Types of power transformers

Power transformers can be divided into several types based on the following characteristics and indicators:

Cooling type. There are dry and oil transformers. The first option is air-cooled and is used where environmental and fire safety requirements are increased. The second option is a housing filled with oil with dielectric properties, into which a core with windings is immersed;

Climatic design: external and internal options;

Number of phases. There are three-phase (the most common) and single-phase;

Number of windings. There are two-winding and multi-winding options;

Purpose: increasing and decreasing.

An additional criterion is the presence or absence of an output voltage regulator.

Transformer structure

The main parts of the voltage converter are:

magnetic circuit;

high and low voltage windings;

tank;

inputs and outputs.

Additional equipment includes:

expansion tank;

exhaust pipe;

blow-out fuse;

control and alarm devices.

The magnetic core is necessary for fastening all parts of the device. It is a kind of skeleton of a voltage converter. Its second task is to create a direction of movement for the main magnetic flux. Depending on the features of fastening the windings to the core, the magnetic circuit of the transformer can be of three types:

armored rod;

armored;

core.

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Transformer oil is a very important element in the device. It is not used in low-power (dry) transformers. At medium and high power its use is mandatory. Transformer oil has two main tasks:

cooling of windings that heat up due to current flowing through them;

increased insulation.

The expansion tank is installed in transformers with a high voltage winding of more than 6 kV and a device power above 75 kVA. Taking heat from the windings, the transformer oil gradually heats up and expands. Its excess goes into the expansion tank. The function of the expander is to protect the oil from oxidation and moisture.

Inputs and outputs are needed to connect the ends of the windings to power lines. They are located on the tank lid. They are a glass or porcelain insulator with a conductive copper rod inside. The primary winding is attached to the inputs, and the secondary winding is attached to the terminals.

There is a voltage switch (antzapf) located on the tank lid. Using this device, you can change the number of connected turns of windings at a time in three phases. This manipulation allows you to increase or decrease the output voltage as needed.

The function of the exhaust pipe is to prevent damage to the tank when emergency conditions occur. In the event of a breakdown or short circuit, the oil rapidly heats up and gases appear. Due to the presence of an exhaust pipe, the tank does not burst under significant pressure, but only the glass membrane in the pipe is damaged. In this case, oil and gases escape.

The breakout fuse is installed next to the inputs and outputs. Its purpose is to protect low-voltage networks from the appearance of high voltage in them.

A thermometric alarm is necessary to monitor the temperature level of transformer oil, as well as to give a signal in case of overheating.