Backup power for vaccine and pharma refrigerators in India

The first line of defence: hold-over

Before any battery or generator, the cabinet itself buys time. Hold-over is how long it stays in range after power is lost. India's immunization programme relies on this through ice-lined refrigerators, whose frozen water-pack lining keeps the cabinet cold; its handbook describes ILRs keeping vaccines safe with at least 8 hours of continuous electricity in 24 hours.

For ordinary pharma refrigerators, hold-over is shorter and depends on insulation, how full the cabinet is, room temperature and, above all, whether the door stays shut. During an outage, the most effective action costs nothing: keep the door closed.

Backup options compared

Sizing an inverter or UPS correctly

A refrigeration compressor draws several times its running current for a moment when it starts. An inverter sized only for the running load may trip every time the compressor kicks in — leaving the fridge off exactly when you need it. Ask the refrigerator supplier for running power and starting current, and give those to the inverter supplier.

Then size batteries for runtime. Work from the fridge's measured energy use per day, the length of outage you want to ride through and the battery's usable capacity, and remember that a hot room makes the compressor run longer. Avoid sharing the inverter with air-conditioners, pumps or heaters that could overload it.

Generators

• Choose automatic starting with an automatic changeover panel, so the fridge isn't waiting for someone to arrive. India's programme uses DG sets with auto mains failure panels for walk-in cold rooms.
• The US CDC suggests testing a vaccine backup generator quarterly, servicing it annually and keeping fuel for at least 72 hours of continuous running.
• Check that the refrigerator restarts cleanly after changeover; restart delays protect compressors from rapid on-off cycling.
• Keep fuel, service and test records with your cold chain records.

Voltage protection is part of the plan

Power often returns with sags and spikes, and generators can deliver unstable voltage under changing loads. India's cold chain handbook says electrical cold chain equipment should never run without a voltage stabiliser, that one stabiliser should not serve several machines and that faulty stabilisers should not be bypassed. Match any stabiliser's input range to your site's real supply.

Alarms that work when the power doesn't

An alarm powered from the same socket as the fridge falls silent at the worst moment. Choose loggers and alarms with their own batteries, and remote alerts by SMS or app that continue during an outage. Make sure someone receives those alerts out of hours and knows what to do.

A written outage plan

• Who is responsible during working hours, nights and holidays, with phone numbers.
• How long each cabinet typically holds in range, at summer and winter room temperatures.
• At what point stock moves to backup storage, and where that is.
• How stock is packed for a move — conditioned coolant packs and insulated boxes, never frozen packs straight against freeze-sensitive products.
• What gets recorded: start and end of outage, temperatures and actions taken.
• Who decides whether stock affected by an excursion can be used — the programme, manufacturer or regulator, not the person on shift.