1、 Measurement of resistance of wire connector
Because the cross section of the wire connector is larger than that of the wire, the contact is good under normal conditions, and the resistance of the connector should be smaller than that of the same length of wire. If the resistance of the connector increases, its value is greater than that of the equal length wire, which indicates that the electrical contact of the connector has deteriorated. If the resistance ratio of the connector to the wire of the same length is greater than 2, the connector is unqualified and should be replaced immediately. According to the regulations, copper wire connectors shall be inspected at least once every five years; aluminum wire and steel core aluminum wire connectors shall be inspected at least once every two years. There are two methods to measure the resistance of connectors.
1. Live measurement of connector resistance: it is carried out with a special inspection rod. The line measured by this method must be horizontally arranged. If it is triangular arrangement, only the connector on the following one or two phases of conductor can be measured.
2. Power failure measurement: when the line power failure, with the battery or substation DC power supply DC current to measure. The principle of measurement is the same as that of live measurement. Generally, the conductor is not dropped down during power failure measurement. Only under special circumstances, such as measuring the connector on the conductor across the valley, the conductor is dropped down on the ground for measurement.
2、 Infrared temperature measurement of wire connector
1. The application scope of infrared temperature measurement of wire connector is the connector of running wire, such as wire connecting pipe, drainage clamp, tension clamp, etc. because of the manufacturing or installation process, these components may have defects, as well as the increase of mechanical tension, long-term vibration, metal fatigue, over-voltage, corrosion of acid, alkali and salt dust, the contact resistance of the internal contact surface of the connector will increase, and then increase With the increase of temperature, when the temperature exceeds 700C, the metal oxidation will intensify, which will eventually lead to the failure of connecting components. Infrared temperature measurement is an important supervision method to prevent connector failure.
2. Infrared temperature measuring instrument is a kind of uncooled infrared thermal TV, which uses pyroelectric tube as detector and chopper modulation mode.
3、 Detection cycle of infrared temperature measurement for wire connector
1. Generally, important tie lines, important loads and heavy load lines should be arranged once a year.
2. The newly-built, reconstructed or overhauled electrical equipment shall be subject to infrared detection once a month after being loaded.
3. For abnormal wire connectors found during inspection, infrared detection at peak load should be arranged at any time, or random sampling test can be arranged in combination with operation mode change and load change.