How to ground the miniature current transformer

- Aug 19, 2020-

It is reported that there is a wide range of synergies in the development and production management of miniature current transformers to further enhance the core competitiveness of the current transformer market at low prices in the field of disconnectors. All along, everyone is also interested in the question "How to ground the current transformer?", hoping to learn more about the current transformer.

In order to prevent the insulation breakdown between the primary and secondary windings of the current transformer, the high voltage on the primary side enters the secondary test, which endangers the equipment and personal safety. One end of the second measurement must be reliably grounded.

One end (S2) of the current transformer side is grounded to prevent the high voltage on the primary side from entering the secondary side when the insulation between the primary and secondary windings breaks down, endangering personal and equipment safety.

The current transformer enclosure and secondary response are grounded. The principle of secondary circuit grounding is one-point grounding. It is usually used to ground at the "-" end. Two or more points are not allowed to be grounded to avoid loops or short circuits.

Two or three current transformers are commonly used in a three-phase circuit to form a group. In actual use, the secondary circuits of 3 (or 2) current transformers are often connected into a star, incomplete star, two-phase differential or three-phase delta according to a certain wiring method. At this time, special attention should be paid: one point of grounding is used on the entire secondary circuit. It is customary to choose the neutral point or common terminal of the second circuit.

If the current transformer power cable is running through (L1 incoming line), the K2 of the three transformers is grounded in series (that is, the 3, 6, and 9 binding posts at the end of the meter are grounded in series), otherwise the K1 is grounded in series.

Normally, the probability of breakdown between the first and second times is poor, almost impossible, because the wire is passed through the middle hole, usually the charged wire does not contact the CT surface, the medium in the middle is air, and everyone knows that the resistance of air is infinite of!

But there is a possibility that it may cause a breakdown, that is, the secondary ground of the same name of the lightning wave is to protect the instrument and personal safety and cause losses. Once it is not grounded!