Drives and Controls Magazine

ABB lashes out at poor quality motors

01 April, 2002

ABB lashes out at poor quality motors

Steve Ruddell, senior vice-president of ABB`s motors business in the UK, is warning that poor-quality motors are costing British industry millions of pounds annually in plant downtime, wasted energy and the cost of replacing failed motors. He asserts that the erosion of UK motor prices in recent years is about to backfire in widespread premature motor failures.

"UK industry is wasting vast sums of money by buying low-cost motors that can`t offer durability," he says. "In the past 12 months, ABB and its distributors have received many calls to replace motors from other manufacturers that have clearly failed through the use of inferior materials and low-cost production methods," Ruddell reports.

"We have seen motors running excessively hot, we have seen cracked castings, burnt-out windings, sub-standard insulation systems and much more."

Ruddell argues that many of the failures are a result of poor construction and the use of cheap materials. "About 55% of the cost of a motor goes towards materials alone," he points out. "This means that if you want to cut costs significantly, there is very little else, apart from the quality of materials to cut into."

For example, the winding shown above failed because of poor mechanical rigidity. At start-up, the current can be more than seven times the motor`s rated nominal current.The energy in the windings creates a pulsating force and if the insulation fails to keep the windings in place, hotspots can occur, causing the insulation between the phases, or between a phase and earth, to break down, resulting in a short-circuit and motor failure.

Ruddell concedes that for applications that only need a motor to run a pump for two hours once a month, it makes sense to sacrifice durability for price. But for continuous processes, where downtime costs can run into thousands of pounds an hour, motor specifiers need to be more careful.

He points out that unplanned stoppages can cost as much as a new motor every five minutes. "While a high-durability motor often gives you more than 10-15 years of trouble-free service, depending on the frame size, the cheaper alternative may only give you two to three years."

Some of the prices of the new motors are remarkable. Ruddell cites the example of a Chinese-made 316kW, four-pole machine with a European-sounding name which has recently gone on sale in the UK for £2,950. The list price of the equivalent ABB motor is £13,400.

One problem that motor choosers face is that competing machines look similar from the outside because they conform to IEC standards. "You can`t tell a motor`s longevity by looking at the outside of the package," Ruddell warns.

To help motor users to make an informed choice, ABB has published a Motor Quality Guide, outlining the factors that it contends make a high-quality motor. It is also opening a discussion forum on its distributors` Web site where users can share their motor experiences .