What is the meaning of burden in relay?

The total resistance of the secondary circuit of CT known as a burden is the sum of resistances of CT secondary winding,connecting wires(lead resistance) and the resistance of the relay/meter.

What is the value of the relay burden?

Relay burden = 2 For 20 times rated secondary current, i.e., 100A Secondary voltage = 100 x (2 + 0.61) = 261 Volts which is less than knee point of the CT.

What is the meaning of burden in electrical?

The burden is the termination impedance of the measuring instrument. All instruments that use a current transformer to measure line current must terminate the CT with a resistance (impedance in same case which means there is some inductance involved). A CT supplier should be given the burden when ordering.

How do you calculate burden value?

Burden for Metering type CT = Total Burden of Meters (Digital/Analog Ammeter, Voltmeter, Power Meter, MFM, Transducer) which are in series with CT + The total VA of the Cables connecting CT and the Meters. Cable VA = (2L x R x I^2). Cable VA= 5^2 x 0.02 x 2 x 2=2VA .

What is burden test for CT?

The burden test is performed to verify that the CT is capable of supplying a known current into a known burden while maintaining its stated accuracy. A burden test is typically performed at full rated secondary current value (ex. 5A or 1A).

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.

How is burden of PT calculated?

If a PT has a marked ratio of 480V/120V (ratio of 4), but the actual ratio is 480V/122V(ratio of 3.934), then RCF can be computed as 3.934/4 = 0.9836. Multiplying the actual secondary voltage (122V in this case) by the RCF (0.9836) yields the corrected output (122*0.9836=120V).