This International Standard applies to Source Switching Equipment, hereafter referred to as SSE(s), for household and similar uses, primarily intended to be used for Energy Efficiency purposes with local production and/or storage of energy.
This standard has been drafted following principles of:
- IEC guides 118 and 119 for Energy Efficiency;
- IEC guide 110 for safety.
SSEs are intended to be installed in low voltage prosumer electrical installations (PEI) to deliver the electrical energy:
- either to current-using equipment (direct feeding mode or island mode);
- or to the grid (reverse feeding mode).
SSEs are intended to select and/or combine two power sources (e.g. selected among grid, local power source, storage units) within an Electrical Energy Management system (EEMS). SSEs may also be used for backup supply.
NOTE SSEs capable to select more than two sources are under consideration.
SSEs are part of the fixed electrical installation.
This standard applies to SSEs for operation in:
- AC single or multiphase circuits with rated voltages not exceeding 440 V AC, frequencies of 50 Hz, 60 Hz or 50/60 Hz and rated currents not exceeding 125 A. They are intended to be used in installations with prospective short circuit current not exceeding 25 000 A, or
- DC circuits. SSE for DC circuits are under consideration (next edition).
SSEs may be operated:
- manually (M-SSE), or
- remotely (R-SSE), or
- automatically (A-SSE), or
- a combination of the above methods of operation, e.g. manual and remote.
SSEs are constructed either as Combined-SSEs (C-SSEs, based on dedicated products suc as circuit breakers, switches or contactors) or Non-Combined SSEs (NC-SSEs).
SSEs are intended for use in circuits where protection against electrical shock and over-current according to IEC 60364 is provided, unless the SSE already contains such protective function.
SSEs are normally installed by instructed persons (IEC 60050-195:1998, 195-04-02) or skilled persons (IEC 60050-195:1998, 195-04-01). SSEs are normally used by ordinary persons (IEC 60005-195:1998, 195-04-03) and do not require maintenance.
The requirements of this standard apply for standard environmental 420 conditions as given in clause 7. They are applicable to SSEs intended for use in an environment with pollution degree 2 and overvoltage categories III according to IEC 60664-1:2020. SSEs have at least a degree of protection IP 20 according to IEC 60529. Additional requirements may be necessary for devices used in locations having more severe environmental conditions.
SSEs do not, by their nature, provide an isolation function nor the overcurrent protection. However, isolation and overcurrent protection functions as covered by relevant product standards may be provided by Combined SSEs.
In some countries, it is not permitted to have synchronization of local sources with the grid for particular grid conditions, e.g. when fluctuations of the grid voltage or frequency are outside the tolerance limits.
This document does not apply to transfer switching equipment (TSE) intended to be used by skilled persons, as covered by IEC 60947-6-1:2021.