Current transformers have been standardized at 5A secondary current and the voltage transformers at from 100V to 120V secondary voltage.

This Bushing type of transformer is comparable to the bar type, in that the secondary and core are located near the primary conductor. When the conductor passes through the bushing, it serves as the primary winding, and the core can be arranged by surrounding the core with an insulating bush.
      The transformer's secondary winding can be made into a circular core if not an annular one. This is linked to the high-voltage bushing in the switchgear, power transformers, circuit breakers, or generators.

The portable CTs' measuring current range is between 1000 and 1500 A. These transformers are primarily used to isolate measurement instruments from high-voltage circuits.

 These transformers are used to measure electricity in power plants, businesses, grid stations, and industrial control rooms for metering analyzing, and safeguarding applications,
These perform the role of safety protection and current limiting, to control, protect and operate relays and circuit breakers, etc

The Current transformer converts high current values to low and Potential transformer will convert high voltage values into low voltage both are called as instrument transformers.