Ziegler ZiS 4.21B Current Transformer, is one of the cable and busbar primer low voltage current transformer type and is used for measuring current. A current transformer (CT) is used for measurement of alternating electric currents. Current transformers, are known as instrument transformers. When current in a circuit is too high to apply directly to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments. A current transformer isolates the measuring instruments from what may be very high voltage in the monitored circuit. Current transformers are commonly used in metering and protective relays in the electrical power industry.The secondary winding of current transformer has more rounds than primary winding. Ziegler Current Transformers or Ziegler CT's as they are better known are encased with polycarbonate housing . These are available for different ratings , VA burdens & Accuracy classes . with 21mm busbar hole dimension , Accuracy classes 0.5 , 1, 3 , burdens from 1 to 7.5 VA . Bornika is the exclusive representative of Ziegler company, in purchasing , sales , consulting and distribution of industrial equipment and transformers , including Measurement Current Tansformer(CT) , in low voltage.