【Daily Topic】【Electrical Edition 20160706】

The secondary winding of the voltage transformer must not be short-circuited. Since the normal load of a voltage transformer are instruments with high impedance, when the voltage coil of a relay or that of an automatic device shorts out, the impedance of the secondary circuit becomes merely that of the transformer’s secondary winding. As a result, a large short-circuit current is generated in the secondary circuit, which affects the readings of the measuring instruments, can cause the relay protection systems to malfunction, and may even destroy the transformer.

The primary side is connected to high voltage, while the secondary side has low voltage; it is also equipped with protection devices and meters. Workers often come into contact with these protection devices and meters. If the insulation fails and high voltage gets into the low-voltage circuit, it could pose a threat to the personnel responsible for operating the relay protection systems and the maintenance staff. Additionally, since the insulation level in the secondary circuit is low, it may be damaged if there is no ground connection, leading to damage to the meters and relays. To ensure the safety of people and equipment, the secondary side of voltage transformers must be grounded

Grounding the secondary side of the transformer is done for the safety of personnel and equipment

The grounding of the secondary side of a voltage transformer is a type of protective grounding; its purpose is to prevent breakdown of the primary insulation, which could allow high voltage to penetrate into the low-voltage side and pose a risk to human safety and equipment. The primary winding of the voltage transformer is connected to the high-voltage system. If the insulation between the primary and secondary sides of a voltage transformer in operation is damaged and broken down, high voltage will penetrate into the secondary circuit, which not only damages the secondary equipment but also poses a serious threat to the safety of electrical workers. Therefore, one point on the secondary side of the voltage transformer must be grounded.

The secondary grounding of voltage transformers is a type of protective grounding, intended to safeguard the safety of people and equipment. This is because, during operation, the primary side of a voltage transformer is under high voltage, while the secondary side has a fixed low voltage (for example, if the voltage at the primary coil of a voltage transformer is 10,000 V, then the fixed voltage on the secondary side is 100 V; thus, the secondary voltage is only 1/100 of the primary voltage). If the insulation between the primary and secondary sides of a voltage transformer is broken down, the high voltage on the primary side will be applied directly to the secondary coil. The insulation level of the instruments and relay protection devices connected to the secondary coil is quite low, and they are often in contact with people; as a result, not only are the secondary devices damaged, but it also poses a direct threat to the safety of the workers. Therefore, to ensure the safety of personnel and equipment, it is required that in addition to grounding the enclosure of the voltage transformer, one point of the secondary coil must also be reliably grounded

Because if the insulation between the primary and secondary sides is damaged, the high voltage from the primary side can leak to the secondary side, posing a threat to the safety of people and equipment; therefore, the secondary side must be grounded.

The primary side of a voltage transformer is connected to high voltage, while the secondary side has low voltage and is connected to protection devices and meters. Workers often come into contact with these protection devices and meters; if the insulation fails and high voltage gets into the low-voltage circuit, it could pose a threat to the personnel responsible for operating the relay protection systems and the maintenance staff. Additionally, since the insulation level in the secondary circuit is low, it may be damaged if there is no ground connection, resulting in damage to the meters and relays. To ensure the safety of people and equipment, the secondary side of a voltage transformer must be grounded.

This post was last edited by hesonchang214 on 2016-7-7 at 22:43. The primary side of a voltage transformer is connected to high voltage, while the secondary side has low voltage and is connected to protection devices and meters. Workers often come into contact with these protection devices and meters; if the insulation fails and high voltage gets into the low-voltage circuit, it could pose a threat to the personnel responsible for operating the relay protection systems and the maintenance staff. Additionally, since the insulation level in the secondary circuit is low, it may be damaged if there is no ground connection, leading to damage to the meters and relays. To ensure the safety of people and equipment, the secondary side of a voltage transformer must be grounded.

The secondary side of the voltage transformer must have a grounding point, primarily for safety reasons. When the insulation between the primary and secondary windings is broken down by high voltage, the high voltage from the primary side can leak to the secondary side. The grounding of the secondary side ensures the safety of personnel and equipment. Additionally, by grounding, phase voltage can be provided to the insulation monitoring device.

The grounding of the secondary sides of voltage transformers and current transformers is considered protective grounding. Because if the insulation between the primary and secondary sides is damaged, the high voltage from the primary side can leak to the secondary side, posing a threat to the safety of people and equipment; therefore, the secondary side must be grounded.