Standby Generator Sizing and Power Continuity for Industrial Laundry Plants
A laundry plant sized on running-load kVA alone will frequently fail to start its own machinery once the generator is actually installed, because the motor starting current on a large washer-extractor or extractor at the moment of start-up is several times its running current, and the generator has to survive that spike, not just carry the steady-state load.
Published July 6, 2026 — Stalwart Engineering Technical NotesGrid outages in many parts of India remain frequent enough that a laundry plant running on a fixed production schedule for hospital, hotel, or garment-export linen cannot simply wait them out; standby generation is often not optional but a condition of the service contract with the client. Sizing that generator correctly is less about the plant's total connected load, which is a number every electrical contractor can calculate quickly, and more about the starting behaviour of the largest motors on site, which is where undersized installations actually fail.
Why running load is not the sizing constraint
An induction motor draws several times its rated running current for the first fraction of a second to a few seconds of start-up, before settling to normal running current as it reaches speed. A generator that is comfortably sized for the plant's steady running load can still stall or trip on protection the moment a large washer-extractor motor starts, because the instantaneous starting current demand exceeds what the generator's alternator can supply without an unacceptable voltage dip. This is the single most common design error in laundry plant standby power: sizing to nameplate running kVA and being surprised when the generator cannot actually start the equipment it was sized to run.
The practical fix is either oversizing the generator specifically to absorb the largest single motor start while other loads are already running, or staging motor starts so that large machines do not start simultaneously, which reduces peak starting demand at the cost of a slightly longer time to bring the full plant back online after an outage. Soft starters or variable frequency drives on the largest motors, which are increasingly common for other reasons covered in our note on variable frequency drives, also reduce starting current substantially and make generator sizing considerably easier.
Load shedding and priority circuits
Very few laundry plants actually need every piece of equipment running simultaneously on generator power during an outage; the practical approach is to identify which circuits are essential to keep production moving at a reduced but acceptable rate — typically one or two washer-extractors, one dryer, and the boiler or steam system if the plant is not fully electric — and wire those onto a priority load bank that the generator serves first. Non-essential loads such as office lighting, non-critical HVAC, and secondary machines can be shed automatically by a load management controller if generator capacity is tight, rather than requiring every load in the building to be carried simultaneously and driving up the generator's rated capacity, and therefore its capital cost, to cover a demand scenario that rarely if ever actually occurs.
Automatic transfer switch design
The automatic transfer switch, which detects grid failure and switches the plant's supply to generator output, needs a transfer time and sequencing logic matched to the plant's equipment. A washer-extractor mid-cycle when the grid fails will generally continue safely through a transfer of several seconds, but a transfer switch that closes onto the generator before the generator has stabilised at rated voltage and frequency risks damaging sensitive electronic controls on PLC-based machines. Transfer sequencing that waits for generator stabilisation before closing the transfer switch, even at the cost of a few additional seconds of outage, is the safer design choice for plants with significant electronic control investment.
Fuel supply and run-time planning
Generator run-time capacity should be set against the plant's realistic outage duration profile rather than a token few hours of fuel storage. India's Central Electricity Authority publishes grid reliability data by region that gives a reasonable basis for estimating expected outage frequency and duration in a given location, and that data, rather than a generic assumption carried over from a different site, should inform both generator sizing and on-site fuel storage capacity for plants in areas with a documented history of extended outages.