Current Transformer Ratio

The current transformer ratio is the ratio of the primary side current to the secondary side current, such as 500/5, 250/5, 100/5, 75/5, 50/5, 25/5, etc. For example, 500/5 means that when the primary current reaches 500A, the current induced on the secondary side is 5A, and the ratio of the two is the transformation ratio.

The secondary sides of the current transformers are all 5A. The transformation ratio of the current transformer is the primary side current divided by the secondary side current. Because of the current transformer, our ammeter can be made 5A. The current relay can also be made 5A. The current transformer is to turn a large current into a small current. So that the measurement, protection, signal, control and other secondary components can achieve uniform specifications.

A current transformer is an instrument that converts a large current on the primary side into a small current on the secondary side for measurement based on the principle of electromagnetic induction. A current transformer consists of a closed iron core and windings. Its primary side winding has few turns and is connected in the line of the current to be measured.

The transformation ratio is designed for different load sizes. When the primary current is large, the transformation ratio is large, and vice versa. But it must be appropriate. For example, the maximum value of the primary current exceeds 300A for a long time, and the 250/5 current transformer you choose will burn out due to overload. But the primary side current is small, if you choose a larger current transformer, the measurement will be inaccurate.