Generation Deactivations Generator deactivations can alter power flows that may yield violations of established transmission system reliability criteria. Therefore system upgrades may be required to correct any identified reliability violation, in many areas of PJM. Visit the Learning Center site to learn about the steps PJM takes to keep the grid stable when power plants retire. The list of deactivations is typically updated within 24 business hours of notification from the generator. If a deactivation is not shown, PJM has not been notified of the deactivation.