BSI PD IEC/TS 62257-9-1:2016

Decentralized Rural Electrification Systems (DRES) are designed to supply electric power for sites which are not connected to a large interconnected system, or a national grid, in order to meet basic needs.

The majority of these sites are:

• isolated dwellings;
• village houses;
• community services (public lighting, pumping, health centres, places of worship or cultural activities, administrative buildings, etc.);
• economic activities (workshops, micro-industry, etc.).

The DRESs fall into the following three categories:

• process electrification systems (for example, for pumping);
• individual electrification systems (IES) for single users;
• collective electrification systems (CES) for multiple users.

Process or individual electrification systems exclusively consist of two subsystems:

• an electric energy generation subsystem;
• the user's electrical installation.

Collective electrification systems, however, consist of three subsystems:

• an electric energy generation subsystem;
• a distribution subsystem, also called microgrid;
• user’s electrical installations including interface equipment between the installations and the microgrid.

This technical specification applies to a micropower plant which is the electric energy generation subsystem associated with a decentralized rural electrification system.

It provides general requirements for the design, erection and operation of micropower plants and general requirements to ensure the safety of persons and property.

The micropower plants covered by this specification are low-voltage a.c., three-phase or single-phase, with rated capacity less than, or equal to, 100 kVA. The rated capacity is at the electrical output of the micropower plant, that is, the upstream terminals of the main switch between the micropower plant and the microgrid. They do not include voltage transformation.

The voltage levels covered under this specification are:

• the 240 V 1-Ø/415 V 3-Ø, the 230 V 1-Ø/400 V 3-Ø, the 220 V 1-Ø/380 V 3-Ø, and the 120 V 1-Ø/208 V 3-Ø systems at 60 Hz or 50 Hz; or obeyed by local code.
• the ELV (less than 120 V) d.c. systems.

The requirements cover “centralized” micropower plants for application in:

• process electrification;
• individual electrification systems and collective electrification systems.

It does not apply to distributed generation on microgrids.