Difference between CT and PT, Current Transformer and Potential Transformer

       CT (Current Transformer)

    PT  (Potential Transformer)

1. The primary winding current in CT is independent of the secondary winding circuit condition.

The primary winding current is PT depends on secondary circuit burden.

2. In case of CT , it is connected in series with one line and a small voltage exist across its terminals, however CT carries the full line current.

In |PTs full line voltage is impressed upon its terminals.

3. The primary winding current and excitation of a CT vary over wide limits in normal operation.

In case of PT , it is under normal operation the line voltage is nearly constant and therefore the flux density and exciting current of a PT varies only over a restricted range .

4. The CT may be through as a series transformer under virtual short circuit conditions.

The PT may be considering as parallel transformer with its secondary winding operating under open circuit conditions.

6. The secondary of a C.T cannot be open during maintenance.

The secondary of  a P.T can be open circuited maintenance or during testing.

7. In case of CT primary current is independent of the secondary circuit condition.

In case of PT , its primary current is depend on secondary circuit condition.

8. It can be consider as a series transformer

It can be consider as a parallel transformer.

9. By the help of CT , a 5A ammeter can be measured higher current.  As like 400A.

With the help of PT , A 230 Voltmeter can be measured thousand volt. As like 11KV.

10.  CT is used for current measurement

PT is used for Voltage measurement