# 10 factors to consider when buying a transformer

Our team of developers and manufacturers of transformers "Elsta" wants to offer in this article the basic specifications of the transformers that are of interest to the customer - the buyer, technical characteristics, installation requirements and operating conditions.

Here is a list of the most important questions regarding the technical characteristics of an electrical transformer.

## How many phases are required?

Before choosing a transformer, you need to decide which transformer you need - single-phase or three-phase. This will be determined by the parameters of the equipment you are using and the parameters of your network. For example, most people in the CIS countries use only one phase, since this is enough for most small devices and machines, while three-phase transformers are more common in industrial plants, and are also used in the production cycles of small and medium-sized businesses.

When designing a transformer, you must know the input and output (secondary) voltages. This is determined by the parameters of the network to which the transformer is connected and the voltage of the equipment you are using. For example, the input (primary) and output (secondary) voltages vary depending on the input power source and power consumption. For example, the same equipment can be connected to both the American 110-120 V network and the European 220-230 V, naturally, for it to work correctly, a transformer is needed, either increasing 110-220 V or decreasing 220-110 V. Frequency of the transformer is usually determined by the network frequency. Sometimes the input frequency is different from the output one. This is usually done with a frequency converter at the output of the transformer.

For example, most transformers operate at 50 Hz, however, if the equipment is imported from the USA the frequency will be 60 Hz. Here you will need a specially designed and manufactured transformer.

## Transformer power

An important factor when choosing a transformer is the size and nature of the load. The power of the transformer is approximately determined by the product of voltage and current in the primary winding. Why approximately? The load can be active (heater, for example), active-reactive, like most consumers - electric motors, etc. it is necessary to take into account the reactive power, in this case the total power of the transformer will be greater. For the correct calculation of the transformer, you can contact the specialists. An important factor is the switch-on-switch-off diagram. If the transformer is turned off most of the time or operates in no-load mode, and the rated load is short-term, the transformer can be designed for a lower power and vice versa if, at a constant rated load, the transformer is always in transient on-off modes (at which currents increase by 3- 5 times), it is necessary to lay a power reserve.

## Purpose of the transformer

When ordering a transformer, it is also necessary to take into account where it will work, this determines the class of insulation, constructive in a sealed case or outdoors, under water or in a dry room. The so-called K-factor is also important - harmful harmonics, which the transformer will cut off and transfer to the network a pure sinusoid or an autotransformer, which will transmit all the interference to the secondary circuit.

## What environment will the transformer be used in?

It is important to understand where the transformer will be used indoors or outdoors, in a chemically aggressive or neutral environment, high in the mountains or at sea level, in transport or stationary, near sea water or not. The ambient temperature also plays a significant role. If the cooling conditions of the transformer are not met, and it constantly operates in overheating mode, it is necessary either to reduce the load power, or calculate a more powerful transformer, or connect another transformer in parallel to the load to unload the main one. If the transformer is used in a chemically active or humid environment, one of the inexpensive ways to remove the influence of harmful environmental components is to place the transformer in a sealed case, but it is important to meet all temperature requirements in order to prevent it from overheating and premature failure.

## What size requirements should the transformer meet?

It should be borne in mind that, depending on the design, each transformer has a so-called "overall capacity". The toroidal transformer has an optimal design today - it has no equal in terms of mounting and cooling. There are situations when, for some reason, it is impossible to execute and place a transformer with the required parameters in a specific place. In this case, it is necessary to make several transformers and make the so-called "transformer assembly". The main problem in this case is the absolute precision of manufacturing. The transformers must be absolutely identical.

## What kind of winding connection is needed?

In the case of using a three-phase transformer, you need to know how to connect the windings of the transformers (phases): in a star or triangle. Also, the primary and secondary windings can be connected in different ways, depending on whether a neutral is needed or not.

The correct choice of the transformer determines its long-term operation and reliability, as well as the reliability of the connected equipment. Our company is ready to assist you in calculating and manufacturing the required transformer as soon as possible (in our case, up to a maximum of 10 days).

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