Load management

Three different functions

Sequencing staggers the connection of loads so that several large starts do not occur together. Shedding removes selected loads when a controller detects an overload or another defined condition. Lockout keeps a designated load unavailable throughout generator operation. These functions can be combined, but they serve different purposes. [1]

Manual management relies on an operator choosing which equipment to use. Automatic systems use compatible control equipment and defined priorities. A plan based on voluntary behavior has different reliability from an installed system that enforces the same restrictions.

Priorities and recovery

Priorities identify which services should remain available first and which can tolerate interruption. For example, a designer might assign a discretionary heating load a lower priority than refrigeration. The actual choices depend on the building’s occupants, equipment, and required services.

Loads also need a controlled return. Reconnecting every shed load at once can recreate the overload or starting event that caused the interruption. Manufacturer systems may include recovery delays and staggered priority intervals. Those timings and detection methods belong to the particular control system; they should not be assumed identical across products. [1]

Sizing with management

A managed system is sized against the combinations of loads the controls permit. Each allowed combination still needs enough running capacity and acceptable starting performance. If two appliances share a priority and may return together, their combined demand must be assessed. [2]

Load management cannot increase the generator’s fuel-specific rating, compensate for an inadequate fuel supply, or guarantee that an individual difficult motor will start. It also has practical consequences: a shed appliance may be unavailable for part of an outage. Document the allowed loads, recovery behavior, and user expectations as part of the design.

A qualified installer should select compatible transfer and control equipment and verify the configured behavior. The useful outcome is a system with understandable service limits, rather than a wattage calculation that silently depends on loads never overlapping.