GEAFOL-Cast-Resin Transformers Planning Guidelines

Contents GEAFOL - for the highest requirements on location 4 Basic data for planning 5 Measures for fire protection according to DIN EN 61936-1 6 Classification according to the Ecodesign Directive 2009/125/EC 7 Special installation conditions 8 Protection against accidental contact 8 Connection of the high-voltage side 9 Connection of the HV side using plug-type connectors 9 High-voltage tappings 9 Connection of the low-voltage side 9 Connection of earthing and short-circuiting devices 9

Temperature monitoring with PTC thermistor 10 Transformer: Additional air cooling Efficiency of additional forced-air cooling 11 Ventilation of the Transformer Room 12 Calculation the heat losses in the room 12 Calculation the heat dissipation 12 Qv1: Heat dissipation by natural air circulation 12 Qv2: Heat dissipation through the walls and ceiling 13 Qv3: Heat dissipation by forced-air circulation 14 Room ventilation fans 14 Criteria for choice of room ventilation fans 14 Rating of the room ventilation fan 14 pr: Pressure difference due to flow 15 pb: Pressure difference due to acceleration...

GEAFOL – for the Most Stringent Local Conditions Easy to Integrate Anywhere GEAFOL® cast-resin dry-type transformers are the ideal solution wherever high load densities necessitate provision of power sources close to the load. They give designers the necessary freedom of action, since they facilitate the economic implementation of network concepts, because they are environmentally friendly and safe, and because they allow installation of power sources close to the load without the need for special rooms and precautions. These are aspects which predestinate these distribution transformers for...

All the technical data apply to GEAFOL cast-resin dry-type transformers with the following features: ■ Installation in enclosed electrical operating area in accordance with IEC61936-1 (DIN EN 61936) The data also generally apply to ■ liquid-immersed transformers in terms of "water conservation and fire protection measures and measures for preservation of functional integrity" in addition to those for "Ventilation" and "Noise" Our GEAFOL transformers meet the requirements of all relevant national, European and international standards (order-related). ■ EN 50588-1 medium voltage transformators...

InstallationRequirements GEAFOL transformers present the lowest requirements for the point of installation. These are determined by the regulations concerning fire protection and protection from leakage losses according to IEC 61936-1 (DIN EN 61936-1). The requirements of these regulations (from 2011) are compared below for transformers of different design. Measures for fire protection according to DIN EN 61936-1 (VDE 0101-1), simplified overview

Classification according to IEC 60076-11 This standard defines environment, climate and fire classes and in consequence thereof takes into account varying operating conditions existing at the point of installation. The climate class takes the lowest ambient temperature into account. Class C1: Indoor installation not under -5 °C Class C2: Outdoor installation down to -25 °C The climate class is thus also a measure for the fracture toughness of the cast-resin compound. The environment class takes air humidity, condensation and pollution into account. Class E0: No condensation, negligible pollution...

Minimum clearances around GEA-FOL transformers with safety edge (1) Temperature of the cooling air Transformers are designed in accordance with the applicable standards for the following cooling air values: ■ 30 °C monthly average of the hottest month If operated normally, the transformer should attain its expected lifetime consumption. In particular, the average annual temperature and the load significantly affect the lifetime consumption. Environment temperatures differing from the annual average have an effect on the system's load capacity. (Table 1). Extreme local conditions must be taken...

Fig. 3: Variable termination facility, e.g. at the delta-connected HV side Connection System Practice-oriented options for connection of the highvoltage and the low-voltage side are a distinguishing feature of the flexible connection philosophy of GEAFOL transformers. High-voltage tappings The HV tappings allow matching to local network conditions. The desired tapping can be selected by means of connection straps and screwed connections. Connection of the high-voltage side In the standard design the HV connection of the transformer is at the top coil connection, connection at the bottom is available...

Temperature Monitoring The PTC thermistor sensors function as resistances. When the response temperature is reached, a step-change in resistance occurs and the changeover contact in the tripping device is operated. As soon as the temperature falls below the response temperature by approx. 3 K, the relay coil in the tripping device is once more fully energized and the changeover contact returns to its original position. When two systems are employed for temperature super vision, one is connected to provide alarm signalling and the other tripping. The rated response temperatures of both systems...

Fig. 7: Attachment of centrifugal flow fans to GEAFOL transformers Additional Forced-Air Cooling to Increase the Transformer Power Rating The output rating of GEAFOL transformers up to 3,150 kVA with degree of protection IP 00 can be increased up to 50 % as a result of mounting centrifugal-flow fans. For example, the continuous power rating of a 1,000 kVA transformer can be increased to 1,500 kVA using this efficient method of forced cooling without exceeding the permissible winding temperatures (Fig. 7). The rating is then given on the rating plate as rated output: 1,000 kVA with type of cooling...

Ventilation of the Transformer Room Heat losses inevitably occur during operation of transformers. These losses must be dissipated from the transformer room. The first priority is thus investigation of whether natural ventilation is feasible. In cases where this is insufficient, installation of mechanical ventilation (forced-air ventilation) must be considered. Hints for the following are given below: Calculations for simple systems for natural and forced ventilation Diagrams and worked examples for dimensioning of ventilation systems Efficient specimen ventilation systems Assumptions The ambient...