It was found that the dc power monitor could not be automatically equalized and the floating charge could be converted to equalized charge only after manual reset.
1. Cause analysis:
According to the inspection results, the reason why there is no dc output after the ac power loss is that there is an open circuit inside one battery in each battery, resulting in no output of the whole battery.
(1) because the upper cover of changshui substation battery was cracked during operation, the battery terminal voltage was measured and considered normal, and the battery was not removed or replaced in time. The battery discharged hydrogen, oxygen, water vapor and acid fog during operation, and the operation time was not long because of internal drying failure and open circuit;
(2) since the charger cannot be automatically converted to uniform charging, the battery has been undercharged under floating charging state. As the vacuum circuit breaker of changshuicurrent substation is an electromagnetic operating mechanism, the battery will discharge in large current during closing operation, and the negative electrode will gradually become passivated during long-time operation, resulting in battery damage and open circuit.
(3) when dealing with the cracking defect of the upper cover of the 17th battery of the battery set, no removal and replacement measures were taken. During the inspection, the battery was not charged and discharged in accordance with the regulations, causing the hidden danger of the dc screen not to be found in time until there was no output fault of the dc power battery;
(4) there are deficiencies in the daily testing methods of traction substation battery. The test is conducted when the battery is disconnected from the charging and discharging circuit, rather than after a certain discharge of the battery, resulting in the failure to timely find the defects of open circuit in the battery during daily testing.
2. Lessons to be learned:
(1) all batteries should be tested once a month. During the test, the ac power of the charger must be turned off. After discharging the battery for 30 minutes with load, the battery will be tested again.
(2) according to the battery maintenance process, every two years by the battery for a check charge-discharge test, to find the hidden defects in the battery;
