Medium Voltage Cable Testing Procedure

Connect c1 and p1 of the test set to one end of the cable shield.

Medium voltage cable testing procedure.

The test measures the insu lation resistance between the phases and or between phase and ground. Insulation resistance testing is a non destructive test procedure. When comparing this figure to power frequency ac or 0 1 hz vlf cos rectangular the tree growth rate is only 2 2 5 9 and 3 4 7 8 mm h. N medium voltage cable technician certification.

Periodic off line partial discharge testing at very low frequencies vlf is a diagnostic method for monitoring the insulation degradation of medium voltage cable. Damped alternating current voltages are generated by charging the test object to a predetermined voltage level and then discharging its capacitance through a suitable. If the high voltage test is made in dc it is then combined with insulation. Includes testing procedures.

If the high voltage test is made in ac it is then this is then more stressful for the sample and made according to the sketch below. Making them useful especially for field testing where transport and space can be issues. Using a four point low resistance ohmmeter connect both c1 and p1 of the test set to one end of the cable shield. A typical 15 kv medium voltage cable in usa has an insulation thickness of 0 22 5 6 mm and therefore during a vlf test time of 30 minutes all defects within the cable should grow to failure.

Raise the conductor to the specified maximum test voltage and hold for 15 minutes. Dac voltage testing is one of the alternative methods of ac voltage testing and is applicable for a broad range of medium voltage high voltage and extra high voltage cables. Certification cable testing diagnostics medium voltage. Refer to table 100 6.

If performed by means of direct voltage dc reduce the test set potential to zero and measure residual voltage at discrete. We need to apply 1 414 times 11 1 414 15545 volts dc of voltage between phase to phase or between phase to earth. Inspection and test procedures 7 3 3 cables medium and high voltage cont optional page 3 ats 2003 8. The high voltage test also called dielectric strength test or hipot test can be made in ac or dc.

After more than 50 years avo training remains a global leader in safety and maintenance training for the electrical industry. An arbitrary test voltage level could result in a cable failure in a circuit that would otherwise have provided long trouble free service at normal operating ac voltage. Perform a shield continuity tests on each power cable. Vlf systems are advantageous in that they can be manufactured to be small and lightweight.

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