The current transformer’s wiring accuracy is very important, because in the secondary circuit, weather the current transformer wiring is appropriate is the basis for weather the secondary circuit appropriate. During power installation engineering projects, the key content is electrical debugging work, especially the secondary circuit inspection, which related to the precise measurement, maintenance, communication etc functions.

A) . Common Wring Standard

1. The transformer secondary side don’t allow with open circuit. Secondary open circuit easy to cause serious problem such as: the coils overheated to damages transformer; too many turns of the secondary winding will induce the high voltage risk of the electromagnetic coil, which will seriously endanger personal safety and safety performance of industrial equipment.

2. The high voltage current transformer secondary side should be grounded. Because if transformer primary side is high voltage, when due to the insulating sleeve destruction the high voltage passed between the primary & secondary magnetic electromagnetic coils , the high voltage will be embedded into the low voltage. Once the secondary magnetic electromagnetic coils is grounded at one point, the high voltage will be introduced. In meantime, please notice that the current transformer’s secondary circuit allows one point to be grounded only, more grounding may cause current shunting&damage the application. However, for low voltage current transformer secondary side should not be grounded, because working voltage is relatively low, the insulation sleeve between the primary & secondary magnet electromagnetic coils has a large degree of desire, resulting in a small probability of passing through the primary&secondary.

3. The current transformer cannot insert reversely of precise measurement level & maintenance level. As we know, the thickness of design scheme of the winding inductance coil for accurate measurement and maintenance are not the same, once inserted,measuring accuracy will reduce; reduce short-circuit faults easily; making relay protection inflexible & damaging instrument panel.

4. Since the current transformer’s secondary winding cannot be opened, the windings which are not necessary should be wired as much as possible. However, for the current transformer with many tapes, the unnecessary taps can't be wired & should be empty, otherwise, it would damage the application tap’s measurement accuracy.

5. While connecting the measurement and verification windings of Current Transformers and the relay protection windings involving orientation, request grasp two points to establish the connection. Look at the ct’s installation location firstly, and then according to the winding function or relay protection type, above two points can be used to re-establish the current transformer wiring.