1. Details of electricity test methods
It is not necessary to contact the live conductor directly for testing the electroscope. Generally, the clear luminous voltage of the electroscope is not more than 25% of the rated voltage. Therefore, as long as the intact electroscope is close to the electrified body, it will emit light; to check the electricity with the insulating rod, it is necessary to prevent the conductor from being hooked or against. The structure of outdoor equipment is high, so it is difficult to test the electricity with insulated pull rod, and only judge whether the equipment is electrified according to no spark and discharge sound. During the day, the sparks can't be seen clearly, mainly by listening and playing the electric sound. The background noise of the substation is very large, and the thought is a little less concentrated, so it is easy to make a wrong judgment. Therefore, the operation method is very important. During the power test, if the insulation rod is hooked or against the conductor, there will be no spark or discharge sound even if there is electricity. Because there is no discharge gap in the actual connection, the correct way is to keep the insulated pull rod and the conductor in virtual connection or rub back and forth on the conductor surface. If the electrical equipment is electrified, sparks and discharge sound will be generated through the discharge gap.
2. Safety requirements for power test in progress
For high-voltage power test, the operator must wear insulating gloves; during power test, the qualified, valid and voltage level of the system must be used. In particular, it is forbidden to mix with the electroscope that does not meet the system voltage level. Because, in the low-voltage distribution system, the use of electroscope with high voltage level may not be able to detect the power supply; on the contrary, the safety of the operator can not be guaranteed; in rainy days, the use of ordinary electroscope or insulated pull rod is prohibited, so as to avoid personal accidents caused by moisture flashover or surface discharge; first, the inspection of electrical appliances on the equipment with power supply shall be confirmed to be good; in two cases of power-off equipment Side and parts requiring short-circuit grounding shall be tested by phase.
It is the key to distinguish voltage correctly. Please refer to the following methods for judgment.
There is electricity. Because of the strong electric field intensity of the working voltage: ① when the electroscope is close to the conductor for a certain distance, it will emit light (or sound light alarm), indicating that the equipment has working voltage; then, the closer the electroscope is to the electrified body, the stronger the brightness (or sound) will be. It is very important for operators to observe and master this point carefully to judge whether the equipment is electrified. ② check the electricity with insulated pull rod, with "squeaking" discharge sound; check the electricity in low-voltage circuit, if the check pen is on, use multimeter to distinguish which kind of voltage is. Put the voltage range of the multimeter on different ranges, and the measured voltage to the ground is the same value, which may be the working voltage; the larger the range (the higher the internal resistance), the higher the measured voltage, which may be electrostatic or inductive voltage;
Static electricity. The potential to ground is not high, the electric field strength is weak, and the electroscope is not bright during the electricity test. After contacting with the conductor, it sometimes emits light; however, with the electrostatic charge on the conductor passing through the electroscope → human body → earth discharge, the brightness of the electroscope becomes weak from strong to weak, and finally goes out. This phenomenon will be encountered when the power is tested on the high-voltage long cable after power failure. It is similar to static electricity, with low potential. Generally, the electroscope does not light up during electricity test.