Knowledge 
How to Check the Knee Point voltage of the CT?
Release Time : 2020-11-08 View Count : 次The current transformer of PS class can be tested for whether or not the CT has the knee point voltage as per the manufacturer specifications. The test procedure is very simple and can be done if the variable voltage source is available.
Test Set-up:
Test Procedure for knee point Voltage calculation of CT :
Disconnect the CT from all external connection
Note down the knee point voltage of CT ( as per datasheet of the CT).
Apply 5-10 % voltage of the knee point voltage to the secondary of the CT by auto-transformer. Note down the secondary current.
Increase the voltage gradually to 20,30,40,50,60,70,80,90 % of the rated knee point of the CT and note down the secondary current.
Now increase the voltage to 100% of KPV and note down the current.
Increase the voltage above 110% of KPVand observe the increase in the secondary current. If the secondary current increase is 50% with an increase in this 10% voltage. The Knee point voltage of the CT is the voltage as per step No.5.
