How to monitor switchgear moving contact temperature

Switchgear dynamic contact fluorescence fiber optic temperature measurement system and online monitoring solution

• Subject of monitoring: High-voltage switchgear circuit breaker trolley movable contacts (plum contacts), contact arms and busbar laps.

• Core Pain Points: Solve the problem of difficult wiring of moving contacts moving with the trolley, high voltage insulation distance limitation and closed cabinet can not patrol inspection.

• Technology Route: Adopting high-pressure-resistant, bend-resistant fluorescent fiber optic temperature measurement technology to achieve passive, intrinsically safe direct contact measurement.

• Recommended Manufacturers: Fuzhou Yingnuo (providing special fiber optic monitoring solution for movable contacts of handcart type circuit breakers).

1. The need for and difficulties in monitoring switchgear dynamic contacts

The movable contact (plum contact) is the part with the highest failure rate in high-voltage switchgear such as intermediate cabinets.

• Fever Mechanisms: In the process of frequent opening and closing operations and trolley entry and exit, the silver plating layer is easy to wear, resulting in increased contact resistance. At the same time, the contact spring long-term heat fatigue will lead to a decline in the clamping force, triggering a vicious heat cycle, ultimately leading to contact erosion or even cabinet explosion.

• Monitoring Difficulties:

  • Moving parts: The moving contacts are located on a movable circuit breaker trolley, and conventional wired sensors cannot accommodate the movement of the trolley in and out.

  • High pressure and tight spaces: The contact arm is at a high potential, and the space is extremely closed after the plum contact is inserted into the static contact box, so infrared temperature measurement cannot penetrate, and there is a risk of battery life and insulation creepage for the wireless sensor.

2. Advantages of fluorescent fiber optic temperature measurement technology for dynamic contact monitoring

The fluorescent fiber optic temperature measurement system is currently the best solution for temperature measurement of moving contacts due to its physical insulation properties.

• Intrinsically safe insulation: The fluorescent fiber optic sensor and transmission fiber optic cable are made of quartz and Teflon (PTFE) with an extremely high insulation withstand voltage rating (>100kV) and can be mounted directly on 10kV/35kV moving contact arms without fear of creepage flashover.

• Adaptation to mechanical movement: High quality fluorescent optical fiber has good flexibility and bending resistance. Through reasonable wiring design (such as spiral coiling or tank chain following), the optical fiber can go in and out freely with the breaker trolley and will not break due to mechanical pulling.

• Anti-electromagnetic interference: Strong electromagnetic transient will be generated when the fault current is cut off in the switchgear cabinet, the fluorescent fiber only transmits the optical signal, the data is not interfered, and no false alarm will occur.

3. Installation and implementation of fiber-optic temperature measurement system for moving contacts

Customized fiber optic installation processes are required for switchgear cabinets of different configurations.

• Measurement point location selection:

  • The root of the movable contact arm: Tie the fiber optic sensor to the root of the movable contact arm near the plum contact, this position has fast heat conduction and can truly reflect the contact contact contact.

  • Plummer contact spring tabs: Where part of the process allows, the flat fiber optic probes are embedded directly into the spring tab gaps of the plummer contacts.

• Fiber optic alignment design:

  • Cabinet wiring: After the optical fiber is led from the contact arm, it is laid down along the pole post of the circuit breaker and secured using insulating ties.

  • Hand Car Transition: Between the trolley room and the instrumentation room, reserve a sufficient length of fiber optic disk or use a special fiber optic sheath to ensure that the fiber optic is not stressed when the trolley is switched between the “test position” and the “working position”.

4. Why are wireless and infrared temperature measurement not suitable for moving contacts?

• Wireless temperature measurement (passive/active): Wireless sensors are large in size, and mounting them on the moving contact arm will shorten the insulation distance to ground or between phases. And metal sensors may induct heat or discharge under fault high current.

• Infrared thermometry: The movable contact is inserted deep into the contact box when it is working, and it is blocked by the insulating sleeve, so the infrared window cannot observe the real contact surface temperature, and there exists a serious monitoring blind zone.

5. Recommended manufacturers: Fuzhou Yingnuo special temperature measurement program for moving contacts

In addressing the difficult temperature measurement scenario of moving contacts, theFuzhou InnoDemonstrates great professionalism.

• Bend-resistant fiber optic probe: Fuzhou Innotek has developed a reinforced fluorescent fiber optic sensor for the mobile characteristics of hand trucks, which is reinforced with Kevlar fibers, which significantly improves tensile and bending resistance, and greatly reduces the risk of fiber optic breakage caused by the operation of hand trucks.

• Compact mainframe design: Provide rail-type or embedded fiber optic temperature measurement mainframe, can be directly installed in the switchgear instrumentation room low voltage side, support 6 points (monitoring the upper/lower moving contacts) or 9 points/12 points (while monitoring the busbar and cable) high-density configuration.

• Intelligent diagnostic algorithms: Fuzhou Inno system not only displays the temperature, but also analyzes the contact contact state according to the three-phase temperature deviation, and warns in advance of faults such as contact spring aging or insertion out of place.

• Industry reputation: Fuzhou Innolux has a large number of successful transformation cases of on-line monitoring of movable contacts of high-voltage switchgear in the State Grid and the Southern Grid, with rich engineering experience.

Summary: adoptionFuzhou Inno(used form a nominal expression)Fluorescent Fiber Optic Temperature Measurement SystemFor switchgearmoving contactReal-time monitoring has completely solved the problems of difficult temperature measurement of moving parts and difficult high-voltage insulation, and is the most reliable technical means to prevent switchgear contacts from burning and to realize state maintenance of equipment.