How to Choose Transformer Capacity?
Transformers come in standard ratings. Choosing capacity means picking the standard size that best fits your load today, your peaks, and your plans, without paying for capacity you will never use.
This guide explains how to think about headroom, load factor and lifecycle cost.
Transformers come in standard ratings. Choosing capacity means picking the standard size that best fits your load today, your peaks, and your plans, without paying for capacity you will never use.
This guide explains how to think about headroom, load factor and lifecycle cost.
Standard distribution ratings
Common three phase distribution ratings are 500, 1000, 1600, 2000, 2500 and 3150 kVA. Selecting a standard rating keeps cost, lead time and future replacement straightforward.
Think in three numbers
Peak demand. The maximum diversified load you expect, the transformer must cover this comfortably
Average load. Determines where you sit on the loss curve and how efficient the unit is in practice
Planned growth. Determines the headroom you should build in now
The cost of too little capacity
Overload protection trips, voltage dip on motor starting, accelerated insulation ageing, and an expensive unplanned upgrade with production downtime.
The cost of too much capacity
Higher capital cost, higher no-load losses every hour of every year, larger footprint, higher fault level, and sometimes worse part-load efficiency.
A practical approach
Calculate maximum demand, add documented growth margin, check motor starting and harmonics, then round up to the next standard rating. If the result is only marginally above a standard size and growth is unlikely, take the smaller size and monitor.
Frequently Asked Questions
Related Products, Applications and Support
Not sure which rating fits your project? Send us your load list and we will size it for you, or email info@xsdfftransformer.com, call +86 158 6789 7761 or WhatsApp +852 5416 2620.