Case Studies

Busy Sheffield engineers keep on top of testing with Whitelegg

Established in 2007 with a heritage spanning over 100 years and which included BTH, AEI, GEC and Alstom, Quartzelec has grown to be a major force in UK and overseas electrical and mechanical engineering. Their many workshops cover the country with their Sheffield site specialising in servicing, testing and repair of AC and DC rotating machines ranging from fractional HP motors up to 600MW Generators.

The organisation serves a number of major industries including power generation, heavy engineering, MOD, utilities, petrochem, pharma and processing.

These major clients demand a responsive and high quality service from all departments and in the area of motor testing Quartzelec are relying on the *Baker test instrument the AWA-IV-12kv supplied by Whitelegg Machines of Crawley.

Condition Monitoring

The verification of a motor's winding condition, before, during and after repair is a critical factor in the firms ISO 9001:2008 accreditation. The standard test methods of winding resistance, meg-ohm, PI and hipot are part and parcel of the programme. But Matt Brown, Ops Manager for Sheffield and Grimsby branches was looking for an instrument that combined these tests, and others, as well as most importantly providing a repeatable record of the motor's servicing history for condition monitoring, as is now expected by customers.

Matt Brown became aware of the Baker AWA some 6 years ago through meetings with Mike Herring at Whitelegg and conversations with industry colleagues. The first machine was purchased with others following at Swansea and Grimsby with other branches to follow suit.

The AWA delivers all major electrical tests in a compact, field-portable unit and is the only high voltage tester that can be pre-programmed in the office ready for field testing. The instrument incorporates the most advanced surge testing capabilities yet seen in portable equipment, with computer control superseding the earlier manually controlled instruments. The surge test is the only method of detecting turn to turn (copper to copper) insulation weakness.

The AWA begins surge generation at low DC voltages with comparisons being made with previous wave forms to detect any sign of turn to turn shorting. Shorts among windings in parallel can also be located, something that was never possible before by visually comparing waveforms. With the AWA, fewer pulses are applied so reducing the power required to perform the test.

If no turn-to-turn shorting is detected the final pulse wave is stored as the reference wave form for all future tests and acts as a permanent record of each motor's characteristics

In a recent project at Grimsby the test was performed on a 415V motor which was identified to have a breakdown in the turn-to-turn winding insulation. This presented the opportunity to inform the end user of the potential insulation failure to earth prior to the actual failure occurring. As recommended the Customer opted for a rewind of the stator, therefore eliminating the highly likely event of an unscheduled / costly down period.

The acquisition of the AWA has helped Matt to win several major contracts; one being the servicing and repair of the 6.6 Kv stand-by generators and 3.3Kv pumps on a North Sea oil rig. Furthermore a substantial contract has just been won at the MOD. Here Quartzelec beat off stiff local competition with their bid which included surge testing with the AWA 12.

Matt Brown is now an enthusiastic champion of the AWA's technology and enthusiastically comments "The AWA adds enormously to our comprehensive portfolio of test equipment giving added value to our end users and helping us maintain our lead in this competitive environment"