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Top 10 things to know before selecting a Power Transformer

Before you choose a power transformer, you must know certain essential things about a transformer and its working principle. Essentially you must know the voltage power output you need in your country. For example, voltage in different parts of the world differs. United States and Canada run on 110/120 volts and other parts of the world runs on 220/240 volts. Usually industrial plants use 440 to 480 volts.

Choose the transformers based on the load type and try to use few transformers as possible in order to effectively reduce voltage drop. Once you determine the load size and nature of the load, then choosing a transformer is quite easy. Even for industries, transformer selection seems to be very easy once you know the load size and nature of the load.

Before selecting a power transformer, determine the primary voltage and frequency, the secondary voltage and the capacity required. Determine the individual loads based on operational requirements, and determine the kVA of each. Then determine the motor loads. After manipulating the individual calculations, add all of them and determine the maximum coincident load. Once you have determined the maximum load you can expect, you can select the transformer based on that. Choose a transformer with higher voltage and smaller amperage so that the loss due to resistance is less.

Determine the size of your power transformer based on the maximum load you can expect. You must decide the size of the transformer based on the size of the generating units used. The use of three phase transformer is cheaper, weightless and compact than using three single phase transformers. But the use of single phase transformers occupies less space and makes the system more reliable and easy to maintain and handle.

You must also consider certain other factors while choosing a transformer based on the purpose for which use the transformer. Some of the other factors are pole/pad mounted, indoor or outdoor usage, primary voltage, Secondary voltage, wire configuration, power factor and efficiency, impedance, temperature rise, case style, space requirement, location, seismic requirement, basic impulse level, dry or liquid-filled type. You must consult with a manufacturer in order to choose the right power transformer for your application, based on these factors.

When choosing a power transformer, you must consider several factors as said above. The operating condition, available transporting facility, cooling methods, impedance, and insulating level must be considered. You must also consider losses at different power factor loads and voltage regulation factor for different power factors. The factors such as weight, dimension and cost must also be considered.

Estimate the de-rating of the transformer using the load’s K-factor. You can calculate the K-factor based on the harmonic spectrum of the load current. This in fact indicates the excess losses experienced in a traditional wire wound transformer. You must de-rate the transformer in an appropriate manner when using existing or standard transformers. On the other hand, specially constructed or K rated transformers must be selected for new installations.

When choosing transformer, you must consider the appropriate standards and references, and must compulsorily work with your manufacturer before deciding the power transformer for your application. By choosing the right power transformer for your application, you can reduce the transmission losses and the transmission cost by a significant amount.