ISOTEST® Phantom Grounding for high-voltage testing

HEILIGENHAUS, Germany - May 8, 2015 - PRLog -- For the corrosion protection of pipeline pipes a protective coating is applied on their surface. Within the frame of quality assurance these pipe coatings are tested for cracks or defects by means of high-voltage in order to guarantee the durability and longevity of the pipes. Proper grounding of the high-voltage testing instrument is an absolutely essential precondition for all high-voltage tests. By grounding i.e. the connection of the testing device with the non-isolated pipe end as well as the connection of the pipe to the ground potential, the power circuit is closed. In case a conductive connection to the bare pipe end is not possible, ELMED Messtechnik offers the possibility of capacitve grounding – also known as “phantom grounding”. For this grounding method the ISOTEST® grounding collar is used. This grounding collar is made of special conductive rubber and available for pipe diameters from DN100 to DN 1400. Within the frame of high voltage testing of insulating coatings this grounding method is only possible when working with test devices using pulse voltage. Wrapped around the pipe to be tested in the fitting size and tightened, one side of the collar is connected to the soil (grounding cable with grounding rod) and the other side is connected to the testing device.

Advantages

In contrast to other grounding methods the grounding collar offers the possibility – even without direct contact to the non-isolated pipe end – to ensure a safe grounding. This very flexible grounding method is exclusively possible with pulse voltage (as applied with the ISOTEST®) or AC voltages. It is of utmost importance to keep in mind that grounding collars cannot be used in combination with DC-voltage units!

Functioning

How does this capacitive grounding method function? – A short excursion into the electronic technology. Two conductive surfaces (for example the pipe and the grounding collar made of conductive rubber) that are separated by an insulating layer (corrosion protection coating), may get electrically in contact when applying impulse voltage. In this way voltage compensation is possible between the steel pipe and the grounded grounding collar. In the event of a flashover caused by a holiday or a crack the transferred electrical voltage is discharged by means of the grounding collar. Hence the grounding collar ensures a safe and reliable test!

For further information on the capacitive grounding please visit our website at www.isotest.de

Elmed Dr. Ing. Mense GmbH

Weilenburgstr. 39

42579 Heiligenhaus

Tel.: +49 2056 9329-0

Fax: +49 2056 9329-33

www.isotest.de

ELMED specialises in the design and manufacture of measuring and testing equipment. For over 65 years customers in many technical fields have been relying on this middle-sized company.

Over the years ELMED has contributed to the progress made in many technical branches. These contributions are based on product innovation and product quality. ELMED provides decades of experience in manufacturing equipment for measuring and testing, technically refined, customised solutions and innovation based on strong research and development. The qualified and experienced technical experts deliver products and services of the highest standard. The European network of representatives and OEMs guarantee Europe-wide customer proximity. Well-proven standard products, modern technology, individual systems and complete solutions: The business sectors of high voltage technology, stroboscopy and metal detection provide tailored solutions for specific requirements. Planning, conception and execution under one roof guarantee optimum product performance, on-time delivery and cost minimization.