These requirements cover Power Control Systems (PCS) used in Distributed Energy Resource (DER) systems which include one or more power sources in addition to the primary power source, typically the utility grid. PCS-LC (load control only applications) may consist of only the utility source, or a combination of the utility source and DER sources not controlled by the PCS-LC sized per 705.12 of NFPA 70. The PCS electronically limits or controls current or power to stay within defined limits and may consist of a single device or multiple devices operating together as a system. The current or power measurement reference point(s) may be located internally to equipment or externally within the system. All elements of the PCS are intended to be installed in accordance with the National Electric Code (NEC). Section 705.13 in the 2020 edition or section 750.30 in the 2023 edition.

A PCS may be evaluated as a supplementary PCS in which a separate passive protective device (typically consisting of Overcurrent Protective Devices – OCPD) is used for the protection of service, feeder, or branch circuits. Alternatively, a PCS may also be evaluated as a branch circuit PCS to provide overcurrent protection in lieu of a separate passive protective device in accordance with UL 489 (PCS providing an active protective function in lieu of a passive protective device).

The PCS may be designed for autonomous operation or may respond to external commands or schedules provided by authorized third parties. Specific communication protocols, or other methods, used for transmitting commands or schedules are outside the scope of this Outline.

The requirements in this Outline are intended to evaluate PCS that electronically control power or current flow within power distribution equipment, or within conductors at an external location, via use of external measurement and control device(s). Such systems may be made up of generation devices (inverters, engine generators, etc.), energy storage systems, loads, load control applications (EV charging power/load management, etc.), circuit controllers, or other equipment used to manage the current flow at the point of reference. The power control function may utilize communication-based approaches and may include monitoring devices and or controllers remote from the point of control.

The PCS may include multiple external reference points used to control power or current on multiple conductors or bus bars. For example, an external point of reference may be at the point of common coupling to control power flows to or from the utility grid as well as providing overload protection of the busbars in the main service panel. External reference points may also be located to control currents within a piece of equipment or on other circuit(s) on the premises wiring.

Products and systems covered by these requirements are intended to be installed in accordance with the National Electrical Code, NFPA 70.