Isolating switch is a high-voltage switchgear with a wide range of applications in power systems. Since the outdoor isolating switch is completely exposed to the atmosphere to work, its operating conditions are relatively harsh,
Prone to mechanical or electrical failures. In particular, the contact part of the contact finger is susceptible to rain, dust and harmful gases, resulting in poor contact and heat generation. The spring that provides the pressure of the contact finger will cause heat to occur.
Heat and annealing reduce the pressure, which further causes the contact fingers to heat up and form a vicious circle, which eventually burns out the contact fingers and causes accidents. During maintenance, only attention is paid to replacing the springs that are obviously failed and broken, and the
The spring with reduced force cannot be judged and replaced, so in the re-operation, the current distribution of each contact finger will be different due to different pressures. The greater the difference, the more uneven the current distribution. After long-term operation, the current distribution will be more uneven.
Poor contact and overheating. The heating of the contact fingers will be a vicious circle, and the bad contact of one contact finger will spread the whole contact bad contact. At the same time, the contact finger pressure of many isolation switches can be adjusted.
When the adjustment pressure is not enough or the adjustment pressure of each contact finger is different, the above phenomenon will also occur. At present, the criterion for most maintenance personnel to judge whether the conductive part is in good or bad contact is to measure its loop resistance.
Considering that the loop resistance is within the qualified range, the overhaul of the conductive part can be successfully completed. In fact, it is not the case. The loop resistance value given in the product manual is the value of the entire conductive loop, which includes the connection
The body resistance and contact resistance of wire terminals, conductive tubes, and finger contacts have a large range and a large margin, which cannot directly reflect the change of contact resistance, but can only explain the conductive loop path.
The test shows that the circuit resistance values of two pairs of contact fingers and four pairs of contact fingers are all within the qualified range. Similarly, the contact finger pressure is large and the resistance value of the small circuit is basically unchanged. In various maintenance guides
There are provisions for measuring the contact pressure of the contact finger in the regulations (regulations) and standards. The recommended measuring tool is a spring scale. In actual work, the pressure of the contact finger should be measured at a high altitude.
Convenient, inaccurate and insecure, the contact finger pressure of some structural isolation switches cannot be measured with a spring balance at all (such as a scissors type). Therefore, the requirement to measure the contact pressure of the contact finger is just a piece of paper. needle
Regarding the current maintenance status of the power generation and power supply system, our company has developed an intelligent tester for measuring the pressure of the contact finger of the high-voltage isolating switch. It only needs the sensor of the test clamp to simulate the contact in each
When you open the contact position of the contact finger, the contact pressure of the contact finger at that time can be displayed and memorized. It effectively solves a big problem of measuring the pressure of the contact finger. The instrument can also be used to contact the disconnect switch manufacturer
Refers to the test of pressure; changing the shape of the pressure sensor can also measure the contact finger pressure of the circuit breaker.
