How to prevent film capacitor failure? What should I pay attention to?

After long-term use, film capacitors will have some problems. Understanding the causes and preventive measures of capacitor failures can effectively increase the service life of film capacitors.

1. Deal with abnormal operating conditions in time. If abnormal conditions such as bulging, joint heating, and severe oil leakage (leakage) are found in the parallel capacitor during operation, it must be taken out of operation. For vicious accidents such as fuel injection, fire, explosion, etc., power outage inspection should be carried out immediately, and the cause of the accident should be found and dealt with before it can be replaced with a new capacitor to continue operation.

2. Strictly control the operating voltage. The operating voltage of the parallel capacitor must be strictly controlled within the allowable range. That is, the long-term operating voltage of the parallel capacitor shall not be greater than 10% of its rated voltage value. If the operating voltage is too high, the service life of the capacitor will be greatly shortened. As the operating voltage increases, the dielectric loss of the parallel capacitor will increase, which will increase the temperature of the capacitor, accelerate the aging speed of the capacitor insulation, and cause premature aging, breakdown and damage to the insulation in the capacitor. In addition, under the action of excessively high operating voltage, the insulating medium inside the capacitor will undergo local aging. The higher the voltage, the faster the aging and the shorter the life.

3. Fuse protection should be installed for each single capacitor. The rated current of the fuse shall not be greater than 1.3 times of the rated current of the capacitor to be protected, so as to avoid failure of a certain capacitor due to failure Removal in time caused group explosion accidents.

4. Correctly select the throw (cut) switch and disconnect the parallel capacitor, due to the arc action between the static and moving contacts of the switch, it will cause the operating overvoltage, except that the capacity of the throw (cut) switch is required to be selected more than the parallel connection In addition to the capacity of the capacitor bank is about 35% larger, it must also be a circuit breaker with high insulation recovery strength between the contacts, low arc reignition, and good arc extinguishing performance.

5. Control the operating temperature. Under normal circumstances, it is generally required that the temperature of the hottest spot of the shunt capacitor housing should not be greater than 60°C. Otherwise, the cause must be found out and processed.

6. Strengthen patrols, inspections, and maintenance of parallel capacitors should be checked regularly, at least once a quarter, mainly to check whether there is dust and other dirt in the capacitor shell, porcelain bushing, mounting bracket, etc., and clean it carefully . When checking, pay special attention to whether the connection of each connection point is firm, whether it is loose; whether the shell is bulging, seeping (leaking) oil, etc. If the above phenomena are found, the capacitor must be taken out of operation and handled properly.

7. It is also important to choose a good film capacitor manufacturer, such as timely handling of problems, product quality, whether the price is appropriate, and so on.