What is current transformer burden?

What is current transformer burden?
In a current transformer (CT), burden refers to the total impedance (resistance and reactance) presented to the CT’s secondary winding by the connected measuring device (such as an ammeter, relay, or meter). It is typically expressed in volt-amperes (VA) at a specific secondary current (usually 1A or 5A) and may include the impedance of the connecting wires and instrument.
Load Components: The load consists of the impedance of connected devices (such as meters, protective relays, and wiring) that draw power from the CT’s secondary winding.
Burden Rating:
The CT’s rated maximum load is expressed in VA; for example, 10 VA indicates that the connected load should not exceed 10 VA.
If the load exceeds the CT’s rating, it can cause current measurement errors or protective failures, as the CT may not maintain its accuracy or properly step down the current.
The Importance of Proper Burden:
Load affects the accuracy of the CT. If the load is too high (i.e., the impedance of the connected device is too high), the CT will not provide accurate current conversion, resulting in incorrect measurements or protective relay failure. On the other hand, if the load is too low, the CT may be closer to saturation, which can also lead to inaccuracies.
Practical Considerations:
When installing coiled tubing, it is important to calculate the load of all connected equipment and ensure it is within the rated load range of the coiled tubing to achieve proper performance.

In summary, the load is the load applied to the secondary winding of the current transformer, and ensuring it is within the rated capacity of the CT is critical for accurate current measurement and safe operation.