The safe operation of dry-type transformers and service life, a large transformer winding insulation depends on the safety and reliability. Winding temperature exceeds the temperature of the insulation damage to insulation resistance, the transformer does not work is one of the main transformer operating temperature monitoring alarm control is very, today on the TTC-300 series temperature control system to make a profile.
(1) fan automatic control: embedded in low-voltage winding through the hottest temperature at the thermal resistance of the Pt100 temperature measuring signal obtained. Transformer load increases, the operating temperature rise, when the winding temperature reaches 110 ℃, the system automatically starts the cooling fan; when the winding temperature as low as 90 ℃, the system automatically stops the fan.
(2) over-temperature alarm trip: embedded in low-voltage winding through the PTC thermistor temperature resistance non-linear acquisition winding or core temperature signal. When the transformer winding temperature continues to rise, if reached 155 ℃, the system output over-temperature alarm signal; If the temperature continues to rise up to 170 ℃, the transformer can no longer continue to run, the secondary protection circuit required to transport over-temperature trip signal, the transformer should be quick trip.
(3) Temperature display system: embedded in low-voltage winding through the Pt100 thermistor measured temperature values ??obtained, directly showing the winding temperature (maximum three-phase inspection and display, and record a record high temperature), can be the maximum temperature to 4 ~ 20mA analog output, For transmission to a remote (distance up to 1200m) computers can be equipped with a computer interface, a transmitter can monitor up to 31 transformers. System over-temperature alarm and trip can also be Pt100 thermal sensor resistance signal action to further improve the temperature control to protect system reliability.
Way of dry-type transformer protection
Characteristics and based on the environment protection, dry-type transformers can choose a different shell. IP20 enclosure protection is usually used to prevent solid foreign objects greater than 12mm in diameter and rats, snakes, cats, birds and other small animals, causing a short circuit power outages and other serious failure to live parts to provide a safe barrier. If the transformer shall be installed on outdoor, IP23 protective shell can be used, in addition to the IP20 protection, but also to prevent the vertical angle of 60 ° or less of water droplets into. However, the cooling capacity of the transformer IP23 housing will decline, the choice of when to pay attention to reduce its operating capacity.
Dry-type transformer cooling
Dry-type transformer cooling divided into natural air cooling (AN) and forced air cooling (AF). Natural air cooling, the transformer can be rated capacity under long-term continuous operation. Forced air cooling, the transformer output capacity can be increased by 50%. For intermittent overload operation, accident or emergency overload operation; overload when the load loss and impedance voltage larger increase in non-economic to run, so it should not be in the long run a continuous overload.
