Online monitoring method of multipoint earthing of clamping piece of transformer

Abstract

The invention provides an online monitoring method of multipoint earthing of a clamping piece of a transformer, which is characterized by series-connecting a device in an earthing net wire of the clamping piece. The device comprises a current transformer, an ammeter, an adjustable resistor and a full metal jacket. The ammeter is series-connected on the secondary side of the current transformer. The ammeter range has double-layer scales. The adjustable resistor is series-connected on the primary side of the ammeter. The current transformer, the ammeter and the adjustable resistor are all installed in the full metal jacket, and a window for observing the current is only reserved. A housing of the device is singly earthed. The indicated number of the ammeter is observed, and if the earthing current flowing through the clamping piece of the transformer exceeds 100mA, the adjustable resistor is adjusted to enable the current to reach the value displayed when the transformer runs normally. The invention can timely and accurately monitor the state of the clamping piece of the transformer in real time and simultaneously adjust the current-limiting resistance according to the earthing current after the clamping piece is earthed in multipoint so as to control the current flowing through the clamping piece to achieve the aim of protecting the transformer.

Description

technical field [0001] The invention relates to a method for on-line monitoring when a clamp of a large-scale power transformer iron core is grounded at multiple points. Background technique [0002] In the power system, the main transformer is the most important equipment in the substation (station), and it is also the equipment that is easy to cause accidents. Once the main transformer fails, the substation (station) will be forced to shut down, which will directly affect the safe and reliable operation of the power system and cause great economic losses. Among the many types of transformer faults, the multi-point grounding of the iron core clamps is a common fault. Therefore, it is very important to accurately diagnose the multi-point grounding faults of the main transformer iron core clamps and eliminate them in the bud. [0003] The clamps of the main transformer core include: the upper and lower iron yokes for fixing the iron core, the core bolts, the upper and lower ...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: 1), the multi-point grounding fault of the clamp can be generated at any time, once it occurs, it cannot be found in time

2) Sometimes the multi-point grounding point of the clamp is instantaneous (within a period of time) or intermittent. When the grounding occurs, no monitoring is carried out, and the grounding point disappears during detection

3) When using a card meter to measure the grounding current of the clamp, it belongs to live work. The staff must hold a live work certificate and apply for a work ticket for live work. The working procedures are relatively complicated.

4) When measuring the ground current with a card meter, the measured data is inaccurate due to the magnetic flux leakage around the running transformer

5) After finding that the clamps are grounded at multiple points, it needs to be dealt with by a power outage hanging cover, which generally takes 7 working days

It is not conducive to safe and reliable power supply, reduces economic benefits, and at the same time takes labor and time

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