Current transformers (CTs) are key components in electrical measurement and monitoring systems. But how do they work?
A current transformer steps down high currents in a circuit to a lower, manageable level, making it safe and easy to measure with standard instruments. For example:
A 100:1 ratio CT converts 1 amp in the primary to 10 mA in the secondary.
The current is then passed through a load resistor to produce a proportional voltage (100 mV in this case).
This proportionality allows precise current measurements without directly interfacing with high-current systems, ensuring safety and accuracy.
!! Why You Shouldn’t Leave CTs Open Circuit
If the secondary winding is left open while the primary is carrying current, the CT will attempt to maintain the current ratio. This can cause a very high voltage to develop across the open secondary, potentially damaging the CT and posing a safety hazard. Always connect a proper burden resistor or load to the CT’s secondary to avoid this risk.
Applications
CTs are widely used in energy meters, protection relays, and monitoring systems to measure current efficiently and safely.