Faults Caused by Oxidation of Batteries in Daewoo Generator Sets

A South Korean Daewoo generator set has a rated power of 50kW for a diesel electromechanical station. JDK is the main power switch (grounding switch), section is the starting power switch, SA1 is the ignition switch, M and Q are the starting motor and electromagnetic switch coils, TJ is a DC relay. The normal starting process involves the main power switch JDK on the platform and the starting power switch QF. Turn the ignition switch SA1 to. Starting the "position", at this time, the DC relay ZJ coil is energized, its normally open contact is closed, and the electromagnetic switch coil Q is energized to connect the starting motor M, starting the Korean Daewoo generator set to drive the diesel engine to start.

After the power station connected the starting circuit to supply power to the starting motor, a fixed frequency "da da da" sound was heard around the starting motor of the Korean Daewoo generator set. The starting motor of the Korean Daewoo generator set did not operate, and the diesel engine could not start.

When the starting key SA1 is opened and started, the battery voltage is applied to both ends of the starting relay coil. The normally open contact of the starting relay is closed, and the motor of the Korean Daewoo generator set is energized. The entire circuit generates a large current instantly. At this point, if the resistance value of a certain point in the starting circuit is high, most of the voltage will drop at that point, causing the voltage at both ends of the starting relay coil to decrease. When the pull-in voltage is lower than the relay, the normally open contact will open, the entire starting circuit will be powered off, the current will disappear, and there will be no voltage drop at this point; The starting power voltage is all applied to both ends of the starting relay coil. Repeat the process just now, and the circuit will open and close in a cycle, resulting in a continuous "click" sound from the starting relay.

In order to find the point that affects the circuit, we gradually checked the components and their wiring in the circuit, ensuring that the components are intact and the wiring is reliable; Using a battery tester to test the battery level, it was found that there were white fungi around the contact between the battery clip and the battery terminal when the battery was fully charged. At the same time, it was found that there were black oxides around the terminal.

Based on the analysis of the above phenomena, it is preliminarily determined that the contact fault of the battery terminal caused the diesel engine of the Korean Daewoo generator set to fail to start. Because in cold and humid areas in the south, electrical components and various wiring terminals are prone to forming a layer of oxide film due to fungal corrosion. This layer of oxide film has a high resistance. When the circuit is connected to generate current, a large voltage drop is generated at this end, causing the voltage at both ends of the starting contactor coil to be lower than the pull-in voltage, causing the diesel engine of the Korean Daewoo generator set to be unable to start.

Due to fungal corrosion on the surface of the terminals of the Korean Daewoo generating set, an oxide film is formed. Simply remove the oxide film. First, clean the battery terminals and battery clips with boiling water until they show the true color of the material. Then, wipe them clean with a towel, reconnect the battery clips, and start the diesel engine of the Korean Daewoo generator set smoothly.

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