Application Notes
Preventive Maintenance
The proverb ‘A stitch in time saves nine’ inspired the title of
an
AVO
INTERNATIONAL
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.
AVO
INTERNATIONAL
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.
AVO INTERNATIONAL
Insulation Test Record
Equipment................................
N
o.
................. Rating..............
Location ...................................
Date installed ........................
0.1
1
10
100
1000
10000
100000
1000000
Date
M
Ω
Test Record Example
15
