Common faults and countermeasures of alkaline storage batteries

Alkaline batteries are DC power sources widely used in power plants and substations to provide control, control, signal, protection, and accident lighting for electrical equipment. It has high discharge rate, relatively simple charge and discharge maintenance, no need for special battery room, long service life (about 10 to 15 years), relatively low price, low pollution and so on. However, due to improper charging and discharging methods and battery quality, the DC power supply capacity is degraded, which makes the circuit breaker difficult to jump. This article gives an analysis of the common faults and gives corresponding treatments.



1 The voltage-dispersive large-alkaline battery between the single cells (the sintering type is more) has a float voltage of 1.35V to 1.45V ± 0.05V. When it exceeds this range, the dispersion is large. The phenomenon can be divided into the following symptoms.
1.1 The voltage dispersion of all single cells is mainly caused by insufficient battery charging. The reasons are as follows:
1) insufficient charging at the time of initial charging;
2) The float voltage is low;
3) Balanced charging is not enough;
4) Resuming charging after discharge is not enough.
It is found that the float voltage should be adjusted in time. For the lack of charging due to initial charging, the method of repeated charging and discharging can be used to make the capacity reach the specified value.
1.2 The voltage of a few batteries is extremely low. In the inspection of the battery, it is found that a certain battery voltage is extremely low. It should be checked whether the polarity is reversed. If it is, it should be removed from the circuit in time; if not, it may be caused by a partial short circuit. The so-called partial short circuit constitutes a tiny short circuit between the anode and cathode plates of the battery. Since the voltage caused by the partial short circuit is too low, it can be recovered by means of balanced charging. If it cannot be recovered, the battery should be replaced.
1.3 The battery termination period is getting closer and the dispersion is getting larger. Due to the increase in the service life, the difference in self-discharge of alkaline storage batteries is getting bigger and bigger. At this time, the voltage dispersion is measured more and more. At this time, the battery measurement should be increased. The number of times and the number of times of equalization charging are appropriately increased to compensate for the difference in self-discharge of the battery.
2 Reduction of discharge capacity In use, the discharge capacity of the battery is often found to be reduced, which is mainly caused by the following factors.
2.1 Undercharged Undercharged performance is as follows:
1) The floating charge voltage is too low and long-term use. The phenomenon that the battery capacity has decreased after one year of operation in a power station has been investigated. The check is due to the inaccurate indication of the float charge gauge, which causes the float charge voltage to be too low for long-term use. After resuming the capacity recovery, the battery is used normally.
2) Frequent charging and discharging, but insufficiently reducing the discharge capacity when charging is resumed, and the battery may have insufficient or uneven floating charge capacity for a long period of time, which is caused by a large electrochemical change of the active material. In the activation charge and discharge, if the current is not well grasped, the capacity is easily reduced, especially after a charge and discharge cycle.
3) No equalization charging is performed. Balanced charging is a supplementary charge to the battery after using the battery after an accident (no AC floating charge). If the balanced charging is not performed, the plate will be passivated and the battery capacity will be reduced. The battery will be replaced after each power failure in a substation. Placed in the floating state, long-term use, resulting in reduced capacity, so each unit should pay attention to balanced charging, timely replenishment.
After the capacity reduction occurs, the cause should be identified and the fault should be eliminated. At the same time, the battery should be repeatedly charged and discharged in depth to fully activate the chemical reaction of the battery, and the effect can be better if the electrolyte is replaced.
2.2 Reasons for the increase in capacity of potassium carbonate In addition to insufficient charging, there is also an increase in natural potassium carbonate due to the reaction of the electrolyte of the battery with carbon dioxide in the air or with the electrolytic oxidation of the battery element. When the content of potassium carbonate in the electrolyte increases, the specific gravity of the electrolyte rises, the internal resistance of the battery increases, and the discharge voltage drops, which may adversely affect the large electric discharge (such as oil switch jumping, charging and discharging). . It also causes the cadmium, which is the main component in the anode, to crystallize during the charging and discharging process, tending to be coarse, and the effective surface area is reduced. At the same time, since the reduction of hydroxide ions (OH-) also stops the discharge reaction, these will cause high current at high current rate. The plate voltage is lowered and the battery capacity is insufficient under discharge. Therefore, the electrolyte should be tested regularly. If there is no detection means or the amount of electrolyte required is small, regular replacement of the electrolyte can be used to solve such problems. In the external installation, we recommend that the operating unit replace the electrolyte for 2 to 3 years, and cooperate with a deep charge and discharge, the effect is good.
3 The electrolyte distilled water is not pure in the installation, but also encounters the electrolyte is not pure, resulting in reduced battery capacity, voltage drop and battery leakage such as leakage of the extreme parts, all of which are properly handled.
Some of the faults are caused by the charging and discharging device. For example, a power station in Altay has failed to be discovered due to the automatic conversion of the balanced charging and floating charging. The operating staff failed to find out that the long-term operation is in the floating state, and the capacity is reduced a lot. In the gate test, remote closing is no longer possible. After electrolyte replacement and deep charge and discharge, the capacity is restored.
Alkaline batteries can be used for years of design if properly maintained and used properly. The operation and inspection staff should observe various phenomena at any time and check and handle them in time to make the DC system perform its proper function.