Autotransformers

Autotransformer is an electrical transformer in which there is one winding, a portion of which is common to both the primary and the secondary circuits. An autotransformer uses common winding and offers no interference or disturbance isolation. The current in the high-voltage circuit flows through the series and common winding. The current in the low-voltage circuit flows through the common winding and adds vectorially to the current in the high-voltage circuit to give the common winding current. Thus, an electrical connection exists between high-voltage and low-voltage winding. Because of this sharing of parts of the winding, an autotransformer having the same kilovolt-ampere (kVA) output rating is generally smaller in weight and dimensions than a two-windings transformer. One possible disadvantage of autotransformers is that the windings are not insulated from each other and that the autotransformer provides no isolation of the primary and secondary circuits. Autotransformers are used in small sizes for intermittent-duty starting of motors called as motor starter. For this use the motor is connected for a short time to the common winding voltage

Standard configuration comes without a neutral lead. It is optional feature, but you can order if you require.