What are the preventive measures for common faults of intermediate frequency electric furnace capacit
Author：admin Time：2018-10-19 09:16
Strengthen inspection, inspection and maintenance：
Parallel capacitors should be checked periodically for power failure, mainly for capacitor housing, porcelain bushing and pile head screw. When checking, special attention should be paid to whether the connection of each connection point is firm, whether it is loose, whether the shell is bulging, oil leakage, etc. If the above phenomena are found, the capacitor must be discharged and handled properly.
2. control voltage: the operating voltage of the shunt capacitor must be strictly controlled within the allowable range. It should not exceed 10% of its rated voltage. If the operating voltage is too high, the service life of the capacitor will be greatly shortened. With the increase of operating voltage, the dielectric loss of shunt capacitor will increase, the temperature of shunt capacitor will rise, the aging speed of capacitor insulation will be accelerated, and the insulation in shunt capacitor will be damaged by premature aging and breakdown. In addition, under the action of excessive operating voltage, the insulation inside the capacitor will undergo local aging. The higher the voltage, the faster the aging and the shorter the life.
3. Choose the switch correctly: When disconnecting the shunt capacitor, the switching overvoltage will occur because of the arc action between the static and dynamic contacts of the switch. In addition to the capacity of switching (switching) is required to be 35% larger than that of shunt capacitor banks, the insulation recovery strength between contacts must be high, and the arc reburning must be high. Small circuit breaker with good arc extinguishing performance.
4. preventing harmonics：There are many harmonic sources in the power grid of medium frequency furnace. If the harmonic is too large at the grid point where the shunt capacitor is set up, if the shunt capacitor is directly put into the power grid, the harmonic in the power grid of medium frequency furnace will be larger, which will pose a great threat to the safety of the shunt capacitor of medium frequency furnace. By installing series reactor, the occurrence of harmonic component and inrush current can be effectively suppressed, and the safe operation of shunt capacitor can be guaranteed. Where conditions permit, the harmonic component at the installation of shunt capacitors should be tested beforehand, and the capacitance of series reactors to be installed should be determined according to the test results.
5. Control operation temperature: In normal environment, it is generally required that the temperature of the hottest spot of shunt capacitor shell should not exceed 60, otherwise, the cause must be found out and treated.