BS EN 61643-11 covers AC mains protection, for 50/60 Hz AC power circuits and equipment rated up to 1000 VRMS AC and 1500 V DC.
BS EN 61643-21 covers telecommunications and signalling networks with nominal system voltages up to 1000 VRMS AC and 1500 V DC.
Within these parts to the standard is defined:
The electrical requirements for SPDs, including voltage protection and current limiting levels, status indication and minimum test performance
The mechanical requirements for SPDs, to ensure an appropriate quality of connection, and mechanical stability when mounted
The safety performance of the SPD, including its mechanical strength and its ability to withstand heat, overstress and insulation resistance
The standard establishes the importance of testing SPDs to determine their electrical, mechanical and safety performance.
Electrical tests include impulse durability, current limiting, and transmission tests.
Mechanical and safety tests establish levels of protection against direct contact, water, impact, the SPD installed environment etc.
For voltage and current limiting performance, an SPD is tested according to its Type (or Class to IEC), which defines the level of lightning current or transient overvoltage it is expected to limit/divert away from sensitive equipment.
Tests include Class I impulse current, Class I & II nominal discharge current, Class I & II voltage impulse and Class III combination wave tests for SPDs installed on power lines, and Class D (high energy), C (fast rate of rise), and B (slow rate of rise) for those on data, signal and telecoms lines.
SPDs are tested with the connections or terminations following manufacturer’s instructions, as per the expected SPD installation.
Measurements are taken at the connectors/terminals. Three samples of an SPD are tested and all must pass before approval is granted.
SPDs which have been tested to BS EN 61643 should be suitably labelled and marked, to include the relevant performance data for their application.
Within BS EN 61643 there are two Technical Specifications which provide recommendations on the selection and installation of SPDs.
DD CLC/TS 61643-12 Surge protective devices connected to low-voltage power systems – selection and application principles
DD CLC/TS 61643-22 Surge protective devices connected to telecommunications and signalling networks – selection and application principles
These Technical Specifications should be used with BS EN 61643-11 and BS EN 61643-21 respectively.
Each Technical Specification provides information and guidance on:
Risk assessment and evaluating the need for SPDs in low-voltage systems, with reference to IEC 62305 Lightning protection standard and IEC 60364 Electrical installations for buildings
Important characteristics of an SPD (e.g. voltage protection level) in conjunction with the protection needs of equipment (i.e. its impulse withstand or impulse immunity)
Selection of SPDs considering the entire installation environment, including their classification, function & performance
Coordination of SPDs throughout the installation (for power and data lines) and between SPDs and RCDs or over-current protective devices
Through following the guidance in these documents, the appropriate specification of SPDs to meet the installation requirement can be achieved.
Type 1, 2, or 3 SPDs to BS EN/EN 61643-11 are comparable to Class I, Class II and Class III SPDs to IEC 61643-11 respectively.
Awareness, that transient surges are the main influencing factor of the MTBF (Mean Time Between Failures) of systems and equipment, is driving all manufacturers in the area of surge protection to continuously develop new overvoltage protective devices with increasing features and in compliance with the actual international & european standards. The following is a list of the key standards involved: