1. Dry-type transformer temperature control system The safe operation and service life of dry-type transformers depend largely on the safety and reliability of transformer winding insulation. The winding temperature exceeds the insulation withstand temperature and the insulation is destroyed, which is one of the main reasons for the transformer not working properly. Therefore, it is very important to monitor the operating temperature of the transformer and its alarm control. This is the TTC-300 series temperature control system. A brief introduction.
(1) Fan automatic control: The temperature signal is measured by the PT100 thermal temperature measuring resistor embedded in the hottest part of the low voltage winding. The transformer load increases and the operating temperature rises. When the winding temperature reaches 110 °C, the system automatically starts the fan cooling; when the winding temperature is as low as 90 °C, the system automatically stops the fan.
(2) Over-temperature alarm, trip: The winding or core temperature signal is collected by a PTC nonlinear thermal temperature measuring resistor embedded in the low-voltage winding. When the transformer winding temperature continues to rise, if the temperature reaches 155 °C, the system outputs an over-temperature alarm signal; if the temperature continues to rise to 170 °C, the transformer can no longer continue to operate, and the over-temperature trip signal must be sent to the secondary protection circuit. Quickly trip.
(3) Temperature display system: The temperature change value is measured by the PT100 thermistor embedded in the low voltage winding, and the temperature of each phase winding is directly displayed (three-phase inspection and maximum value display, and the historical maximum temperature can be recorded). The maximum temperature is output in 4~20MA analog quantity. If it needs to be transmitted to a remote computer (distance up to 1200M), it can be equipped with a computer interface, 1 transmitter, and up to 31 transformers can be monitored at the same time. The system's over-temperature alarm and trip can also be acted upon by the PT100 thermal sensing resistor signal to further improve the reliability of the temperature control protection system.
2, the dry transformer protection method According to the use of environmental characteristics and protection requirements, dry transformers can choose different shells. The IP20 protective casing is usually used to prevent solid foreign objects larger than 12mm in diameter and small animals such as rats, snakes, cats, and birds, which cause malignant faults such as short-circuit power failure and provide a safety barrier for the live parts. If the transformer needs to be installed outdoors, the IP23 protective casing can be used. In addition to the above IP20 protection function, it can prevent water droplets from entering within 60° of the vertical line. However, the IP23 housing will reduce the cooling capacity of the transformer, and pay attention to the reduction of its operating capacity when selecting.
3. Drying transformer cooling mode The dry transformer cooling method is divided into natural air cooling (AN) and forced air cooling (AF). When naturally air cooled, the transformer can run continuously for a long time under rated capacity. When forced air cooling, the transformer output capacity can be increased by 50%. It is suitable for intermittent overload operation or emergency accident overload operation; due to overload and load voltage increase during overload, it is in non-economic operation state, so it should not be in continuous continuous overload operation.
4. Overload capability of dry-type transformer The overload capacity of dry-type transformer is related to the ambient temperature, the load condition before overload (starting load), the insulation heat dissipation of the transformer and the heating time constant. If necessary, it can be obtained from the manufacturer. Dry change overload curve.
How to use its overload capacity? The author proposes two points for reference:
(1) Selecting the calculation of transformer capacity can be appropriately reduced: fully consider the possibility of short-term impact overload of some steel rolling, welding and other equipment - try to use the strong overload capacity of dry-type transformer to reduce the transformer capacity; Some places with uneven load, such as residential areas for night lighting, cultural and recreational facilities, and air-conditioning and daylight-based shopping malls, can make full use of their overload capacity, appropriately reduce the transformer capacity and make it the main running time. At full load or short time overload.
(2) It can reduce the spare capacity or the number of units: In some places, the spare coefficient of the transformer is required to be high, which makes the transformer of the project optional and has a large number of units. The overload capacity of the dry change can be compressed when considering the spare capacity; it can also be reduced when determining the number of spares. When the transformer is in overload operation, be sure to monitor its operating temperature: if the temperature rises to 155 ° C (with alarms issued), load shedding measures should be taken (minus some secondary loads) to ensure safe power supply to the main load.
5, dry-type transformer low-voltage outlet mode and its interface with dry-type transformers because there is no oil, there is no fire, explosion, pollution and other issues, so electrical specifications, procedures, etc. do not require dry-type transformers in a separate room. In particular, the new SC(B)9 series has reduced losses and noise to new levels, creating conditions for transformers and low-voltage screens to be placed in the same distribution room. In order to adapt to this situation, Shunde Special Transformer Factory introduced the SC(B)8 series new products in 1996, and first introduced the standard closed busbars and standard horizontal side outlets to customers in its "Dry Transformer Technical Manual". Standard low-voltage side outlets and other low-voltage outlets. In the "SC(B)9 Series Dry-Type Transformer Technical Manual" published in 1998, the above-mentioned low-voltage outlets have been affirmed and further improved, and are widely welcomed by customers and design organizations. . In recent years, the design unit has gradually become familiar with and selected, and is briefly introduced here.
(1) Fan automatic control: The temperature signal is measured by the PT100 thermal temperature measuring resistor embedded in the hottest part of the low voltage winding. The transformer load increases and the operating temperature rises. When the winding temperature reaches 110 °C, the system automatically starts the fan cooling; when the winding temperature is as low as 90 °C, the system automatically stops the fan.
(2) Over-temperature alarm, trip: The winding or core temperature signal is collected by a PTC nonlinear thermal temperature measuring resistor embedded in the low-voltage winding. When the transformer winding temperature continues to rise, if the temperature reaches 155 °C, the system outputs an over-temperature alarm signal; if the temperature continues to rise to 170 °C, the transformer can no longer continue to operate, and the over-temperature trip signal must be sent to the secondary protection circuit. Quickly trip.
(3) Temperature display system: The temperature change value is measured by the PT100 thermistor embedded in the low voltage winding, and the temperature of each phase winding is directly displayed (three-phase inspection and maximum value display, and the historical maximum temperature can be recorded). The maximum temperature is output in 4~20MA analog quantity. If it needs to be transmitted to a remote computer (distance up to 1200M), it can be equipped with a computer interface, 1 transmitter, and up to 31 transformers can be monitored at the same time. The system's over-temperature alarm and trip can also be acted upon by the PT100 thermal sensing resistor signal to further improve the reliability of the temperature control protection system.
2, the dry transformer protection method According to the use of environmental characteristics and protection requirements, dry transformers can choose different shells. The IP20 protective casing is usually used to prevent solid foreign objects larger than 12mm in diameter and small animals such as rats, snakes, cats, and birds, which cause malignant faults such as short-circuit power failure and provide a safety barrier for the live parts. If the transformer needs to be installed outdoors, the IP23 protective casing can be used. In addition to the above IP20 protection function, it can prevent water droplets from entering within 60° of the vertical line. However, the IP23 housing will reduce the cooling capacity of the transformer, and pay attention to the reduction of its operating capacity when selecting.
3. Drying transformer cooling mode The dry transformer cooling method is divided into natural air cooling (AN) and forced air cooling (AF). When naturally air cooled, the transformer can run continuously for a long time under rated capacity. When forced air cooling, the transformer output capacity can be increased by 50%. It is suitable for intermittent overload operation or emergency accident overload operation; due to overload and load voltage increase during overload, it is in non-economic operation state, so it should not be in continuous continuous overload operation.
4. Overload capability of dry-type transformer The overload capacity of dry-type transformer is related to the ambient temperature, the load condition before overload (starting load), the insulation heat dissipation of the transformer and the heating time constant. If necessary, it can be obtained from the manufacturer. Dry change overload curve.
How to use its overload capacity? The author proposes two points for reference:
(1) Selecting the calculation of transformer capacity can be appropriately reduced: fully consider the possibility of short-term impact overload of some steel rolling, welding and other equipment - try to use the strong overload capacity of dry-type transformer to reduce the transformer capacity; Some places with uneven load, such as residential areas for night lighting, cultural and recreational facilities, and air-conditioning and daylight-based shopping malls, can make full use of their overload capacity, appropriately reduce the transformer capacity and make it the main running time. At full load or short time overload.
(2) It can reduce the spare capacity or the number of units: In some places, the spare coefficient of the transformer is required to be high, which makes the transformer of the project optional and has a large number of units. The overload capacity of the dry change can be compressed when considering the spare capacity; it can also be reduced when determining the number of spares. When the transformer is in overload operation, be sure to monitor its operating temperature: if the temperature rises to 155 ° C (with alarms issued), load shedding measures should be taken (minus some secondary loads) to ensure safe power supply to the main load.
5, dry-type transformer low-voltage outlet mode and its interface with dry-type transformers because there is no oil, there is no fire, explosion, pollution and other issues, so electrical specifications, procedures, etc. do not require dry-type transformers in a separate room. In particular, the new SC(B)9 series has reduced losses and noise to new levels, creating conditions for transformers and low-voltage screens to be placed in the same distribution room. In order to adapt to this situation, Shunde Special Transformer Factory introduced the SC(B)8 series new products in 1996, and first introduced the standard closed busbars and standard horizontal side outlets to customers in its "Dry Transformer Technical Manual". Standard low-voltage side outlets and other low-voltage outlets. In the "SC(B)9 Series Dry-Type Transformer Technical Manual" published in 1998, the above-mentioned low-voltage outlets have been affirmed and further improved, and are widely welcomed by customers and design organizations. . In recent years, the design unit has gradually become familiar with and selected, and is briefly introduced here.
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