The open circuit on the secondary side of the current transformer is a danger you wouldn't even thin

In electrical work, current transformers play a crucial role, but there is an iron rule that must be remembered - their secondary side must not be open circuited! This is not just a casual statement

1. Once violated, the consequences are unimaginable, with equipment damage and personal safety accidents likely to follow one after another.Dangerous voltage strikes, endangering life safety

When the current transformer is working normally, the secondary circuit is almost in a short-circuit state, and the output voltage is very low. But if the secondary side opens up, it immediately becomes a "boost demon". At this point, the large current on the primary side becomes the excitation current, and the magnetic flux in the iron core increases rapidly like riding a rocket, quickly reaching a severe saturation state. According to the law of electromagnetic induction, the secondary winding will induce extremely high peak wave voltage, several thousand volts or even tens of thousands of volts. Such high voltage can easily break through the insulation of the secondary circuit. If the operator accidentally touches it, it is a fatal risk of electric shock, and

The instruments and relay protection equipment connected to the car will also suffer, being burned beyond recognition.

2. The iron core overheated and went crazy, causing the transformer to be destroyed in an instant

During normal operation, the magnetic flux generated by the primary side current is similar in magnitude and opposite in direction to the magnetic flux generated by the secondary side current. When they cancel each other out, the total magnetic flux in the iron core is very small and the losses are also minimal. But when the secondary side opens, the secondary current disappears, and the cancellation effect is also lost. The strong magnetic field generated by the primary side current causes the iron core to enter a deep magnetic saturation state. This is a big deal. The iron core loss (iron loss) has increased dramatically, and the iron core is heating up like a furnace, which will soon damage the winding

The insulation was burned out, and ultimately the transformer was completely scrapped.

3. Safe use, these regulations cannot be forgotten

To ensure safety, there are strict regulations that must be followed when using and maintaining current transformers. Never install fuses or any switchable devices in the secondary circuit. If it is necessary to disassemble secondary side instruments such as ammeters and relays during operation, the secondary side surge protector must be reliably short circuited with wires or dedicated short-circuit plates before operation. In addition, one end of the secondary winding of the current transformer must be reliably grounded to prevent the high voltage on the primary side from being affected

Insulation damage entering the secondary low-voltage circuit provides an additional layer of safety protection.

The key safety points for short-circuit operation on the secondary side of the current transformer are fully mastered. This is a critical safety operation in electrical work and must be strictly followed in sequence.

1. Preparation before operation should be sufficient

Special short circuits or short-circuit plates must be used, with a sufficiently large cross-sectional area to stably withstand possible currents. Do not use ordinary fuses or

Thin wires, otherwise if they melt and cause an open circuit, it will be a big problem. Operators also need to take protective measures, wear insulated gloves, stand on insulation pads, and use gloves to isolate themselves

The tool of the edge handle tightly protects oneself.

2. Do not be careless when performing short-circuit operations. The core principle is to short-circuit first and then disconnect the wire. Before dismantling the instrument or relay, it is necessary to use a short circuit at the wiring terminal to reliably connect the two terminals of the secondary winding. And the terminal screws need to be tightened. If there is poor contact, it is like connecting a large resistor in series, which can still cause high voltage.

3. After operation, confirm that the operation cannot be reduced, or connect the backup short circuit first before switching.

After completing the short circuit, use tools to disassemble the instrument or relay. At this point, the secondary current will form a circuit through a short path and will not open. Remember,

It is prohibited to disconnect the secondary side of the current transformer directly for instrument calibration after opening the circuit. If verification is required, a dedicated current transformer must be used to open a one path switch

4. When restoring the circuit, caution should be taken to reset the reading to zero, as it may also burn out the secondary winding due to high current heating.

After completing the work, first connect the instrument or relay back to the terminal, confirm that the connection is correct, and then remove the short circuit to restore the normal operation of the current transformer

Make it. If the instrument fails to disconnect the short circuit after normal operation, the secondary side of the current transformer will remain short circuited. Although it will not generate high voltage, it will cause the ammeter to malfunction

Open circuit is strictly prohibited on the secondary side of current transformers, and the core is to prevent high voltage, ensure safety, and protect equipment. If the high current on the primary side is cancelled out by the circuit, the secondary side will feel

The deadly high voltage may not only burn out the transformer, but also seriously threaten personal safety, and cause a series of problems such as overheating of the iron core, failure of measuring and protective devices, etc