What to Do if Diesel Generators Get Damp?

Regardless of expertise, most people are aware that diesel generators are widely used as emergency power equipment. When used outdoors, diesel generators can encounter unfavorable weather conditions. Improper handling can lead to dampness issues, especially affecting the generator's motor, significantly impacting its lifespan and operation. So, how can we solve the drying problem after the motor gets damp?

After the motor of the diesel generator gets damp, it must be promptly dried. Based on the motor's capacity and the extent of dampness, there are two common drying methods:

(1) OVEN (FURNACE) DRYING METHOD

In places with suitable conditions, gradually heat the entire motor (preferably disassembling the stator and rotor) in an oven (furnace) with ventilation. This aims to remove moisture from the motor. It's best to use a double-layered oven (furnace) with the motor in the inner layer and heat applied to the outer layer. Maintain the inner layer's temperature at 90-100°C, ensuring no open flames, smoke, or other flammable or corrosive gases are present. Typically, continuous baking for 8-18 hours is required, periodically measuring the motor's insulation resistance until it reaches the specified and stable value.

(2) STEADY-STATE SHORT-CIRCUIT CURRENT METHOD

After an AC generator gets damp, short-circuit the three phases inside the terminal box. Then, increase the generator's speed to the set speed and maintain it. Adjust the excitation current to achieve a stator short-circuit current of 50%-70% of the rated current, maintaining it for 4-5 hours. Then, increase the excitation current to achieve a short-circuit current of 80%-100% of the rated value, keeping the coil temperature below 85◦C. Measure the coil's insulation resistance and temperature every 30 minutes until the insulation resistance reaches the specified and stable value.

With the enhanced capabilities of diesel generator sets, the requirements for their cooling medium have also increased. So, how should cooling water be selected?

During the operation of a diesel engine, the normal temperature of the cooling water should be maintained between 75-90°C. At this temperature, the diesel engine can produce maximum power, the fuel consumption will approach an economical state, and the wear and tear on components will be lower. If the cooling water temperature is too high or too low, or if the thermostat is removed, the functionality of the cooling system might reduce or be lost. While a diesel engine operates, the combustion of fuel generates substantial heat, with gas temperatures in the cylinder reaching 1800-2000°C. However, only 30%-40% of the heat produced is converted to mechanical energy, with about 20%-25% being dissipated by the cooling system. If the cooling system malfunctions, with excessively high or low temperatures, it can not only affect the diesel engine's normal operation but also cause faults and accidents.