High voltage insulation diagnostics

Electrical Power & Protection

January 2012 Electrical Power & Protection

Megger’s new DELTA4000 series insulation diagnostic test sets offer fully automatic power factor/tan delta measurement and tip-up testing. They feature tough yet lightweight construction and are designed to work reliably in high interference areas like substation switchyards. They also have facilities for full manual control, including the ability to vary the applied voltage up to 12 kV during testing to cater for special requirements.

Accurate and dependable temperature correction, based on the actual condition of the test object, can be applied to results using a novel and patented technique. This works with data acquired from a separate dynamic frequency response (DFR) test. Automatic detection of non-linear response, which suggests the need for further tip-up testing and which is often a useful indicator of incipient insulation problems, is also provided.

Despite their small size and low weight, the test sets have comprehensive facilities for assessing the condition of electrical insulation in all types of high voltage equipment, including transformers, bushings, circuit breakers, cables, lightning arrestors and rotating machinery. They can also be used for measuring the excitation current of transformer windings.

To ensure that accurate results are obtained, even when the instrument is powered from a supply with poor voltage and frequency stability, the test sets generate their own test voltage, which is independent of supply quality. A further benefit of this approach is that it allows the test voltage to be varied in frequency from 1 to 500 Hz, making the instruments even more versatile.

DELTA4000 instruments show test results on a large bright built-in colour display. Measured quantities include voltage, current, power loss, tan delta, power factor and capacitance. Test results are automatically stored in the unit and can be downloaded directly to a PC or to a USB memory stick. The results can also be sent directly to a printer via the instrument’s USB port, without the need to use a separate computer.

To further increase their usefulness and convenience, DELTA4000 series instruments are supplied with Megger’s versatile PowerDB Lite software. This allows the operator to run standard automatic tests and to program specific customised test routines in advance.

Two configurations make up the Series: DELTA4110 with external computer (not included) consists of the DELTA4100 control unit and DELTA4010 high-voltage unit; the DELTA4310 comes with onboard computer and consists of DELTA4300 control unit and DELTA4010 high-voltage unit.

For more information contact Stuart Ashton, Surgetek, +27 (0)11 792 1303, info@surgetek.co.za, www.surgetek.co.za

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