The research focuses on the development of the signal detection interface device for SF6 density relays. The following technical indicators need to be achieved for the development requirements: the interface device can match multiple signal ports of the tested equipment, making it suitable for several commonly used SF6 density relays; the interface device matches different node modes for different models of SF6 density relays, achieving fast and accurate results; it allows the SF6 density relay to be placed upright during verification; the cable part uses high-purity copper, multi-strand flexible cable, high-density shielding wrapping, and strong anti-interference properties; the device is resistant to high temperature, plugging and pulling, has the good load-bearing capacity, corrosion resistance, does not rust, has strong insulation and high flame retardancy.
The SF6 density relay signal detection interface device is a highly efficient improvement on the current clip detection method used in SF6 density relay verification work.
Different from the traditional method of using multiple clips for clamping, the detection interface device does not require the use of multiple clips. Instead, the interface is designed as an upright fixed tool that can be compatible with multiple equipment signal ports. The device is designed through in-depth research on the interface design, SF6 density relay fixing bracket, and material selection process, making it more rapid, safe, and reliable.
1. Development of the interface device
The interface device is mainly composed of three parts. The front end is a preset joint, the middle part is the main joint, and the rear end is a locking screw. The front end of the preset joint has a density relay port with multiple contact points; the effective connection between the preset joint and the main joint is achieved through the contact points; the main joint is a portable handle-type rod bracket, with an interface for connecting testing instruments below the bracket; the locking screw at the rear end is divided into three sections, two shorter locking screws and a longer centre locking screw in the middle. The assembly process is very simple, mainly involving the closure and connection of the three parts. The preset joint and the main joint are connected, and the locking screw is tightened. Then, the contact points of the preset joint are arranged in advance, and the resulting configuration is named as one specification.
The interface device needs to match multiple signal ports of the tested equipment, making it suitable for several commonly used SF6 density relays. In the actual testing process, there are different node modes, including single alarm, single interlock, double alarm, and double interlock. The interface device needs to accurately match different node modes for different models of SF6 density relays, and the connection with the signal port of the SF6 density relay needs to be compatible, safe and reliable. The material of the interface device needs to have good insulation, durability, and should not loosen or damage easily.
Usage instructions: connect the preset joint and the main joint, and tighten the locking screw. Arrange the contact points of the preset joint in advance, and name the resulting configuration as one specification.
2. Development of the SF6 density relay fixing bracket
Develop an insulating bracket that can fix the tested equipment. The bracket can connect the measuring port and the signal port at the same time. Various types of transition threaded joints are provided at the connection between the bracket and the measuring port to match different types of SF6 density relays. The bracket needs to be solid, reliable, able to bear weight, and have stable support and good insulation.
3. Material selection and production technology
The signal conversion part uses aviation plug sockets, and the surface needs to be flat and beautiful. The metal part is made of solid copper needle gold-plated material, which is plug-resistant and anti-oxidation; the insulating part is made of high-quality PPS material, which is resistant to high temperature and has high insulation and flame retardancy; 316 stainless steel screws, anti-corrosion, no rust. The wire core and the internal metal gasket are connected by soldering, which has high reliability. The cable part is made of high-purity red copper, multi-strand copper wire flexible cable, high-density shielding wrapping, and strong anti-interference. Black plastic sheath, resistant to cold, oil, acid and alkali, and bending.