What is Power Transformer Protection?

Power transformers are an important part of our lives. We may drive past it and never even realize that it is an important component in supplying electricity. You must also know that they are pretty expensive. Any faults in the transformers will lead to adverse reactions that lead to further spending. So, innovators had one of the best ideas ever; to develop transformer protection systems that keep them within safe limits.

Being an experienced power transformer manufacturer, we have decided to shed some light on the topic. We will discuss some of the common types of transformer faults and how to protect them.

Transformer Protection Types

1. Protection from overheating:

You might have experienced blackouts due to an overload in the nearby transformer. Sometimes when a transformer overloads, it tends to produce heat and thus damages the insulation. If not protected against overheating, the transformer might fail abruptly. To tackle this problem, we install a thermometer that measures the oil/winding temperature. When the temperature limit crosses the critical point, an alarm goes off, which helps prevent further damages to the circuit.

2. Protection from overcurrent:

To protect pieces of equipment connected to the grid, overcurrent transformer protection systems are necessary. The relay works by detecting the changes in the transmission. If it exceeds a certain limit, it prevents any contacts from closing. Thus, having hundreds of electrical equipment as well as the transformer.

3. Protection from differential current:

The transformer’s operating coil matches both sides of the coil, and thus no difference in charges occurs. But when something is off with this balance, the two coils produce differential current. A differential relay identifies this fault and initiates the circuit breakers to save the main transformer.

4. Protection from resolved gas:

In case of faults, the windings may sometimes produce sparks. These sparks create heat and evaporate the oil into gas. The severity of this gas buildup is directly proportional to the severity of the damage in the windings. Hence, to determine the nature of the fault, you should analyze the gas.

Most transformers make use of Buchholz Relay. When any fault occurs, the gas naturally builds up and flows through this relay. If the gas flow is too high, the relay detects it and shuts down the transformer. It also sets off an alarm that helps notify the service personnel. Buchholz relay is also capable of setting off different alarms for different problems.

5. Protection from over-flux:

A power transformer manufacturer creates a transformer to operate at a fixed flux level. A change in that flux level will induce heat and thus hinder the smooth operation. Thus, it is vital to incorporate over-flux protection systems.

Most transformers make use of a relay to help detect the over-flux. Flux generally occurs due to the change in the voltage or the frequency. Hence, the relay calculates a ratio between the two. If the value exceeds a certain limit, the relay triggers the circuit breakers to save the other components of the power transformers.

6. Protection from lightning:

Lightning often poses a major threat to all electrical circuits. It goes without saying that we need to install transformer protection systems for something so expensive. A popular method is the use of surge arresters. It stands like a pillar on top of the transformer tank. When lightning hits, it transfers the surge into the grounding terminal. Thus preventing the lightning from disrupting the transformer.

Typically, it also prevents any lightning surges caused by strikes near the transformer. By installing lightning protection systems, you save hundreds of dollars worth of equipment. You also save yourself from the rewiring charges for burnt transmission lines.


Every transformer, no matter the type, encounters faults during its lifetime. So it is important to take preventive measures such as installing transformer protective systems. It can save you money, as well as keep you safe from fiery accidents.

At Electric Power Inc., we manufacture custom dry-type transformers to suit your needs. We design all our transformers with safety as our top priority. Get in touch with us today!

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