Low Tension Power Transformers
- SINGLE PHASE DOUBLE WOUND TRANSFORMERS :
As stated before, these are made in natural air cooled construction or natural oil cooled construction. Extra off-load taps can be provided on request. The capacity of the transformer at the tap will be proportionately low corresponding to the tap voltage. The declared capacity will hold good only for the highest voltages on both input and output, unless the taps are specified as full capacity taps.
- THREE PHASE DOUBLE WOUND TRANSFORMERS :
These transformers are generally manufactured in Delta/Star or Star/Delta connections. However, transformers can also be supplied suitable for Delta/Delta or Star/Star or Open/Open connections, on request against specific requirements , enquiries or direct orders should clearly state the voltage and connection on the primary and secondary and whether the voltages are between phases or between phase and neutral. Extra off-load taps can be provided at extra cost. The capacity of the transformers at the tap will be proportionately reduced corresponding to the tap voltage. The declared capacity will hold good only for the highest voltage on both input and output unless the taps are specified as full capacity taps.
- THREE PHASE TO SINGLE PHASE DOUBLE WOUND TRANSFORMERS :
These transformers are very widely used where large single phase power is required. These are wound as open delta on the three phase input side and the windings on the secondary are connected in series for single phase output. This type construction gives on unbalance in the supply current. E.g. a 10 KVA three phase to single phase transformer will have a current distribution as i) Phase A : 14.5 A, ii) Phase B : 29 A and iii) Phase C : 14.5 A, approximately when the supply voltage is 400 volts nominal.
However, this unbalance is less severe than when a single phase load is connected between a phase and a neutral or between phase to phase
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