Load Capacity for Dry Type Transformers

Dry type transformers harness air cooling to maintain safe, efficient temperatures as they convert high primary voltages to the right voltage for your application. Industrial, commercial and utility companies favor them as they excel at a wide range of voltage conversions.

Ensuring long-lasting, efficient performance depends on knowing and being able to calculate your transformer’s load capacity.

What Is Dry Type Transformer Load Capacity?

Load capacity describes the maximum amount of power a dry type transformer can handle. Manufacturers usually give load capacity ratings in kilovolt-amperes (kVA).

Dry type transformers have temperature and insulation limits. Up to these limits, they can operate safely for a period of time. Beyond them, they are vulnerable to overheating and breaking down — and the farther over capacity they go, the faster damage will occur.

Load capacity tells you how much power a transformer can convert and supply to a system while remaining within its temperature and insulation limits. A transformer with a higher load capacity can serve electrical equipment systems that demand more power.

Why Does Load Capacity for Dry Type Transformers Matter?

Dry type transformers are essential in supplying power to electrical systems for facilities in countless sectors. A safe and consistent power supply depends on using these transformers correctly. Load capacity informs how you can use your transformer for maximal durability and reliable results.

Taking load capacity into account helps ensure:

Optimal distribution: Matching the transformer’s load capacity to the load requirements keeps equipment running at optimal efficiency and reduces the potential for damage to equipment or the transformer itself.
Electrical safety: Respecting a transformer’s load capacity minimizes risks of electrical failures and hazards.
Temperature regulation: The dry transformer’s air cooling system works best while the transformer functions within its load capacity. Pushing the transformer beyond its capacity can cause it to overheat and break down, resulting in costly damage and power supply interruptions.
Energy efficiency: Using a transformer with a sufficient load capacity minimizes energy losses during conversion. This promotes energy efficiency, which is important for financial and environmental reasons.
Enhanced reliability: Considering load capacity when powering a system through a transformer maximizes the transformer’s life span and helps maintain a dependable energy supply.

What Determines Dry Type Transformer Load Capacity?

Several factors impact the power load a dry type transformer can handle:

Whether it is a single-phase or three-phase transformer
How it’s ventilated or cooled
Build materials
Cooling system efficiency
Transformer size
Amount of insulation
Transformer winding voltages
Environment

How to Calculate Load Capacity for Dry Type Transformers

You can calculate the necessary dry type transformer load capacity in kVA by following a few simple steps. Check your electrical schematics for the information you need to complete these steps:

Note the load voltage (V) and the required load phase current (L) indicated on your schematic.
If L is not specified on the schematic, divide input voltage by input resistance to calculate it.
Find the load’s kilowatt (kW) power requirements through the formula V * L / 1000.
Divide the load’s kW power requirement by its power factor, which is usually 0.8.
The result is the necessary transformer kVA rating.

Your result will likely contain decimals. Since most manufacturer load capacity ratings are expressed in whole numbers in multiples of 5 or 10, round your answer up to the nearest 5 or 10. This way, you’ll select a transformer with a load capacity slightly higher than required. This ensures the transformer can handle the load’s power demands. Stick to this 5kVA or 10kVA rounding, as exceeding it could land you with an oversized transformer that compromises your system’s efficiency and safety.

For example, if your system has a V of 189.3 and an L of 50, V * L / 1000 = 9.465. Then. 9.465 / 0.8 = 11.831. This result means you need a transformer with a load capacity rounded up to 15 kVA.

The load capacity formula above assumes you are using a single-phase transformer. If you intend to use a three-phase transformer, you need to adjust the calculation by introducing an additional step.

For an accurate load capacity result for three-phase transformers, multiply the product of the voltage and amperage by the square root of 3 (shortened to three decimal places) — a constant of 1.732. A three-phase transformer’s required load capacity in kVA = (V * L * 1.732 / 1000) / 0.8.

It’s also important to note that a system’s starting current usually exceeds its running current. Dividing by the power factor in the formula helps you account for that. If you need to start your transformer frequently — more than once per hour — the transformer will need a greater load capacity.

Specialized loads like medical equipment may also affect your transformer’s kVA load capacity requirements. In these exceptional circumstances, accurately determining the required transformer load capacity is crucial but challenging. Seek the advice of a professional transformer company to find a transformer with the right load capacity for your needs.

Why Trust Us for Transformer Expertise?

ELSCO Transformers has been engineering, repairing, building and selling transformers to companies across North America since our founding in 1912. Each of our key team members has over 21 years of experience working with transformers.

ELSCO Transformers’ experts have gained years of experience with transformers across industries, including but not limited to:

Manufacturing
Education
Hospitals and medical centers
Government
Utilities

We have been building our own dry type transformers since 1988, without a single product failure arising from our work in nearly four decades. We are committed to drawing on our extensive experience and expertise with dry type transformers to answer your questions and meet your needs.

Choose ELSCO for Dry Type Transformers

If you are looking for dry type transformers with the right load capacity for your application, choose ELSCO Transformers. We design and manufacture our transformers in-house for superior value and performance and ship to any location in the United States.

Our dry type transformers meet or exceed Department of Energy performance standards, running cool and quiet as a reliable part of your system’s power supply chain. Our transformers have an expected useful life span of over 30 years, 50%-100% longer than the industry average. We also offer an industry-leading five-year warranty for added assurance. If you have any questions, our transformer experts are ready to advise and ensure you find the right transformer for your needs.

Browse our catalog of dry type transformers and order yours today.

If you experience an unexpected outage, call our Quick Response Team at 513-275-5781 for a rapid transformer replacement.