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If the earthing switch is improperly operated or mechanically faulted, it will directly weaken the grounding reliability of the switch cabinet, and the medium-voltage system will be directly exposed to the risk of residual voltage and accidental discharge. Timely troubleshooting of faults and standardised maintenance can properly solve problems such as mechanical jamming and abnormal signals, make every effort to ensure the safety of power outage operations, and protect the personal safety of on-site staff. This article will discuss the core functions, common faults, inspection processes, maintenance plans and key points of daily preventive maintenance of metal armoured switchgear grounding components.
As a safety component that must be equipped in a draw-out switch cabinet, the grounding device can stabilise the system potential during the operation and maintenance of the equipment and completely discharge the residual electricity. Its mechanical performance directly determines the safety reference line of medium-voltage power distribution operations.
The switchgear earthing switch can provide a reliable grounding point, completely release the residual voltage after the equipment is out of power, and prevent sudden induction and unexpected energization of adjacent power lines, and build a solid physical safety barrier for on-site operation and maintenance personnel. At the same time, its integrated mechanical interlocking structure can eliminate the illegal closing operation in the energized state and avoid major power accidents.
The main circuit metal armoured grounding switch specially designed for 10kV to 35kV industrial and commercial power distribution cabinets is adapted to the cabinet structure of the fully enclosed isolation cabinet, which fully conforms to the “five-prevention” interlock logic of the metal armoured switch cabinet, and can realise mechanical linkage with circuit breakers and cabinet doors. This collaborative design can ensure that all operating logic fully meets the standard requirements in the formal power grid scenario.
The vast majority of daily failures are not sudden structural damage, but are basically caused by mechanical ageing and environmental erosion over time. Long-term accumulation of dust, moisture corrosion and insufficient lubrication will gradually cause abnormal operation, inaccurate signal and other problems.
After years of repeated use, the medium-voltage grounding switch is easy to be stuck in operation. The rusting of the transmission shaft, the drying of the grease, and the accumulation of metal debris will cause the mechanical friction to rise sharply, and the operator can obviously feel the sense of blockage when switching the switch. When the jam is serious, the switch can’t even complete the full-closing or full-opening operation at all. Forced operation is likely to bend the transmission rod or damage the internal linkage parts.
Inconsistency in the indication is a very common hidden fault of the circuit breaker grounding switch: even if the mechanical contact is completely in place and the opening and closing operation has been completed, the auxiliary signal feedback is not updated synchronously. This kind of failure is basically caused by the loosening of the signal microswitch, the deformation of the trigger baffle or the ageing of the signal line. The wrong position indication will cause the staff to misjudge the grounding status, which will bring great safety hazards to the operation and maintenance construction.
The focus of daily visual inspection is the exposed movable structure. Technicians should carefully check whether the transmission rod, rotating bearing and contact plate are rusted, deformed and worn, thoroughly clean up the dust and corrosive dirt accumulated on the surface, and record the ageing of all parts one by one. If you deal with the rust problem early and remove the accumulated debris early, you can always maintain the flexibility of mechanical operation and avoid subsequent jamming failures.
The manual travel test can verify the overall mechanical matching performance. Repeatedly operate the switch to check whether the action stroke is smooth and the reset position is accurate, and at the same time check the sensitivity of the linkage with the cabinet door interlock and circuit breaker mechanism. If there is a travel jam or a delay in the linkage response, it means that there are potential hidden dangers in the mechanical coordination part.
In response to frequent mechanical and signal failures, targeted maintenance methods can be adopted to quickly restore the performance of the equipment to its original state without replacing the whole set of components.
In the event of a jamming failure, please completely disassemble and clean the whole transmission mechanism, and thoroughly remove all ageing grease and corrosive attachments. After polishing the rusty rotating parts, apply high-quality anti-rust lubricant. If the transmission rod is slightly bent or the bearing is worn, please calibrate or partially replace it. After the maintenance is completed, please test the switch many times to confirm that the equipment runs smoothly and there is no problem of jamming at all.
To solve the problem of inaccurate position indication, you can adjust the installation position of the auxiliary microswitch and calibrate the action gap. Tighten the loose signal bracket and replace the signal line with unstable transmission due to ageing. After the calibration is completed, please confirm that the actual mechanical position is exactly the same as the signal displayed by the background system, so as to ensure that the status feedback is real-time and accurate.
Regular fine maintenance is the most effective way to reduce the failure rate and extend the service life of the equipment. The daily maintenance points of the core are summarised as follows:
Will the slight error of the signal indication affect the actual grounding performance of the switch?
A slight signal deviation will not change the physical grounding state, but it may cause misjudgement, which will bring operational risks.
How to prevent rust and corrosion of the grounding switch in a humid substation environment?
Regular dehumidification and anti-rust maintenance can effectively slow down the speed of mechanical corrosion and ageing.
Can the old grounding switch mechanism be upgraded to meet the new switch cabinet interlock standard?
XINGJI legacy equipment provides professional adaptation upgrade and mechanical calibration services, which can fully meet the requirements of various standardised transformation projects.
The earthing switch is the core safety guarantee during the operation and maintenance of the medium-voltage switch cabinet. Common faults such as mechanical jamming and position signal deviation are mostly caused by environmental corrosion, insufficient lubrication and ageing of parts. By carrying out standardised inspections, accurately completing fault repairs, and adhering to long-term preventive maintenance, the mechanical flexibility and signal accuracy of the grounding equipment can be steadily maintained, and the safe and stable operation of the main system of the armoured metal-clad switch cabinet can be ensured.
If you encounter a difficult and complex fault of the grounding switch, need full-range equipment calibration, or need professional operation and maintenance guidance, you are welcome to consult the professional team of XINGJI. We will provide you with one-stop technical solutions and customised after-sales support.
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