Application Notes
Preventive Maintenance
The proverb 'A stitch in time saves nine' inspired the title
of a 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
localised 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.
10
INSULATION TEST RECORD
Equipment
N
o
Location
Test Record Example
Rating
Date Installed