Difference Between Current Transformer (CT) & Potential Transformer (PT)

Comparison Chart

Basis for Comparison	Current Transformer	Potential Transformer
Definition	Transform the current from high value to low value.	Transform the voltage from high value to the low value.
Circuit Symbol
Core	Usually built up with lamination of silicon steel.	It is made up of with high-quality steel operating at low flux densities
Primary Winding	It carries the current which is to be measured	It carries the voltage which is to be measured.
Secondary Winding	It is connected to the current winding of the instrument.	It is connected to the meter or instrument.
Connection	Connected in series with the instrument	Connected in parallel with the instrument.
Primary Circuit	Has a small number of turns	Has a large number of turns
Secondary Circuit	Has a large number of turns and cannot be an open circuit.	Has a small number of turns and can be an open circuit.
Range	5A or 1A	110v
Transformation Ratio	High	Low
Burden	Does not depends on the secondary burden	Depends on the secondary burden
Input	Constant current	Constant Voltage
Full line current	The primary winding consists of the full line current.	The primary winding consists of the full line voltage.
Types	Two types ( Wound and Closed Core )	Two types (Electromagnetic and Capacitor voltage)
Impedance	Low	High
Applications	Measuring current and power, monitoring the power grid operation, for operating protective relay,	Measurement, power source, operating protective relay,