Does the primary side of the voltage transformer need to be grounded? Why?

If the primary winding of the voltage transformer adopts star wiring, the neutral point of the primary winding can be grounded, and the phase voltage and line voltage can be measured on the secondary side when grounded, and the outgoing line voltage can only be measured when it is not grounded. The secondary voltage transformer is not allowed to be short-circuited, and the fuse needs to be connected; The secondary of the current transformer is not allowed to open the circuit, and it is not allowed to connect the fuse; There is a mistake in what is said above.

The primary side is connected to the phase line, how can it be grounded, the ground is short-circuited!

The secondary side, which is the side that is connected to the meter, must be grounded, and no open circuit or fuse is allowed.

For a symmetrical three-phase system, the line voltage is equal to 3 times the root number of the phase voltage, and in the case of a preliminary measurement, either the phase voltage or the line voltage can be measured.

For three-phase monitoring or where accurate measurements are required:

1. If you only measure the line voltage, you can use the method of two voltage transformers V-type connection and three voltmeters to measure the three-phase voltage.

Now some measurement devices with vector arithmetic functions, such as the DT digital transmitter developed by Hunan Yinhe Electric, each transmitter has two measurement channels, and the transformer VV connection method cooperates, and a digital transmitter can measure the three-phase voltage.

2. If it is necessary to measure the phase voltage and line voltage, the three-phase phase voltage should be measured by the Y-type connection method of three transformers, and after the three-phase phase voltage is measured, the three-phase line voltage can be accurately calculated by vector operation. Conversely, the outgoing voltage cannot be measured and the phase voltage cannot be reversed.

1. There should be a grounding point on the secondary side of the voltage transformer, which is mainly for safety considerations. When the insulation between the windings of the primary and secondary side is broken down by the high voltage, the high voltage on the primary side will be channeled to the secondary side, and the grounding of the secondary side can ensure the safety of personnel and equipment. In addition, by grounding, it is possible to supply a phase voltage to the insulation monitoring device.

2. There should be a little grounding on the secondary side of the current transformer. Since the primary side of the high-voltage current transformer is high-voltage, when the high-voltage breakdown occurs between the first and second coils due to insulation damage, it will cause the high-voltage to flow into the low-voltage. If the secondary coil is grounded, the high voltage will be introduced into the ground, so that the secondary coil maintains the ground potential, thus ensuring the safety of personnel and equipment.

Extended information: secondary grounding of transformer: refers to the grounding of the S2 terminal of the current transformer, or the grounding of the N terminal of the voltage transformer.

As long as the single point is grounded, because the transformer is isolated between the second and the first, before grounding, the secondary winding has no potential relationship with the earth, after grounding, the transformer will not form a loop with the ground, and the current will not flow to the ground during normal operation.

When the insulation between the primary winding and the secondary winding is damaged, the primary high voltage is connected to the secondary circuit, and the primary high voltage has a fixed potential relationship with the earth, and the current will flow to the earth, and the secondary voltage of the transformer will be clamped to the ground voltage to ensure the safety of the secondary instrument and personal safety.

In a normal situation, the external shell of the current transformer metal should be grounded to ensure safety. Fully grounded to prevent the enclosure from being electrified and avoiding the risk of electric shock. However, whether it is necessary to re-infiltrate the specific area depends on the actual situation, such as the use of the equipment, the environment, the installation location and other factors in the ridge.

When installing an electric inductor, you should carefully read the relevant installation instructions and safety regulations to ensure that the ground connection is carried out correctly.

The <>-friendly transformer is a kind of power permeability measurement and protection equipment, which can convert the current of high voltage into the current of low voltage for easy measurement and protection. When using a current lead old ridge transformer, it is usually necessary to ground it to ensure safety and reliability. Grounding can effectively prevent the housing and internal components of the current transformer from being electrified, thus avoiding electric shock and other safety accidents.

In addition, grounding can also improve the immunity of the current transformer and reduce the influence of external electromagnetic interference on the measurement results. Therefore, it is recommended that every current transformer be grounded.

In order to ensure safety, one is equipment safety, and the other is personal safety. Because there is a distributed capacitance between the primary winding and the secondary winding and between the secondary winding and the ground of the current transformer. Then the voltage division of this distributed capacitor causes the secondary winding to produce a higher voltage to the ground. Still.

If the insulation between the primary winding and the secondary winding is damaged due to some reasons, the high voltage of the primary circuit will be directly added to the secondary circuit, which is very harmful to the secondary equipment and personal safety. Therefore, the secondary side of the current transformer must be grounded, and the secondary circuit has one and only one grounding point, and multiple grounding points are not allowed.

The secondary circuit of the current transformer with several groups of current transformer windings combined and directly connected with the circuit should be grounded at the first level and the current (main control room), and the access point selected by the grounding wire should be reasonable, and when any group of current circuits is disconnected, the current circuit in operation cannot lose the grounding point.