Precautions for the use of Electrical Current Transformer

(1) The secondary side of the Electrical Current Transformer cannot be opened during operation. Electrical Current Transformer Under normal operating conditions, the secondary magnetomotive force is similar in size to the primary magnetomotive force, but in the opposite direction, that is, the secondary magnetomotive force has a strong demagnetization effect on the primary magnetomotive force, so the synthesized magnetic flux is very high. Small, the value of the secondary electromotive force does not exceed tens of volts at most. When the secondary side open circuit is formed due to loose current lead joints, severe corrosion of the terminal gaskets caused by moisture in the outdoor terminal box, etc., the Electrical Current Transformer changes from a normal short-circuit operation condition to an open circuit operation condition, secondary current and secondary magnetism When the potential is zero, the primary magnetomotive force remains unchanged and all used for excitation. The magnetomotive force of the excitation increases sharply from I0N1, which has a small normal value, to I1N1, which makes the magnetic flux in the iron core increase sharply and reach fullness, and the magnetic flux waveform is distorted. Flat top wave. Since the induced electromotive force of the secondary winding is directly proportional to the rate of change of the magnetic flux, the secondary winding will induce a high peak wave electromotive force at the instant when the magnetic passes through zero, and its peak value can reach thousands of volts or even tens of thousands of volts, endangering workers Safety and insulation of secondary equipment. And due to the sharp increase in the magnetic flux of the iron core, the loss of the iron core increases, resulting in severe heat generation and even burning of the Electrical Current Transformer. In addition, the open circuit of the secondary side will also cause a large residual magnetism in the iron core, which will deteriorate the characteristics of the transformer. Therefore, when there is current in the primary winding of the Electrical Current Transformer, the secondary side does not allow an open circuit. If you want to remove the appearance or relay related to the Electrical Current Transformer during operation, it is necessary to short-circuit the secondary circuit with a wire or short-circuit connecting piece to prevent open circuit. When there is an open circuit, the electrical current transformer iron core has large electromagnetic oscillation, abnormal noise, iron core heating, abnormal smell or smoke, the secondary terminal thread may discharge, ignite, and the differential maintenance circuit TA disconnection signal alarm, related The indication of the ammeter, power meter, and electric energy meter is reduced or zero. When an open circuit on the secondary side is found, the operator should stop the maintenance that may malfunction, reduce the load current of the primary winding, wear insulating boots, wear insulating gloves, use something with an insulating handle, and use the electrical current transformer at the nearest test terminal. The secondary short-circuit, and deal with the open point. If the secondary wiring terminal screws are loose and cause an open circuit on the secondary side, if the load is reduced and the necessary safety measures are taken, the loose screws can be tightened without power failure. If there is an internal problem, the power should be cut off. If the Electrical Current Transformer is severely damaged, the load should be transported and the power cut should be handled.

(2) Ensure that the secondary side of the Electrical Current Transformer is firmly grounded. In order to avoid the primary and secondary winding insulation breakdown, the primary side high voltage rushes into the secondary side, endangering the safety of equipment and personnel, the secondary side of the Electrical Current Transformer must be securely grounded. However, it should be noted that the secondary circuit of the Electrical Current Transformer only allows one point of grounding, because if there are two grounding points, it will cause shunting, increase measurement errors or affect the correctness of maintenance actions.

(3) Electrical Current Transformer should operate within the scope of the technical parameters of the rules. The load connected to the secondary winding should be within the load limited by the precision level, and the load should generally be maintained at 25% to 100% of the additional secondary load.

(4) The Electrical Current Transformer cannot run beyond the agreed capacity for a long time. Otherwise, not only will the core and the secondary winding overheat, the insulation aging will accelerate, and the damage will be caused because of the full iron core. Try to handle the load when the Current Transformer is overloaded.

(5) The Electrical Current Transformer is connected in series in the loop of the primary equipment, and cannot be detached from operation alone like a voltage transformer. Electrical Current Transformer has an abnormality or failure that needs to exit operation, and the corresponding primary equipment must also exit operation at the same time.