We adopt the state-of-art technology and professional software to optimize the design for 2500kVA, 20kV cast resin Dry Type Transformer. The magnetic core is made from cold-roller grain-oriented silicon steel which has a miter step joint to ensure optimum performance and minimum sound levels by using step lap technology. The magnetic steel is cut to length sequentially and automatically stacked. This ensures dimensional accuracy and single sheet interlacing within the full stack.
We select American HUNTSMAN resin as our main casting resin material which is casted in vacuum casting vessel. Our casting process achieves good permeability without bubbles inside and guarantees minimum partial discharge. The HV and LV windings fix with each other tightly, which ensures solid strength of structure and improves capability to withstand short circuit and vibration. Under normal service condition, the service life of Dry type Transformer can be more than 30 years. No crack will occur on surface of transformer winding from temperature variation, as long as transformer operates under normal service condition.
1. Lower-noise & Lower-loss:
a) Transformer noise comes from the core. The magnetic steel is cut to length sequentially and automatically stacked. This ensures dimensional accuracy and single sheet interlacing within the full stack. Such method improves the distribution of magnetic circuit and result in lowering the noise level.
b) The transformer adopts the high quality silicon steel sheet whose low magnetic density stays away from its saturation point and decreases the harmonic in the core, and reduces the noise and no-load loss of the transformer.
c) All parts used for clamping apply silicon rubber and flexible elements as buffers, in order to reduce amplitude and noise of components, while the surface of core is solidifying treated.
2. Non-flammable, Environmental-Friendly
a) Solid electrical insulation composed of high quality resin could provide with high electrical strength (breakdown voltage≥34kv/mm) and partial discharge can be controlled in the range of ≤5pC.
b) As composite materials resin used in dry-type transformer generate little heat when in combustion (about 65ml/kg). Our transformer has the feature of fire-retardant and self-extinguishing, therefore, no arc will occur due to short circuit and no toxic or harmful smoke or dusts will be produced at high temperature.
c) The coil is free of moisture and core is solidifying treated. The transformer can be in continuous reliable operation in circumstance of 100% relative humidity, and no need to interrupt its service to eliminate moisture.
d) Dry type transformer also has great advantages such as strong overload capability, good thermal stability, compact size, light weight, easy installation; maintenance-free and so on. Dry type transformer covers wide fields of high-rise buildings, commercial centers, airports, stations, ports, subway, factories and underground power distribution stations.
3. Cooling Method:
Cooling method of dry type transformer is divided into air natural cooling (AN) and air forced cooling (AF). Under AN conditions, it is designed to output 100% rated capacity continuously. When transformer is under AF mode, its output capacity can be increased by 50%, which is suitable for all kinds of emergency, overload or intermittent load operation.
4. Temperature Control System:
Temperature control system consists of temperature controller and Pt100 temperature sensor located at the hottest point of winding. Transformer Temperature controller has function of temperature display and control of each phase. The temperature controller can automatically start or stop fans according to the winding temperature.