BASIC PARTS OF A SINGLE-PHASE DISTRIBUTION TRANSFORMER AS SEEN BY THE NAKED EYEBasic parts of a distribution transformer that can be virtually seen.
Distribution transformers constructions are relatively less complicated compared to a substation transformer. Although both have exactly similar principle of operation and that is to transform voltage from a higher level to a smaller voltage level, their basic parts differs significantly.
Distribution transformers are basically categorized into two; pad-mounted and pole-mounted distribution transformers. Pad-mounted distribution transformers are also known as mini-substation transformers. Comparing pad-mounted to pole-mounted, pole-mounted distribution transformers are the type of transformer that we usually see especially in developing countries.
Found below are the basic parts of a single-phase pole-mounted distribution transformers we usually see;
Transformer tank – this encloses the oil insulation and winding of the transformer. Typical transformer tanks can either be in cylindrical or rectangular form. The entire assembly is baked to cure the resin then submerged in a large (usually gray) powder coated steel tank which is then filled with high purity mineral oil, which is inert and non-conductive. The tank is temporarily depressurized to remove any remaining moisture that would cause arcing.
Tank Cover – the tank cover includes rubber gasket to securely seal the transformer winding from the weather. Attached also to the tank cover are the primary bushings of the distribution transformer.
Primary bushings/terminals – the primary terminals are attached to the high voltage side of the transformer. Primary bushings can be in single or double bushing depending whether it is for line-to-neutral or line-to-line application. The basic construction of a primary bushing is made up of the conducting terminals and the ceramic insulator.
Secondary bushings/terminals – the secondary terminals are found perpendicular to the body of the distribution transformer. Some distribution transformers have two, three or four terminals depending on the preference of the user.
Cooling fins/radiators – Cooling fins serves as a heat dissipation device intended to reduce the temperature rise of the liquid insulation (oil). The mineral oil helps dissipate heat and protects the transformer from moisture, which will float on the surface of the oil.
Transformer KVA rating – is the visual indicator of the kva capacity of the distribution transformer designed to be seen from a far.
Pressure Relief Device – although not found in the illustration, pressure relief devices are usually found in a typical distribution transformer intended to release pressure build up once specified limit is reached.
Body Grounding Terminal – this is to have a physical ground connection from the transformer tank for safety purposes.
Distribution transformers constructions are relatively less complicated compared to a substation transformer. Although both have exactly similar principle of operation and that is to transform voltage from a higher level to a smaller voltage level, their basic parts differs significantly.
Distribution transformers are basically categorized into two; pad-mounted and pole-mounted distribution transformers. Pad-mounted distribution transformers are also known as mini-substation transformers. Comparing pad-mounted to pole-mounted, pole-mounted distribution transformers are the type of transformer that we usually see especially in developing countries.
Found below are the basic parts of a single-phase pole-mounted distribution transformers we usually see;
Transformer tank – this encloses the oil insulation and winding of the transformer. Typical transformer tanks can either be in cylindrical or rectangular form. The entire assembly is baked to cure the resin then submerged in a large (usually gray) powder coated steel tank which is then filled with high purity mineral oil, which is inert and non-conductive. The tank is temporarily depressurized to remove any remaining moisture that would cause arcing.
Tank Cover – the tank cover includes rubber gasket to securely seal the transformer winding from the weather. Attached also to the tank cover are the primary bushings of the distribution transformer.
Primary bushings/terminals – the primary terminals are attached to the high voltage side of the transformer. Primary bushings can be in single or double bushing depending whether it is for line-to-neutral or line-to-line application. The basic construction of a primary bushing is made up of the conducting terminals and the ceramic insulator.
Secondary bushings/terminals – the secondary terminals are found perpendicular to the body of the distribution transformer. Some distribution transformers have two, three or four terminals depending on the preference of the user.
Cooling fins/radiators – Cooling fins serves as a heat dissipation device intended to reduce the temperature rise of the liquid insulation (oil). The mineral oil helps dissipate heat and protects the transformer from moisture, which will float on the surface of the oil.
Transformer KVA rating – is the visual indicator of the kva capacity of the distribution transformer designed to be seen from a far.
Pressure Relief Device – although not found in the illustration, pressure relief devices are usually found in a typical distribution transformer intended to release pressure build up once specified limit is reached.
Body Grounding Terminal – this is to have a physical ground connection from the transformer tank for safety purposes.
Distribution transformers normally have ratings less than 200 kVA,[2] although some national standards can allow for units up to 5000 kVA to be described as distribution transformers.
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Good one, thanks for the post. It contains useful information regarding Distribution Transformer.
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