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Guide to
| Surge Protection Devices
16
During the Initial Verification or as part of a periodic
inspection & test, the SPD should be inspected to ensure it
is operational. Any over-current protective device associated
with the SPD should be intact and should be as instructed by
the manufacturer.
There is usually some kind of visual indication on the SPD
that the device is still operational. This may be indicated by a
GREEN visual indicator window. Should this window indicate
RED then it is an indication that the device has reached its
‘End of Life’ and needs replacing. With some products, this
will involve the replacement of the device, but on many of
the products in the range, this can simply be carried out by
replacing the removable cartridge.
An insulation resistance test of 500V dc carried out with the
SPD connected will produce incorrect readings. This is due
to the SPD starting to conduct as the value of U c may have
been exceeded. This test then should be conducted without
the SPD connected. Alternatively this test can be conducted
at the reduced test voltage of 250V dc.
Inspection & Testing
“There is usually some kind of
visual indication on the SPD that
the device is still operational.
This may be indicated by a green
visual indicator window.“