How to confirm the saturation of current transformer?

- Nov 16, 2020-

In order to study the working characteristics of the current transformer and determine whether it will saturate and affect the correctness of the protection operation when protecting the external fault from large currents, some test methods can be used to test. The following editor will briefly introduce these measures. Obviously, the direct test method is to bear the actual load on the secondary side, apply current from the primary side, and observe the secondary current to find the saturation point of the current transformer. However, for protection-level current transformers, the saturation point may exceed 15 to 20 times the rated current. When the current transformer becomes larger, it may be difficult to test in the field. In addition, the saturation point of the current transformer can also be measured through the volt-ampere characteristic test.

As mentioned earlier, the saturation of the current transformer is the saturation current of the current transformer calculated due to the excessive magnetic flux density of the iron core. The test method of volt-ampere characteristics is: the original side is disconnected, the current passes through the secondary side, and the voltage drop on the secondary side winding is measured. Since the primary side of the current transformer is open, the primary side current has no demagnetization effect, and the iron core is easily saturated at a small current. Therefore, the volt-ampere characteristic test does not need to increase the large current, which is relatively easy to implement in the field.