Few people would dispute the fact that generators are extremely useful appliances. They supply electrical power during a power outage and prevent discontinuity of daily activities or disruption of business operations. Generators work by converting mechanical energy into electricity when local power grids are down or inaccessible.
One type of generator is called a cogeneration generator, or combined heat and power (CHP), where the production of electricity or mechanical power and thermal energy (heat and or cooling) from a single source of energy occurs simultaneously. Another similar and newer application generators are used for is called "peak shaving". This is the process of reducing the amount of energy purchased from utility companies during peak demand. This technique is used during times when electricity rates are more expensive than what it costs to operate single or multiple generators, so the generator kicks in instead of the main power source, even though it is still operational at that time.
An AC three-phase generator hosts two winding configuration types — a wye configuration, which can be solid or resistance grounded, and a delta configuration, which is ungrounded. These connection types are named after the Greek and English letter that each resembles. Since the generator function is there to provide an uninterruptible power supply, its reliability and health are crucial. It is essential that the prime mover (as shown in image 1) is maintained to move or turn the generator to produce electrical energy.
All electrical systems can experience electrical faults and abnormal electrical conditions. A large majority of electrical faults start as phase-to-ground faults, and if left undetected, can cause damage and interruption to the power supply. Generators of all kinds are not immune to these electrical faults, and therefore, early detection and accurate monitoring can mitigate damage to the generator and extend its lifecycle.