How To Identify a Power Transformer? 3 Min Read

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Transformers are a passive component found in many electrical applications and circuits; they are used to transfer electrical energy from one electrical circuit to either another one or multiple ones. The transformer component has many types, such as power transformer, step-up transformer, step-down transformer, and many other types. So, how to identify a power transformer?

How To Identify a Power Transformer?

To identify a power transformer, you have to look for transformers that work in transmissions with high voltages; power transformers have different ratings of 200 KV, 33 KV, 400 KV, 110 KV, and 66 KV; in addition, they are rated above 200 MVA. Therefore, they are bigger than the distribution transformers.

The power transforms mainly used in transmission substations and generating stations; they have 100% efficiency. However, the high power ratings can’t be served to the customers directly; the power must be stepped down to the required level using a step-down transformer. The core of the transformer losses a bit of the power over the day.

Therefore, the transformer is not overloaded or fully loaded; each distribution cycle has a load; the copper used must have its load based on the load of the cycle. However, the power transformers solve the fluctuations of the cycle’s load because the power transformers are not installed directly at the consumer’s end.

At low voltage levels, the power transformers are very cost-effective; however, the power transformer’s current decreases when the voltage levels increase, increasing the regulations of the voltage and losses of I2R.

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How To Identify Other Types of Transformers?

To identify other transformers, you have to look for each transformer’s characteristics and where it is used. For example, step-down transformers are used to step down the high powers to make it desirable for the customers.

Step-Down and Step-Up Transformers

Step-down and step-up transformers can be identified throw the turns’ number of the secondary and primary windings and the induced electromotive force. The step-up transformers transform high currents, the AC ones to low currents, and the low voltages to high voltages.

The secondary turns in step-up transformers windings are more than the primary ones; therefore, the secondary voltage is higher than the primary ones, which means it is raised on the output. On the other hand, the step-down transformers transform low currents, the AC ones, to high currents, and the high voltages to low voltages.

The secondary turns in step-up transformers windings are less than the primary turns; therefore, the secondary voltage is lower than the primary voltage, which means it is stepped down on the output.

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Distribution Transformers

Distribution transformers have different ratings of 230 V, 3.3 V, 440 V, 11 V, and 6.6 V; they are also rated lower than 200 MVA. They are used to provide the transformation of voltages at the distribution networks in the power systems by stepping down the voltage level.

The electrical energy is utilized at the customer’s end, and it’s distributed; the distribution transformer’s primary coil is wounded by an enamel cover with aluminum or copper. The secondary of a distribution transformer is made from a thick ribbon of copper and aluminum and is a low voltage high current winding.

The distribution transformer is insulated through oil and resin impregnated paper; oils in transformers are used for many purposes like:

  • Insulation of The Windings
  • Cooling
  • Protection from Moisture

The distribution transformers can be categorized on three different bases, and they are:

  • Insulation Type
  • Transformer’s Mounting Location
  • Supply Nature

Uses of Distribution Transformers

Distribution transformers have several different uses because they are very important for any distribution network; for example:

  • At low voltage like 33KV, they are in pumping stations.
  • Overhead wires used in railways that use AC use distribution transformer as power supply.
  • Single-phase transformers are used in many houses in urban areas; meanwhile, one single transformer may be used for one house depending on the house loads in rural areas.
  • Commercial and industrial areas use several distribution transformers.
  • In wind farms, the electrical energy is generated by windmills and distributed by distribution transformers through substations far from the windmills, so the transformers are used as power collectors.

Insturment Transformers

The instrument transformers are also known as the insulation transformers; they are electrical components used to transform voltage and current levels. When the primary windings have high current and voltage levels, the instrument transformers are used to protect the secondary windings.

Therefore, the measuring instrument relays or energy meters found on the secondary side of the transformer are protected from damage. Instrument transformers have two types:

  • Potential Transformer “PT”
  • Current Transformer “CT” 

The Potential Transformer

The potential transformers are also known as voltage transformers; the voltage transformer’s primary winding is connected across the line that needs to be measured; this line is known as the high line. The secondary side of the transformer is connected to the measuring meters and instruments.

When the voltage is high, the potential transformer is used to step it down to a safe value or limit, and the transformer’s primary winding is grounded or earthed for safety. The ratio of the secondary to primary voltage is 500:120, which means if the applied voltage is 500 volts, the output voltage is 120 volts.

The potential transformed has three different types, the capacitor, which uses a capacitor voltage divider and it’s known as the capacitor voltage transformer “CVT,” the electromagnetic transformer, and the optical transformer, which uses the electrical property of optical materials.

The Current Transformer

The current transformers are used for protection and measuring; the current transformer is used when a high current needs to be stepped down to the required amounts or values. Any measuring instruments such as voltmeters, ammeters, or wattmeters are connected in series with the current transformer’s primary winding.

They enable the meter of the transformer’s secondary side accurately through their accurate phase relation and current ratios; in addition, the ratio in a current transformer is 5:2000, which means if the input is 2000 amperes, the output will be 5 amperes, the current transformer has a significant effect.

Many factors can affect the current transformer accuracy: temperature, Burden, load, rating, saturation, and phase change. 

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Three Phase Transformers

The three-phase transformer is constructed when three single-phase transformers are connected. Their primary windings are connected, and their secondary windings form one secondary winding. The three transformers act like one three-phase transformer.

The three-phase transformers are used for industrial applications’ distribution, transmission, and electric power generation. Therefore, it costs higher to buy one three-phase transformer than to construct one from three single-phase transformers.

Single Phase Transformers

The single-phase transformers are static devices applied to the law of Faraday’s mutual induction; At variation of voltage and constant frequency, the AC power passes from one circuit to another through the transformer. The primary windings are responsible for receiving the AC, and the secondary winding is responsible for connecting the load.

Conclusion

To sum up, you can identify power transformers by looking for transformers that work in transmissions with high voltages; power transformers have different ratings of 200 KV, 33 KV, 400 KV, and 66 KV; in addition, they are rated above 200 MVA. Therefore, they are bigger than the distribution transformers.

The power transforms have 100% efficiency and are mainly used in transmission substations and generating stations. The high power ratings can not be delivered to the customers directly; the power must be stepped down to the required level using a step-down transformer. The core of the transformer losses a bit of the power over the day.

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