Stabilisers and surge protection for commercial refrigeration in India

What poor power does to a compressor

• Low voltage: the motor draws more current to do the same work, runs hot, and may fail to start, sitting stalled until the overload trips.
• High voltage and spikes: stress on motor insulation, start components and the electronic controller.
• Quick restart after a cut: the compressor tries to start against high pressure, draws locked-rotor current and may trip or burn out.
• Repeated brownouts: frequent overload trips age the start relay, capacitor and windings over months.

Do you need a stabiliser?

Start with the unit's specification: the manufacturer states an operating voltage range. Then measure your supply over several days, including peak hours. If the voltage stays inside the stated range, a stabiliser adds little. If it regularly falls below or rises above it, protection is worth having.

Ask the supplier directly whether the unit needs a stabiliser and whether using one, or not using one, affects warranty support. Do not assume either way.

Measure before you buy anything

A one-off reading with a multimeter in the morning tells you very little. Voltage in Indian markets and kitchens often looks healthy at 10 a.m. and sags badly at 7 p.m. when air conditioners, lighting and cooking loads peak across the area. Ask your electrician to log voltage over at least a few days, or take readings yourself at fixed times using a plug-in voltage meter.

Record the lowest and highest values you see, the time they happen and whether lights flicker when the compressor starts. These numbers decide whether you need a stabiliser at all, what input range it must cover and whether the real problem is local, such as a loose connection or undersized cable, rather than the incoming supply.

• Readings at morning, lunch service, early evening and late night.
• Note the voltage drop at the moment the compressor starts.
• Check the reading at the panel and at the socket; a big difference points to wiring, not the grid.

Choosing a stabiliser

• Rating: size it for the unit's starting current, not just its running wattage; ask the supplier for the recommended capacity.
• Input range: it must cover the lowest and highest voltages you actually measured.
• Time delay: a built-in delay before power is restored to the load protects the compressor after a cut.
• One per unit is easier to manage and avoids one failure taking down several cabinets.
• Servo or relay type: servo stabilisers correct smoothly; relay types step in increments. Either can work if correctly rated.

Other protection that helps

A voltage protection device cuts supply when voltage goes outside safe limits and reconnects after a delay. It does not correct voltage, but it is often enough where the supply is mostly good with occasional extremes. Many commercial controllers also include a compressor restart delay. Surge protection at the distribution board limits spikes from switching and lightning, and protects electronics across the premises.

Placing the stabiliser

• Mount it on a wall or shelf, not on top of the refrigeration unit or in its exhaust air.
• Keep it away from water, steam and floor washing.
• Give it ventilation; stabilisers produce heat too.
• Keep cables short and use the correct plug and socket ratings — no adaptors.
• Label it so staff do not switch it off or borrow it for another appliance.

Power cuts and restart

After an outage, many appliances restart at once. Staggered restarts, either through stabiliser delays or controller settings, reduce the combined current surge and protect generators and inverters. Keep doors closed during a cut; a well-insulated cabinet holds its temperature far longer when nobody opens it.

Safety note

Stabilisers and protection devices are part of the electrical installation. Have them selected and installed by a licensed electrician, and never bypass a protection device to get a unit running.