Intelligent isolation switch contact clamping force tester

1.Overview

Isolation switch is the most widely used high-voltage switchgear in the power system. Due to the fact that outdoor isolation switches are the most direct and severe electrical equipment exposed to the atmosphere and affected by environmental and climatic conditions, their operating conditions are relatively harsh and they are prone to mechanical or electrical failures. Especially the contact part of the touch finger is easily invaded by rainwater, dust, and harmful gases, resulting in poor contact and heating. The spring that provides pressure to the touch finger will anneal due to heating, causing the pressure to decrease. This further leads to a vicious cycle of heat generation and ultimately burns out the touch finger, causing accidents. During maintenance, attention is often only paid to replacing springs that have obvious failures or fractures, and it is impossible to judge and replace those springs with reduced pressure. As a result, during further operation, the distribution of current in each contact finger will vary due to different pressures, and the greater the difference, the more uneven the current distribution. After long-term operation, poor contact may occur and overheating may occur. The heating of the touch finger can lead to a vicious cycle, where poor contact between one touch finger can spread throughout the entire contact. At the same time, there are many isolation switches with adjustable finger pressure. If the pressure adjustment during maintenance is insufficient or there are differences in the adjustment pressure of each finger, the above phenomenon will also occur.

At present, the majority of maintenance personnel judge the contact quality of conductive parts by measuring their circuit resistance. If the circuit resistance is within the qualified range, the maintenance work of conductive parts can be successfully completed. In fact, the circuit resistance value given in the product manual is the value of the entire conductive circuit, including the body resistance and contact resistance of the wiring terminals, conductive tubes, contact fingers, etc. It has a large range and margin, and cannot directly reflect changes in contact resistance. It can only indicate the conductive circuit path. The experiment shows that the circuit resistance values of two pairs of contact fingers and four pairs of contact fingers are within the qualified range. Similarly, there was no significant change in the resistance value of the small circuit due to high finger pressure.

In various maintenance procedures and standards, there are provisions for measuring the contact pressure of the touch finger. The recommended measuring tool is a spring scale. In practical work, measuring the contact pressure of the touch finger needs to be done at high altitude. Using a spring scale to measure pressure is not only inconvenient, inaccurate, but also unsafe. For some structures of isolation switches, the contact pressure of the touch finger cannot be measured by a spring scale at all (such as scissor type). So, the requirement to measure finger contact pressure is just a piece of paper.

In response to the current maintenance status of the power supply system, our company has independently developed an intelligent touch finger pressure detector for measuring the contact finger pressure of isolation switches. It only needs to open the sensor of the analog contact at each pair of touch finger contact positions (such as the transfer type) or clamp the analog static contact with the moving contact knife (such as the scissor type), which can display the contact pressure of the touch finger at this time and remember it. Effectively solved a major problem in measuring finger pressure.

This instrument can also be used for the inspection of contact finger pressure in isolation switch manufacturers. Changing the shape of the pressure sensor can also measure the finger pressure of the circuit breaker.

This manual is only applicable to clamp type<scissor type>isolation switches

2.Main technical parameters

Power supply voltage: AC 220 V

Power dissipation power: ≤ 20 W

Measurement range: ≤ 2000 N

Measurement error: ≤ 1%

Measuring diameter (static contact): 40mm

50mm, 60mm (customizable)

Built in power supply working time: ≥ 6 hours

Sensor signal line length: 10 meters