CLASSIFICATION OF DISTRIBUTION TRANSFORMERS IN AN ELECTRICAL DISTRIBUTION SYSTEMHow are distribution transformers being classified according to different parameters?
In dealing with distribution transformers, several parameters are always in consideration that describes the factors that a distribution transformer must have. Distribution transformers are classified into several different categories based on certain factors such as:
Type of Insulation used – distribution transformer insulation does not only ensures isolation of the transformer windings from other transformer parts (i.e. tank) but also serves as a coolant during rise of temperature. The transformer insulation can be liquid-immersed or dry-type. Liquid-immersed distribution transformers typically use oil to insulate the core and the windings. This oil can either be mineral or synthetic that should be non-flammable. Dry-type on the other hand uses gaseous or dry compound as an insulating medium.
Number of phases – depending on the nature of load that should be catered, a distribution transformer can be designed to serve either a single-phase or a three-phase load. Also, a single-phase transformer can also be used to serve a three-phase load by interconnecting 3-units of single-phase transformer or banked them to create a three-phase equivalent. However, a single unit three phase distribution transformer is also readily available if preferred by the utility or with the customer.
Voltage Class (for dry type) – The voltage class of a dry-type distribution transformer breaks down into two; low voltage distribution transformer or medium voltage distribution transformer. Voltage class of a distribution transformer depends on the desired secondary voltage while also considering the primary voltage where it would be connected. When specifying distribution transformers, manufacturers should know what voltage level a distribution transformer will be used.
Basic Impulse Insulation Level (BIL) - Outdoor electrical distribution systems are subject to lightning surges. Even if the lightning strikes the line some distance from the transformer, voltage surges can travel down the line and into the transformer. High voltage switches and circuit breakers can also create similar voltage surges when they are opened and closed. Both types of surges have steep wave fronts and can be very damaging to electrical equipment. To minimize the effects of these surges, the electrical system is protected by lighting arresters but they do not completely eliminate the surge from reaching the transformer. The basic impulse level (BIL) of the transformer measures its ability to withstand these surges. All 600 volt and below transformers are related 10 KV BIL. The 2400 and 4160 volt transformers are rated 25 KV BIL.
Transformer Location – the location of which the distribution transformer must be installed must also be considered. Indoor transformers are designed that this type of equipment must be protected from weather. An outdoor transformer has a construction designed to be weather resistant and suitable for varying weather service.
In dealing with distribution transformers, several parameters are always in consideration that describes the factors that a distribution transformer must have. Distribution transformers are classified into several different categories based on certain factors such as:
Type of Insulation used – distribution transformer insulation does not only ensures isolation of the transformer windings from other transformer parts (i.e. tank) but also serves as a coolant during rise of temperature. The transformer insulation can be liquid-immersed or dry-type. Liquid-immersed distribution transformers typically use oil to insulate the core and the windings. This oil can either be mineral or synthetic that should be non-flammable. Dry-type on the other hand uses gaseous or dry compound as an insulating medium.
Number of phases – depending on the nature of load that should be catered, a distribution transformer can be designed to serve either a single-phase or a three-phase load. Also, a single-phase transformer can also be used to serve a three-phase load by interconnecting 3-units of single-phase transformer or banked them to create a three-phase equivalent. However, a single unit three phase distribution transformer is also readily available if preferred by the utility or with the customer.
Voltage Class (for dry type) – The voltage class of a dry-type distribution transformer breaks down into two; low voltage distribution transformer or medium voltage distribution transformer. Voltage class of a distribution transformer depends on the desired secondary voltage while also considering the primary voltage where it would be connected. When specifying distribution transformers, manufacturers should know what voltage level a distribution transformer will be used.
Basic Impulse Insulation Level (BIL) - Outdoor electrical distribution systems are subject to lightning surges. Even if the lightning strikes the line some distance from the transformer, voltage surges can travel down the line and into the transformer. High voltage switches and circuit breakers can also create similar voltage surges when they are opened and closed. Both types of surges have steep wave fronts and can be very damaging to electrical equipment. To minimize the effects of these surges, the electrical system is protected by lighting arresters but they do not completely eliminate the surge from reaching the transformer. The basic impulse level (BIL) of the transformer measures its ability to withstand these surges. All 600 volt and below transformers are related 10 KV BIL. The 2400 and 4160 volt transformers are rated 25 KV BIL.
Transformer Location – the location of which the distribution transformer must be installed must also be considered. Indoor transformers are designed that this type of equipment must be protected from weather. An outdoor transformer has a construction designed to be weather resistant and suitable for varying weather service.
Sri Sai Ram Power Controls as a manufacturer of Power Transformers, Distribution Transformers, Furnace Transformers and Dry type Transformers has been part of Transformer Industry in India.
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Thanks for sharing knowledge of transformers. I am working in a company of Transformer Manufacturer In Jaipur where I always see the transformers around me. Always curious to know about them.
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