Multi core current transformer structure principle and core grounding detection

The structure of the multi core current transformer is relatively simple, and consists of a primary winding, a secondary winding, a core, and a frame, a casing, and a terminal block insulated from each other. The working principle is basically the same as that of the transformer, the number of turns of the primary winding is less, and is directly connected in series in the power line. When the primary load current passes through the primary winding, the alternating magnetic flux generated generates a proportionally reduced secondary current. 

The secondary winding of the multi core current transformer has a large number of turns, and forms a closed loop in series with the secondary load of the current coil of the meter, the relay, the transmitter, etc., since the primary winding and the secondary winding have equal ampere-turns, The rated current of the multi core current transformer is smaller than that of the actual operation, and the secondary winding is close to the short-circuit state, which is equivalent to a short-circuiting transformer.

Multi core current transformer core multi-point grounding detection can be done in two ways, one is gas chromatography analysis. If the content of methane and ethylene in the gas is high, and the content of carbon monoxide and carbon dioxide gas is not much changed compared with the past, it may be due to overheating of the iron core due to multi-point grounding; when acetylene gas is present, the iron core has been Intermittent multi-point grounding occurs.

Another is to measure the current on the ground lead of the multi core current transformer core grounding bushing with a clamp-type ammeter. If the iron core is normally grounded, the current on the grounding wire is very small, which is milliampere level. When there is multi-point grounding, the main magnetic flux around the core is equivalent to the circulating current flowing through the short-circuiting ,, and its value is determined. The relative position of the fault point to the normal grounding point, that is, the amount of magnetic flux enclosed in the short-circuiting cymbal, can generally reach several tens of amps. This makes it possible to accurately determine whether the core has multiple ground faults.www.ctsensorducer.com