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Checklist for Insulation Tests
4
Test Procedure
4.1
Is an Automatic Controller Installed in the Tester?
If the tester does not have an automatic controller, the test voltage set under
no-load can drop to extremely low values due to capacitor effect, creeping
discharges and pipe moisture.
The fact that individual flaws may nevertheless be indicated does not mean
that all the flaws are actually being detected. ELMED Isotest testers have an
integral sphere gap and an automatic controller which hold the preset voltage
constant even under load.
4.2
Are the Test Electrodes in Order as per DIN 30 672, Section 5.5.5?
4.2.1 Has the spiral electrode appropriate to the pipe diameter been selected?
The electrode must be flush on all sides. It must not sag, as this will result in
incorrect measurements.
4.2.2 Has the test brush appropriate to the pipe diameter been selected?
The electrode must be in contact with the pipe over the full brush surface.
Gaps between pipe and brush will result in incorrect measurements.
4.2.3 Are the brush electrodes solid brushes?
Thanks to their higher stability, solid brushes with continuous brush cover can
ensure the necessary full contact with the pipe surface over a long period of
operation. Electrodes with only individual bunches of bristles can easily result
in incorrect measurements due to bent bristles.
4.2.4 Are the brushes still in order?
Even the best brushes wear after a time. Worn or severely bent bristles lead
to the above-mentioned gaps and thus to incorrect measurements. Install new
brushes!
4.2.5 Do not use brush electrodes with plastic guide wheels!
Non-conductive plastic guide wheels can mask point flaws and thus result in
incorrect measurements.
