In short. Food and beverage plants lose product, not just time, when power fails: refrigeration drifts, ovens and fryers cool mid-batch, CIP cycles abort and packaging lines jam. Generator power is planned around the functions that protect product and hygiene first, with refrigeration compressors, process cooling, water and air treated as a staged restart sequence, and the set installed so that exhaust, fuel and noise stay clear of production areas.
Where the loss actually happens
An outage in a snack, bakery, beverage or ready-meal plant has four distinct costs. Product in process is lost when a continuous oven, fryer, retort or pasteuriser stops mid-cycle and cannot be restarted without scrapping what is inside. Stored product is at risk when cold rooms and blast freezers warm beyond their limits. Hygiene is compromised when a clean-in-place cycle aborts and lines must be re-cleaned before use. And the restart itself costs hours when packaging lines, labellers and inspection systems have to be cleared and re-homed. Plants in the food parks around Hyderabad and the beverage bottlers across Telangana and Andhra Pradesh therefore need a generator plan written from these consequences, not from the connected load. The framework we use is described in generator sizing.
| Function | Consequence of interruption | Priority | Notes for the generator |
|---|---|---|---|
| Cold rooms, blast freezers, chilled process water | Product out of temperature, HACCP breach | High | Compressor restarts are the largest steps; stage them |
| Continuous ovens, fryers, retorts, pasteurisers | Batch scrapped, heating medium damaged | High for controlled stop or hold | Electric heating is heavy; gas-fired units need only fans, pumps and controls |
| CIP, water treatment, boiler feed and auxiliaries | Hygiene cycle lost, boiler trips | High | Pumps and dosing; boiler burner controls on UPS |
| Compressed air | Valves, fillers and packaging stop | High | Compressor start against pressure; unloaded start needed |
| Packaging, labelling, inspection | Jams, re-homing, lost traceability | Medium | Servo drives and PLCs on UPS; motors on generator |
| Lighting, HVAC for staff areas, offices | Inconvenience | Low | Shed and restore last |
Refrigeration is the dominant generator load
In most food plants the refrigeration plant is the largest single load and the most difficult to restart. Ammonia or freon screw and reciprocating compressors, condenser fans, evaporator fans and glycol pumps all want to return at once after a transfer. Reciprocating compressors started against system pressure draw heavy starting current; screw compressors on slide valve or VFD control start more gently but then load up quickly. The refrigeration PLC should be set to restart compressors one at a time with the unloaders engaged, and the generator sized for the running refrigeration load plus the largest single compressor start.
kVA_set ≥ (P_running / PF) + kVA_start_largest − kVA_running_largest
P_running is the total running kW once everything is back, PF the plant power factor, kVA_start_largest the starting kVA of the largest compressor and kVA_running_largest its running kVA, which is subtracted because it is already counted in P_running. A worked example (illustrative): a plant with 420 kW of essential running load at 0.85 power factor (about 495 kVA), whose largest compressor is a 90 kW reciprocating unit starting at roughly 5 times full-load current unloaded (about 560 kVA start against 110 kVA running), needs a set able to accept about 495 + 560 − 110, or roughly 945 kVA transiently if that compressor starts last. Starting it first, when the bus carries only 150 kVA of pumps and controls, reduces the peak and allows a smaller set. Sequence is cheaper than kVA. See motor starting and cold storage power.
Thermal processes and controlled stops
Electric heating is a poor candidate for standby. A 300 kW electric fryer or a bank of electric ovens on a generator doubles the set size for a load that could instead be held or brought down safely. Gas-fired ovens, fryers and boilers need only their combustion fans, circulation pumps, burner controls and extraction on the generator, which is a small fraction of the thermal rating. The plant should decide for each thermal process whether the generator provides continuity, a hold at temperature, or a controlled stop that protects the equipment and the heating medium, and should document the restart conditions with the equipment supplier. Boiler and burner management controls belong on a UPS so they do not lock out during the transfer.
Hygiene, siting and fuel
Generator installation in a food plant has constraints that a general factory does not. The set should sit outside production and storage areas, with the exhaust discharged away from air intakes, loading docks and open-air processes, because combustion products and odour can taint product. Fuel storage must be bunded, away from ingredient stores and drainage that leads to the plant’s effluent plant, and the refuelling route should not cross hygiene zones. Noise limits apply where the plant adjoins housing, which in the Hyderabad periphery is common, so acoustic enclosures and exhaust silencers are specified for the night-time limit. Pest control around the enclosure and cable entries is part of the installation, not an afterthought. See acoustic engineering and acoustic enclosures.
Testing, records and temporary power
Food safety systems want evidence. A transfer test under load every month, with cold room temperatures logged before, during and after, gives the quality team a record that the backup works and shows how long each store took to recover. An annual load bank test to rating confirms the set can still carry the refrigeration restart. Planned refrigeration or electrical maintenance that takes the permanent supply or the main compressors out of service is a case for temporary power sized for the storage loads for the duration; the cable route, earthing and a transfer test are agreed before the permanent supply is isolated. See rental power for planned outages. The power handback should be explicit: electrical readiness is confirmed by the generator engineer, and process and hygiene readiness by the plant’s own procedures.
Common mistakes
- Letting all refrigeration compressors restart together after transfer. The combined inrush trips the set and the cold rooms warm during a second, longer outage.
- Putting electric ovens or fryers on the generator by default. The set doubles in size for a load that a controlled stop would have protected at no cost.
- Siting the exhaust near an air intake or loading dock. Product picks up odour and the quality team traces it back to the generator.
- Leaving burner and refrigeration controls off the UPS. They lock out during the ten-second transfer and need a manual reset while product waits.
- Running a weekly no-load test and nothing else. The compressor restart has never been seen on generator and fails on the first hot afternoon.
What to send us
Send the refrigeration plant schedule with compressor types, kW and starting arrangement, the list of thermal processes with their fuel and the decision on hold or stop, the cold store inventory and temperature limits, and a layout showing where a generator could stand relative to production, intakes and neighbours. For an existing set, add nameplate and controller photographs and the record of what happened during the last long outage. Send your application details and we will return a staged restart sequence for your refrigeration and process team to check.
Questions engineers ask
How long can a cold room hold temperature without power?
It depends on insulation, how full it is, door openings and the outside temperature, and ranges from under an hour for a busy chiller in summer to many hours for a full, closed freezer. Measure it during a planned test rather than assume it, and set the generator start and compressor restart within that time.
Should the whole production line run on the generator?
Rarely. Most plants protect refrigeration, water, air, hygiene cycles and controls, hold or stop thermal processes safely, and resume full production on the DISCOM supply. Running everything on diesel costs far more than the production lost in a typical outage.
What about the beverage filling line and its servo drives?
The PLCs, servo controllers and inspection systems go on a UPS so the line keeps its position and data through the transfer. The conveyor and pump motors return on the generator in sequence after refrigeration and air.
Can the generator affect food safety directly?
Only through siting and fuel handling. Exhaust near intakes, diesel spills near drains or ingredient stores, and openings in the enclosure that admit pests are the risks, and all three are managed in the installation design.
Technical content reviewed by Srinivas Reddy, Managing Partner, Reddy Generators. Last updated 19 October 2026.