Servo stabilizers and transfer switches for cold storage
Compressor motors are unforgiving of low voltage, and the stock in the chamber does not care whose fault the outage was.
What actually goes wrong
A refrigeration compressor running at low voltage draws higher current to deliver the same torque, and the motor windings heat. Do that daily for a year and the motor fails in the summer, which is exactly when you cannot afford it. Cold storage sites are also frequently on rural or semi-rural feeders where the voltage profile is at its worst.
Working in cold storage & food processing
What to get right
The decisions on this list are the ones that are expensive to change after the equipment is on site.
Motor starting current
A DOL-started compressor pulls six to eight times full-load current. Size the stabilizer for the inrush, not the running load.
Single phasing protection
The fastest way to destroy a three-phase compressor. Single-phase preventer protection belongs in the panel, not as an afterthought.
Fast changeover
The tighter the transfer window when the supply swaps over, the less the chamber temperature drifts while it happens.
Control and monitoring backup
The compressors can wait for the DG. The temperature loggers, alarms and controls should not — that is a small UPS, not a large one.
Outdoor and washdown
IP55 enclosures where equipment sits outdoors or in a washdown area.
Rural feeder profile
Wider input windows than the standard 340–480 V are often needed. Log the incoming supply before specifying.
What we supply into this sector
Servo Voltage Stabilizer
5 kVA to 500 kVA, air or oil cooled, correcting to ±1% output. The right first fix when the MIDC feeder swings all day and the equipment keeps tripping on undervoltage.
Automatic Transfer Switch (ATS)
The supply you are on fails, and the load moves to the one that has not — with nobody at the panel. 10 A to 150 A, single phase and three phase.
Online UPS
True double-conversion topology from 3 kVA to 200 kVA across three series, with single-phase or three-phase output. Zero transfer time, pure sine output held to ±1%, and up to 96% efficiency. Built and load-tested in Pune.
Isolation Transformer
Galvanic separation between supply and load, with electrostatic shielding that attenuates common-mode noise by 100 dB or better. 1 kVA to 500 kVA.
Through the life of the machine
Questions we get asked
Anything not covered here, call us — most of it is faster to answer on the phone.
01What size servo stabilizer does a cold storage unit need?
Size against compressor starting current, not the running load. A plant with 100 kVA of running load and DOL-started compressors may need 200 kVA or more of stabilizer to hold voltage through the inrush. Tell us the compressor ratings and the starting method — DOL, star-delta or soft starter — and it changes the answer substantially.
02Does a cold store need a UPS as well as a DG?
A small one, yes, though not for the compressors. The controls, temperature loggers, alarms and communications should ride through the DG start window so you keep an unbroken temperature record and any alarm during the changeover still reaches someone. That is a few kVA, not a few hundred.
03What does a power failure actually cost a cold store?
Rarely the electricity, and often the load. A well-insulated chamber holds temperature for a while, so a short outage may cost nothing — but the risk is not linear. The point at which product moves outside its specified band depends on chamber size, how full it is, ambient temperature and how often doors open, and once that line is crossed the loss is the stock, not the downtime. Knowing your own hold time is the number that should drive the backup decision.
04Do refrigeration compressors need a UPS or a generator?
A generator, in almost every case. Compressors are large motor loads with heavy starting current and long run times, and a UPS sized for them is rarely economic. The usual split is a generator for the refrigeration plant and a UPS for the controls, monitoring and alarms — so the plant restarts correctly and you know what happened while it was off.
05Why do compressors struggle at low voltage?
Because a motor draws more current to deliver the same torque as voltage falls, which means more heat in the windings, and a compressor starting under load is the worst moment for it. Sustained low voltage shortens motor life and can prevent a start entirely at the moment the chamber most needs cooling. Where the incoming supply sags predictably, a servo stabilizer ahead of the plant is the straightforward fix.
06Should the temperature monitoring be on separate backup?
Yes, and it is the cheapest part of the installation. Monitoring and alarms draw very little, so a small UPS keeps them alive through an outage that stops the refrigeration — which is exactly when you need to know chamber temperature and need the alarm to reach somebody. A cold store that loses its monitoring at the same moment it loses its cooling has lost the evidence as well as the product.
We will do the load grading with you
Site survey, load list and a single-line diagram before anything is quoted. That is where the specification is actually decided.