What is meant by Rated burden of CT?
Burden of CT is defined as the volt ampere loading which is permissible without errors exceeding the limits for an assigned accuracy class. It is expressed as volt ampere (VA). In simple words, it is the load connected to CT secondary. CT burdens are specified as 10 VA, 15 VA, 20 VA, 30 VA.
What is burden in instrument transformer?
Burden is the small voltage drop across the reflected impedance of the secondary in the primary. Since the primary is normally one turn and the turns ratio is high and the secondary effectively shorted by a current instrument. it is a small but finite voltage.
What is reference value of rated secondary current of current transformer?
The rated secondary current is normally standardized at 1 or 5 amperes. For example, a 4000:5 CT secondary winding will supply an output current of 5 amperes when the primary winding current is 4000 amperes.
What is accuracy limit factor?
“Thus accuracy Limit Factor can be defined as the ratio of limiting primary current up to which accuracy of CT is maintained to the rated primary current.”
Why CT secondary never kept open?
If the primary circuit has current flowing the secondary circuit should never be opened. This can cause very high voltages to occur due to the Ampere-Turns of the primary that start magnetizing the core. This results in the core being saturated through a large portion of the cycle.