Megger BM80/2 Series, User Manual

Page: 12 / 89

Application Notes
11
Preventive Maintenance
The proverb ‘A stitch in time saves nine’
inspired the title of an Megger Limited booklet
on insulation testing, as it neatly sums up the
benefits of preventative maintenance. The
savings come in financial terms from costly
repairs, lost production, lost profits and in
human terms, from lives saved in the event of
dangerous electrical faults.
Regular insulation testing of electrical
equipment can help to detect deteriorating
insulation. The effects which cause insulation
to deteriorate include mechanical damage,
vibration, excessive heat or cold, dirt, oil,
moisture and localized voltage stresses - all of
which can arise on most industrial or utility
equipment.
Insulation tests are sometimes used in
isolation as absolute measures of the quality
of the insulation. This is most appropriate
when equipment is being installed and
checked for compliance with a specified ‘Pass’
level. For operational equipment the key
factors are trends in the insulation readings.
It is therefore important that records of
insulation readings are kept, relating to each
piece of equipment or ‘Asset’ in your testing
regime. Megger Limited supplies test record
cards to assist with such record keeping.
There are also a number of influences on the
insulation readings - temperature, humidity
and surface leakage for example and a range
of test techniques have been developed to
help with the interpretation of your insulation
tests.
Test Record Example