As an essential piece of electrical equipment, the transformer is one of the most important components in the energy system, responsible for converting and distributing electrical energy within the grid. However, overloads may affect the normal operation of transformers and can even lead to severe accidents or fires. Therefore, it is crucial to adopt effective measures to protect these devices.

Consequences and Causes of Transformer Overload

The causes of transformer overload are diverse. Overload may occur due to improper load pattern selection, calculation errors, rising operating temperatures, or mismatches between equipment characteristics and rated values. Regardless of the cause, it is essential to take preventive measures in advance to avoid serious consequences.

Transformer Overload Protection: Types and Principles

Emergency overloads can be divided into two main types: short-term overloads and long-term overloads. Short-term overloads occur regardless of prior loads, cooling system temperature, or equipment location; whereas long-term overloads depend on previous load conditions and take into account the demands and requirements of the power system. It should be noted that some allowable overloads do not affect transformer operation, but exceeding these limits may lead to emergencies such as winding short circuits, equipment damage, or even outages.

Overload Protection Methods

There are several effective methods to prevent transformer overload:

• Fuses:
  A simple and widely used method, fuses are installed at the input and output of the transformer. When the current exceeds the preset value, the fuse automatically disconnects the device.

• Protective relays:
  These devices monitor current, temperature, and voltage parameters. If preset limits are exceeded, they automatically disconnect the transformer.

• Automatic switches:
  These disconnect the device in case of overload or short circuit and automatically reconnect it after the cause of the overload is eliminated.

• Current cutoff:
  This method provides disconnection when internal faults occur in the transformer, helping prevent severe damage.

• Gas relays:
  Used in oil-immersed transformers, these detect changes in the gas environment, which may indicate overload conditions.

Comparative Table of Transformer Protection Methods

These are some of the key methods that help prevent transformer overload and ensure the safe operation of the power system. You can find transformers equipped with reliable overload protection methods in our transformer product catalog.