Text preview for : Preventive Maintenance Test with Insulation Resistance Test - Application Note 5991-4026EN c20141010 part of
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Preventive Maintenance Test
with Insulation Resistance Test
Application Note
Introduction
Preventive maintenance is a predetermined task performed based on a schedule and its objective is to
keep equipment in good condition to avoid breakdowns.
Insulation resistance testing is commonly performed as part of electrical testing in a preventive
maintenance program for rotating machines, cables, switches, transformers, and electrical machinery
where insulating integrity is needed. Insulation resistance testing in the preventive maintenance pro-
gram helps identify potential electrical issues to reduce unpredictable, premature equipment repairs
and replacement costs.
With properly scheduled monitoring and data collection, this testing can be very useful in analyzing
and predicting the current and future behavior of equipment. Early problem detection helps avoid
major repairs, resulting in cost savings when compared to a run-to-failure maintenance practice.
Preventive maintenance has the added benefit of allowing time to order any necessary parts and
schedule appropriate resources.
This application note describes the insulation resistance testing method used for preventive
maintenance activities.
2
What is Insulation Resistance Testing?
Insulation resistance testing is carried out by applying a constant voltage to the equipment
under test while measuring the any flowing current. High DC voltages are used causing a small
current to flow through the insulator surface. The total current consists of three components:
capacitance charging current, absorption current, and leakage current (refer to Figure 1.)