Why is it strictly forbidden to install a dissolver in the secondary side circuit of the current tra

When the current transformer is in working condition, it is relative to a step-up transformer. If a fuse is installed on the secondary side of the current transformer, when the fuse is fused, the secondary side is equivalent to an open circuit, which will generate high voltage and endanger the safety of work and inspection personnel.

Because the secondary side circuit of the current transformer cannot be opened!

in a live current transformer.

When working on the secondary circuit, these safety measures should be taken: (1) It is strictly forbidden to open the secondary side of the current transformer.

2) The secondary winding of the short-circuit current transformer must use a short-circuit piece or a short line, and it is strictly forbidden to use wire winding. (3) In the current transformer with short-circuit terminals.

Any work carried out between the guide and the line should have strict safety measures, and fill in the "secondary work safety measures ticket".

If necessary, apply for the suspension of the relevant protection device, air light, safety automatic device or automatic monitoring system. (4) During work, it is strictly forbidden to disconnect the permanent grounding point of the circuit. (5) When working, there must be a special person to supervise, use insulating tools, and stand on the insulating mat.

Short circuit is not allowed on the secondary side of the accompaniment voltage transformer in the operation ruler line, and () is not allowed on the secondary side of the current transformer.

a.Open. b.Short circuit.

c.Shorted. d.Concatenation.

Correct Answer: Ji Chao Gao A

Answer]: If there is a short circuit on the secondary side of the voltage transformer, it will be caused by the line voltage unchanged due to the primary voltage.

The first and secondary currents increase sharply, causing the windings to heat up and even burn out the insulation, resulting in the high-voltage series of the primary side of the low-voltage circuit on the secondary side, endangering the safety of personnel and equipment.

When the current transformer is in normal operation, the primary side is connected to the measured circuit in series, and the impedance in the current of the measuring instrument connected to the secondary side is very small, which is equivalent to short-circuit operation, the secondary current is very large, and most of the primary current is used to offset the secondary current, so the excitation current is very small. If the secondary side is open, because its primary current does not change, the secondary current is zero, and all the primary currents of Sengao are excitation currents, resulting in serious saturation of the iron core, causing a great increase in iron consumption and overheating of the iron core; At the same time, the high overvoltage induced in the secondary winding endangers the personal safety of equipment and operators.

This is because, because the internal impedance of the voltage transformer is very small, if the secondary circuit is short-circuited, a large current will occurIt will damage the secondary equipment and even endanger personal safety.

2. The secondary side of the current transformer is absolutely not allowed to open the circuit.

Once the secondary side of the current transformer is opened, the current on the primary side will become magnetizing current, which will cause the core to be oversaturated and magnetized, and the heating will be serious and even the coil will be burned. Moreover, when the current transformer is working normally, the secondary side is approximately short circuit.

If it is suddenly opened, the excitation electromotive force suddenly changes from a very small value to a very large value, and the magnetic flux in the core presents a seriously saturated flat-top wave, so the secondary side winding will induce a very high voltage, which can reach thousands of volts, which will endanger the safety of the staff and the insulation performance of the instrument.

Cause of short circuit. 1. The component is damaged.

Short circuits are often caused by damage to insulation or careless wiring. For example, equipment defects caused by aging equipment insulation materials and poor design, manufacturing, installation, and maintenance develop into short circuits [2].

2. Influence of meteorological conditions.

For example, the scintillation discharge caused by lightning strikes, the overhead line due to wind damage, the overhead line backup leakage and the wire icing caused the collapse of the power pole.

3. Man-made destruction.

For example, the staff pulled the switch with load, did not rule out the grounding wire closing and power supply when overhauling the line or equipment, the misoperation of the operation personnel, and the stealing of the wire and the carbon fiber bullet used in the Kosovo war and the Iraq war in the United States.

4. Other reasons for late rental.

Trenching damages cables, birds and beasts kite jumps on current-carrying bare conductors, etc.

The voltage transformer is actually a small transformer, which is short-circuited on the secondary side, which is equivalent to the secondary short-circuit of the "transformer", the voltage transformer is designed according to the rated current, and it can't stand such a large short-circuit current, which will burn the voltage transformer and cause an accident.

And the secondary output voltage of the voltage transformer will be reduced, the voltmeter indication is "zero", the secondary system can not operate safely, and the equipment with low voltage protection may also malfunction, affecting the normal power supply.

After a short circuit occurs, stop the operation of the voltage transformer as soon as possible after judging the accurate fault nature, and immediately notify the secondary system personnel for timely treatment. Although this will affect the secondary relay protection and power metering, it will not cause power outages for users and will not affect the power supply of the system.

When the voltage transformer is running, it is almost a secondary open circuit or close to an open circuit state.