VPI Dry Type Transformer

Part I: Product Overview For 2500kVA, 33kV Dry-type Transformer

We adopt the advanced technology imported from Europe, patented technology, specialized software to optimize the design for 2500kVA, 33kV cast resin Dry Type Transformer. The core is made of cold-rolled grain-oriented silicon steel sheet which cut in step-lap by GEORG Germany TBA core cutting lines and laminated by the method of fifth-order step-by-step stacking technology, enabling the no-load performance of the core to improve greatly. The epoxy resin from American HUNTSMAN is adopted for the windings which casted in the vacuum resin casting machine imported from HEDRICH, Germany. The winding material ensures good permeability, no bubbles occur, which leads to minimum partial discharge. The HV and LV winding mate with each other tightly, which ensures solid strength of structure and capability to withstand short circuit and vibration. Under normal service condition, the service life of Dry type Transformer is 30 years. No crack will form on the surface of transformer winding due to temperature variation as long as the transformer runs under normal service condition.

Part II: Product Features

1. Low-noise & Low-loss:

a) Transformer noise comes from the core. The core is made of high quality cold-rolled grain-oriented silicon steel sheet. The lamination sheets are produced by automatic step-lap core lamination line from GEORG, Germany. 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 lowers 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 the amplitude and noise of components, while the surface of core is solidifying treated, which plays a role of sound proof.

2. Non-flammable, no pollution to environment

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 the composite materials resin used in dry-type transformer generate very little heat when in combustion (about 65ml/kg). The transformer has the feature of fire-retardant and self-extinguishing, so no arc will occur because of 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 soliditying 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 the normal conditions, when transformer under air natural cooling(AN) it can output 100% rated capacity continuously When transformer under air forced cooling (AF), its output capacity can be increased by 30% 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 transformer Temperature controller has function of temperature display and control of each phase. It will give off trip coil temperature is over limited. Under air forced cooling condition, the temperature controller can automatically start or stop fans according to the winding temperature. The temperature monitoring of windings and core, 4-20mA analog output or RS485 computer communication can be provided according to kinds of requests from clients to meet the need of modern electric power operation automation management.