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interruptions and repetitive damage
leading eventually to failure. Causes
can be external events such as
lightning or grid switching or
internally located motor and relay
switching.
Surges rise to dangerous voltage
levels very quickly, often within
nanoseconds. Fuses and circuit
breakers cannot react quickly
enough to prevent damage.
Alternative approaches are therefore
necessary to add surge protection
to any overcurrent measures
already in place. The most widely-
used components are spark gaps
and varistors. Spark gaps, which
have a long lifetime and can absorb
high amounts of energy, typically
require some level of activation
energy, whereas varistors are very
fast without the need for energy to
trigger.
It is recommended to install at least
one Surge Protection device (SPD)
per distribution cabinet, one per
sensitive device and one per sensor
line that leaves a building. The cost
of SPDs is usually a tiny fraction
compared to the damage it helps to
prevent.
Conclusion
It is clear to see that there are many
different types of fault conditions and
suitable circuit protection methods.
The ultimate success of any circuit
protection strategy to increase
uptime and improve operator safety
depends very much on choosing
the right partner. Circuit breakers,
fuses and other devices rarely work
best as standalone items. They are
usually designed into hierarchical
power systems where responsibility
for protection is shared among
components according to their
position in the overall layout. It
therefore makes sense to source
all these elements from a single,
preferably global, partner that can
guarantee their efficacy in working
together, and can advise on building
a balanced solution.
Machine builders can bring a real
competitive advantage to their
offering if they can find a circuit
protection component partner
with sufficient breadth and depth
of stock, matched by equally
comprehensive global technical
and logistics support. The issue
of circuit protection can become a
sales advantage instead of a design
problem.
New-Tech Magazine Europe l 59