What to do if the generator set gets damp

1. Hot air method

Remove all covers from the generator set to allow moist air to escape. Use a hair dryer to blow air inward from the air inlet of the generator set. Note that there should be at least 300mm between the heat source and the winding to avoid insulation damage caused by overheating. Control the winding surface temperature. Use a thermometer to measure the winding surface and it shall not exceed 85℃, and the air inlet shall not exceed 90℃. Continue blowing and record the insulation resistance value every half hour. When the value is greater than the specified value, the drying process is completed. Remove the hair dryer, close all covers and try again.

2. Oven (furnace) baking method

Where possible, put the entire motor (it is best to disassemble the stator and rotor) into an oven (furnace) to gradually heat up and bake. The oven (furnace) should be ventilated. In order to take away the moisture in the motor, it is best to be sandwiched, with the inner layer discharging the motor and the outer layer heating. The temperature of the inner layer is maintained at 90-100°C, and there must be no open flames, smoke, dust and other flammable and corrosive gases. It is generally required to bake continuously for 8 to 18 hours, during which the insulation resistance value of the motor can be measured several times until it reaches the specified value and is stable.

3. Cold operationmethod

A generator set that has been left in a dusty or humid environment for a long time can run idling for about 10 minutes with the AVR power wire disconnected. This may be enough to dry the winding surface and increase the insulation resistance value to more than 1 megohm. The unit can resume normal operation.

4. Short circuit current drying method

First, carry out safe operation of the mechanical and electrical appliances of the diesel generator set to ensure the safety of operation on the generator set. Short-circuit the output end of the generator set through a short-circuit piece. The short-circuit piece used should be able to withstand the rated current of the generator set. Disconnect the AVR and use an external 0~24V DC power supply. Adjust the DC power supply voltage so that the current of each phase of the stator is 50-70% of the rated current. Stop the machine every 30 minutes, disconnect the external excitation power supply, and detect and record the insulation resistance value. If the insulation resistance value is greater than the specified value, remove the external DC power supply, reconnect the AVR, and retry operation. The generator set does not need to operate at the rated speed, but the speed should be kept constant to avoid temperature instability.

5. Load drying method

If only the surface is damp, load drying can be used. When dry, the generator set can first run with 50% rated current load. Then increase the value to 65%, 85%, and 100% to the rated current, and run each load level for 4 to 5 hours. During the drying process, the insulation resistance of each winding should be checked regularly. After the insulation resistance value meets the requirements, the drying can be stopped and the generator set can be put into normal trial operation.