The dielectric strength test of insulating oil is a commonly conducted test in the power industry, and the dielectric strength tester of insulating oil is a specially designed instrument for this test. In order to do this experiment well, we must understand its testing method and precautions.
Test method for Dielectric strength of insulating oil:
1. The experimental operation steps and methods shall be carried out according to the instrument manual, where the boosting speed is set to 2-3kV/s, the static time before * boosting is set to 10-15min, the stirring time is set to 1min, and the interval time between the six boosting processes is set to 3-5 minutes.
2. On the measuring device, the instrument will apply a 50Hz AC voltage to both ends of the electrode containing the sample after the set stirring and rest time. The voltage will rise uniformly from zero according to the set boosting speed to the value at which the sample undergoes breakdown. The breakdown voltage is the voltage reached when a spark occurs between the electrodes, regardless of whether the spark is instantaneous or constant.
3. If manual pressure is used, after breakdown of the sample, gently stir the prepared Glass rod or stainless steel rod between the electrodes to remove the free carbon generated by breakdown. When stirring, try to avoid the generation of air bubbles as much as possible. Wait for 1 minute after the air bubbles disappear, and then apply a second voltage. If it is impossible to observe the disappearance of air bubbles, the breakdown voltage test must be conducted again after 5 minutes.
Precautions for Dielectric strength test of insulating oil:
1. The Dielectric strength test is quite sensitive to the slight pollution of the sample, and it is easy to absorb moisture when sampling. Therefore, the clean and dry sampler shall be used for sampling in strict accordance with the sampling method of power oil. The oil test must be carried out in a laboratory for a period of time without damaging the original storage seal, and the cap test can only be carried out when the oil temperature and room temperature are similar (arbitration test should be conducted between 15 and 20 ℃). Before uncovering, gently shake the test oil to mix the internal impurities evenly, but no bubbles should be generated.
2. When pouring out the original test oil, be sure to use dry, clean, and pollution-free forceps or magnetic glass rods to clamp out the mixing slurry. Wash the oil cup 2-3 times with a test oil. When washing, pour the test oil off the electrode plate and gently shake it left and right to moisten the cup wall. When washing the oil cup, use tweezers to hold the stirring slurry and also rinse it in the lubricating solution.
3. Before boosting operation, it is necessary to carefully check the connection of the circuit (at each connection point and plug) and the grounding of the ground wire.
4. The test shall be conducted under conditions of humidity not exceeding 75%. Only when the temperature of the cooling oil is similar to room temperature can the test be conducted.
5. When injecting oil into the oil cup for testing, it should slowly flow down the inner wall of the oil cup to avoid the formation of air bubbles. During operation, it is not allowed to touch the electrode, the inside of the oil cup, and the oil test with hands to prevent pollution to the oil test. After the oil test is loaded into the oil cup, apply * times of voltage as soon as possible after ensuring that there are no more air bubbles in the sample (later than 10 minutes after oil loading).
The method and precautions of using insulating oil Dielectric strength tester to conduct insulating oil Dielectric strength test are things that must be known before the test