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Furse SPDs meet the performance parameters defined
in two national & European standards:
–
–
BS EN 61643-11
Surge protective devices connected to
low-voltage power systems - requirements and tests
–
–
BS EN 61643-21
Surge protective devices connected to
telecommunications and signalling networks - performance
requirements and testing methods
These parts of the BS EN 61643 standard apply for all SPDs
providing protection against lightning (direct and indirect)
and transient overvoltages.
BS EN 61643-11 covers AC mains protection, for 50/60 Hz
AC power circuits and equipment rated up to 1000 V
RMS
AC
and 1500 V DC.
BS EN 61643-21 covers telecommunications and signalling
networks with nominal system voltages up to 1000 V
RMS
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 IEC1), 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.
Technical specifications
Within BS EN 61643 there are two Technical Specifications
which provide recommendations on the selection and
installation of SPDs.
These are:
–
–
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/BS EN 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 and
performance
–– Coordination of SPDs throughout the installation (for
power and data lines) and between SPDs and RCDs or
overcurrent protective devices
Through following the guidance in these documents,
appropriate specification of SPDs to meet the installation
requirement can be achieved.
Technical reference
BS EN 61643 standard series