• Use a dry, lint-free cloth or compressed air to remove dust and debris from the stator and rotor windings. A vacuum cleaner may be necessary for stubborn deposits. Degreasing liquids can clean windings and terminals.
• Carefully examine the windings and terminals for signs of damage (cracks, abrasion) or overheating.
• Ensure that the air passages are clean and unobstructed to allow for proper cooling.
• Check the condition and oil level of the bearings.
• Measure the air gap between the rotor and stator using a plastic feeler gauge (the specified gap is 2-3mm).
• Measure the insulation resistance between the stator and earth, and between stator phases. Remember to disconnect any electronic components that could be damaged by the high voltage of the insulation test.
• Inspect the rotor slip rings and carbon brushes (if fitted) for even wear and the absence of dampness.
• Keep the generator excitation transformer, AVR components, and rotating diodes clean and free of dirt. Use special contact grease on diode connections to prevent electrolytic action.
• Bake the windings at a temperature not exceeding 43°C to eliminate moisture.

When two A.C. generators are running in parallel, they share the total load based on their power settings and capacities. Both generators operate at the same frequency, and their outputs remain synchronized. However, if the driving power of one generator (e.g., Generator A) suddenly fails, it can no longer supply active power to the load. In this case, Generator A will begin to draw power from the other generator (Generator B) to keep its rotor spinning. This condition, known as "motorizing," occurs because the failed generator essentially acts as a motor.

This situation is hazardous because the affected generator (Generator A) will consume power instead of generating it, leading to increased current flow in its windings. This excessive current can cause overheating and damage to the windings and other components. Additionally, the load previously shared by both generators will now be entirely shifted to Generator B. If Generator B is not designed to handle the full load, it may trip due to overloading, potentially leading to a complete blackout of the system.

To prevent such dangerous conditions, a reverse power relay is installed in each generator. This relay continuously monitors the direction of power flow. If it detects that power is flowing into the generator (indicating reverse power), the relay immediately trips the generator, disconnecting it from the system. The reverse power trip is an essential safety feature that protects the generator from damage. However, even with this protection, the sudden transfer of load to the remaining generator can still cause voltage and frequency fluctuations, which must be managed to maintain reliable operation.