Electrical Machines

Three phase Transformer Bank of Single phase Transformers: The different Three phase Transformer Bank of Single phase Transformers are namely, Delta/delta connection: The supply voltage provides only sinusoidal magnetizing current so that core flux is flat-topped; but the third-harmonic emfs induced (cophasal) cause circulating currents in deltas restoring the flux to almost sinusoidal. The third-harmonic […]

Three Phase Transformer Connections: In generation, transformation, transmission and utilization of electric energy it can be shown that it is economical to use the three-phase system rather than the single-phase. For Three Phase Transformer Connections, three single-phase transformers are needed. Two arrangements are possible: a bank of three single-phase transformers or a single three-phase transformer

Variable Frequency Transformer | Application: So far we have considered transformers which operate at fixed frequency (50 Hz). Their purpose is to transform electric power from one voltage level to another; their performance measures being high efficiency and low voltage regulation. Small transformers (usually iron-cored) are used for coupling purposes in electronic circuits for communication,

Autotransformer | Definition | Use of Auto transformer: So far two-winding transformers have been discussed wherein the windings are electrically isolated. When the primary and secondary windings are electrically connected so that a part of the winding is common to the two as shown in Fig. 3.35 (core is not shown here), the transformer is

Switching Transients in Transformer | Transformer Inrush Current: Switching Transients in Transformer – In the earlier discussion earlier steady-state operation was assumed so that v1 and Φ are both sinusoidal, Φ lagging v1 by 90° as shown once again in Fig. 3.33(a). The Φ – i0 relationship is shown in Fig. 3.33(b). The normal exciting current

Excitation Phenomenon in Transformer: It was stated already that the no-load current in a transformer is nonsinusoidal. The basic cause for this Excitation Phenomenon in Transformer, which lies in Transformer Hysteresis and Saturation non­linearities of the core material, will now be investigated; this can only be accomplished graphically. Assume that the voltage v1 applied to

Voltage Regulation Formula of Transformer: Voltage Regulation Formula – Constant voltage is the requirement of most domestic, commercial and industrial loads. It is, therefore, necessary that the output voltage of a transformer must stay within narrow limits as the load and its power factor vary. This requirement is more stringent in distribution transformers as these

Transformer Efficiency Formula: Power and distribution transformers are designed to operate under conditions of constant rms voltage and frequency and so the efficiency and voltage regulation are of prime importance. Transformer Efficiency Formula is the rated capacity of a transformer is defined as the product of rated voltage and full load current on the output