above 1,000 metres altitude; the exact figures must be read from the engine data sheet, but a combined derate of 10 to 15 per cent is not unusual at a hot, dusty site on the Deccan plateau. Specify two-stage air cleaners with pre-cleaners and restriction indicators, a radiator with wider fin spacing or a remote radiator in clean air, and an alternator with a higher IP rating and filtered inlet. The ambient derating guide explains how to apply the corrections.
Redundancy and the distance to recovery
At an urban factory a generator breakdown is a two-hour wait. At a mine four hours from Hyderabad, it is a lost shift at best. Judge redundancy against recovery time, not failure rate. For an off-grid operation the common pattern is two or three prime-rated sets in parallel, sized so the essential loads run with one set out, with a controller that starts and stops sets as demand changes. This also solves the low-load problem: at night one set carries the camp and pumps while the others rest. The generator paralleling page covers switchgear and controls, and the mining microgrid page describes adding solar and battery storage at long-duration sites.
Spares and service on site
Carry on site the items that fail between visits: filters for two service intervals, fan belts, a set of batteries, coolant and radiator hoses. Train one operator to perform daily checks and read the controller alarm log, and agree service intervals in hours rather than months, because a prime-rated set at 20 hours a day reaches a 250-hour service in under two weeks.
Fuel logistics and storage
A 500 kVA set at 70 per cent load consumes roughly 75 to 85 litres an hour, around 1,800 litres a day on continuous duty (illustrative). Fuel storage at a remote mine must cover the delivery interval with a margin for monsoon road closures, and the bulk tank must keep water and sediment out of the engine: a settling leg, a water drain, a transfer pump with water separator, and a day tank drawing from above the tank floor. Diesel stored for months in a hot climate grows microbial sludge, so periodic sampling and fuel polishing belong in the operating plan. The fuel tank sizing guide covers autonomy calculations and the Petroleum Rules limits above which a PESO licence is required.
Regulatory and safety points specific to mines
Electrical installations at mines in India fall under the Directorate General of Mines Safety in addition to the CEA regulations, so earthing, protection and isolation arrangements should be documented for DGMS inspection. New diesel sets up to 800 kW must meet CPCB IV+ emission norms. Where blasting is done, the generator and fuel store must sit outside the blast exclusion zone and be protected from fly rock.
Common mistakes
- Buying a standby-rated set for an off-grid mine because it is cheaper per kVA. The engine runs far beyond its design hours and fails early, usually in the hottest month.
- Sizing the generator on the running load of the crusher line without checking the primary crusher start. The set holds the plant once running but cannot restart it after a trip.
- Using a standard single-stage air cleaner at a dusty site. Dust reaches the cylinders, oil consumption rises and the turbocharger wears within a year.
- Treating fuel delivery as someone else’s problem. A monsoon road closure empties the tank and the mine stops for days.
What to send us
Send the motor list for the crusher line and pumps with kW, starting method and the sequence in which they start, the daily operating hours and whether grid supply exists at the site. Add photographs of the proposed generator location, the site altitude and the distance from Hyderabad or the nearest town for service planning. If an existing set is struggling, include its nameplate and the controller alarm history. Send your mine or quarry power requirement.
Questions engineers ask
What generator size does a stone crusher need?
Size it from the largest motor start, not the plant total. A 100 to 110 kW primary crusher started direct-on-line may need a 500 to 750 kVA set to hold voltage, while the same crusher on a soft starter can often run from 320 to 400 kVA. The alternator’s transient data decides the final figure.
Prime or standby rating for a quarry generator?
If the set runs more than about 500 hours a year or is the only supply, specify prime rating. Standby rating is only for sets that back up a grid supply during outages. Running a standby-rated set as prime shortens engine life and usually voids the warranty.
How much do dust and heat reduce generator output?
At a hot, dusty quarry the combined effect of ambient above 40 degrees Celsius, radiator fouling and air filter restriction can take 10 to 15 per cent off usable output. The precise figure comes from the engine data sheet, and the practical response is to specify a margin and clean radiators and filters on a schedule.
Can solar reduce diesel use at a mine?
Yes, for sites that run through the day. A solar array controlled together with the generators can displace a significant share of daytime fuel, and adding battery storage lets the generators switch off during low-load periods. Payback depends on delivered fuel cost and site hours.
Technical content reviewed by Srinivas Reddy, Managing Partner, Reddy Generators. Last updated 19 October 2026.