Dry-type transformerThe safe operation and service life depend largely on the safety and reliability of the transformer winding insulation. The insulation damage caused by the winding temperature exceeding the insulation withstand temperature is one of the main reasons why the transformer cannot work normally, so it is very important to monitor the operating temperature of the transformer and control its alarm.

(1) Automatic control of the fan: The temperature signal is measured by the Pt100 thermistor embedded in the heating part of the low-voltage winding. When the transformer load increases, the operating temperature rises, and the winding temperature reaches 110, the system automatically starts the fan to cool down; when the winding temperature is as low as 90, the system automatically stops the fan.

Over-temperature alarm and trip: The built-in PTC nonlinear thermistor of the low-voltage winding is used to collect the temperature signal of the winding or iron core. When the temperature of the transformer winding continues to rise, if it reaches 155, the system will output an over-temperature alarm signal; if the temperature continues to rise to 170, the transformer cannot continue to run, an over-temperature trip signal must be sent to the secondary protection circuit, and the transformer should trip quickly.

Temperature display system: low-voltage winding embedded Pt100 thermistor to measure the temperature change value, directly display the winding temperature of each phase, and can output a higher temperature of 4 ~ 20mA analog quantity, if necessary, can be transmitted to a remote computer (distance up to 1200m).

Dry-type transformer protection mode

IP20 protective sleeve is usually used to prevent solid foreign objects with a diameter greater than 12mm and small animals such as rats, snakes, cats, birds, etc. from entering, causing short circuits, power outages and other malignant faults, and providing a safety barrier for live parts. If the transformer needs to be installed outdoors, IP23 protective enclosure can be selected. In addition to the above IP20 protection function, it can also prevent water droplets from falling within 60 degrees of the vertical line. However, the IP23 enclosure will reduce the cooling capacity of the transformer, so pay attention to the reduction of its operating capacity when selecting.

The overload capacity of dry-type transformer is related to the ambient temperature, the load before overload (initial load), the insulation heat dissipation and heating time constant of the transformer. If necessary, the overload curve of the dry transformer can be obtained from the manufacturer.

How to take advantage of its overload capacity?

When calculating the transformer capacity, it can be appropriately reduced: fully consider the possibility of short-term impact overload of some coil welding equipment; try to use the characteristics of strong overload capacity of dry-type transformers to reduce transformer capacity; for some places with uneven load, such as residential areas Mainly for night lighting, cultural and entertainment facilities, shopping malls mainly for air conditioning and daytime lighting. It is possible to make full use of its overload capacity, appropriately reduce the capacity of the transformer, so that its main running time is in full load or short-term overload state.