The return delay timer operates to ensure that the starting request has been permanently removed and isn’t just a short term removal. Should another start request be made during the cooling down period, the set will return on load.
If there are no starting requests at the end of the return delay timer, the load is removed from the generator to the mains supply and the cooling timer is initiated.
The cooling timer allows the set to run off load and cool sufficiently before being stopped. This is particularly important where turbo chargers are fitted to the engine.
After the cooling timer has expired, the set is stopped.