1. Allowable operation mode of current transformer
(1) Allowable operating capacity. The current transformer should operate within the rated capacity specified on the nameplate. If the operation exceeds the rated capacity of the nameplate, the accuracy will be reduced, the measurement error will increase, and the meter reading will be inaccurate. This is the same as the voltage transformer.
(2) Allowable current on the primary side. The primary side current of the current transformer allows long-term operation under 1.1 times the rated current. Long-term overload operation will increase the measurement error and cause the winding to overheat or damage. The secondary side current of the current transformer is generally 5A or 1A, and the commonly used is 5A. When the current transformer is in normal operation, its secondary side loop is close to a short-circuit state.
(3) The secondary side of the current transformer cannot be opened during operation. If the secondary side of the current transformer in operation is open, high voltage will appear on the secondary side, which will endanger the secondary equipment and personal safety. If the work needs to disconnect the secondary circuit (such as removing the instrument), before disconnecting, the secondary side terminal should be reliably shorted with a connecting piece.
(4) Both the secondary side of the current transformer and the iron core should be reliably grounded. (Prevent primary and secondary insulation breakdown, the primary high-voltage from entering the secondary side)
(5) The load impedance of the secondary side shall not be greater than the rated load impedance (to ensure the accuracy of the measurement)
(6) When wiring the current transformer, pay attention to the polarity of its terminals
(7) TA must not be connected to the secondary side of the TV (so as to avoid the risk of high voltage due to the approximate open circuit of TA)
(8) When working, a person must be supervised, use insulating tools, and stand on the insulating mat.
2. Patrol inspection of current transformer operation
(1) Check that the porcelain part should be clean, free from damage, cracks, and discharge traces.
(2) Check that the oil level should be normal, the oil color should be transparent and not blackened, and there should be no leakage or oil leakage.
(3) Check that the current transformer should have no abnormal sound and burnt smell.
(4) Check that the lead connector on the primary side should be firm, and the crimping screw should not be loose or overheated.
(5) Check that the grounding wire of the secondary winding should be in good condition, and the grounding should be firm, without looseness or breakage.
(6) Check that the terminal box should be clean, free from moisture, and the secondary terminals are in good contact, and there is no open circuit, discharge or ignition.