Austrian innovator turns to Rockwell for heat-pump project

Matrei, Austria - IDM-Energiesysteme GmbH (IDM), based in Matrei, is a Euro17-millon turnover company specialising in technologies that use energy from the earth and sun. Its innovations include a heating system that combines a solid-fuel boiler for winter; a heat pump for spring and autumn; and solar cells for summer and an hygienic water heating that kills bacteria linked to Legionnaire’s disease.

“In the history of our company, there’s been many a time when our competitors shook their heads and said: ‘Here’s another weird invention that nobody needs.’" said Paul Hysek, IDM marketing director. “But five or ten years later they shook their heads again and wondered: ‘Why didn’t we think of that?’”

A current focus for IDM is heat pumps, in particular the power issues that can happen when a pump switches itself on. A weak power supply can be drained, so energy utilities require the installation of a starting current limitation system in motors with upwards of 3 kW of power to prevent 'current hogging'.

This requirement led IDM to Rockwell Automation a few years ago. “We were looking for an electronic part that could smooth electricity spikes when the machine was switched on and keep them as low as possible,” said Mario Mayr, who heads up electrical engineering at IDM.

The Allen-Bradley SMC-3 had two things going for it: first, one of IDM’s Machine Builder partners had always been happy with Rockwell products; and second, this soft starter was a perfect fit with IDM’s machine design.

“Our Allen-Bradley SMC-3 is a three-phase controlled device with a compact footprint that comes with multiple useful functions as standard. These include complete motor protection, integral bypass, and rotating field control. IDM works with scroll compressors, and if these rotate for a while in the wrong direction, they break,” said Peter Lehner, account manager at Rockwell.

IDM’s previous technology was based on the interaction of several components such as contactors, circuit breakers, motor protection relays and various others. During a period of two years, IDM completed the change from this traditional circuit design over to the new technology where a Soft Starter was practically the only component in the control box.

“With about 150 system solutions, we have a very wide variety of machines ranging from 3.5 to 300 kW, so changing the wiring diagrams was quite a bit of work on its own. But we thought about this very carefully and weighed up all the pros and cons to make sure the changes would really pay for themselves,” notes Mario Mayr.

The changeover to the Rockwell technology enabled a reduction in stock inventory. Electronic motor protection relays with a 7 to 35A wide adjustment range offering more flexibility than the bi-metal relays that only range from 7 to 10 amps. As a result, the space needed in the control box was reduced to about a fifth of the previous requirement and the failure frequency of the heat pumps was reduced too.

“In the home environment you often get mains fluctuations. If the bimetal relay reacts to that, you need to call a service engineer,” said Mayr. “With the electronic motor protection relay, all you need to do is press the on-off button to reset it.”

“We found Rockwell Automation convincing in terms of both quality and delivery capacity, and I’m very happy with the technical consulting side of things too,” says IDM’s Mayr. “As an engineer I don’t have time to spend plowing through brochures and assembly instructions. Someone comes here, advises me, and together we find the right product for our needs.”