Worldwide, there are only a handful of manufacturers of electrical actuators for the process industry, and the Vienna, Austria-based company Schiebel Antriebstechnik GmbH is the smallest of these. The company's technology is tucked away in the interior of the actuators, ensuring that flows can be regulated in an accurately controlled manner, even in difficult applications. The VLT® Midi Drive FC 280 AC drive from Danfoss Drives is used to ensure actuator quality at Schiebel.

Schiebel actuators provide precision control for a wide range of industries, even in extreme climates and harsh environments.

Schiebel is the only Austrian producer of electric actuators. These actuators are used anywhere that the supply and removal of solid, liquid, or gaseous substances needs to be controlled. According to company director Klaus Schiebel, “At our factory in Vienna, we produce around 7,000 actuators each year with 56 employees, and we have the entire production chain in our own hands, from development to construction, mechanical finishing, and assembly and packaging.”

This is due to the fact that the Schiebel actuators are considerably more compact than competitive products with the same performance. When it comes to markets, the Viennese company delivers worldwide, but with a leaning towards Eastern and Southeast Europe, partly due to history and partly due to market conditions. Schiebel places value on proximity to the customer, and is represented internationally not only by dealers, but also by its own subsidiaries.

A Technological Specialty

Schiebel builds on a technological specialty: their “failsafe” actuators. “Electric actuators have a weak point — if the power supply fails, then the actuator fails, which can lead to problems in certain areas of the oil and gas industry,” explained Stephan Vasiljevic, who is responsible for electrical engineering at Schiebel.

About 20 years ago, technicians from Schiebel had to deal with this weakness using a spring reset mechanism. Today, the technology that evolved from this is highly in demand on the market. “Our failsafe function is a major factor in our strategy of winning customers with technology,” said Schiebel. But Schiebel also has taken into account the trend towards decentralization in process automation with the development of its own control system for actuators.

“With Smartcon controls, the intelligence is moving out into the field,” explained Vasiljevic. “The integration to the control system uses widespread field-bus technologies.” In addition, the control system enables comprehensive diagnostics.

Precision Control

The Danfoss VLT Midi Drive FC 280 fits into the Schiebel actuators, and eliminates the need for an oversized converter.

While most actuators only have a relatively simple “open-closed” functionality, a number of applications are significantly more demanding. These require a high degree of accuracy, and the flow control must be able to be carried out in precise, small steps. “Applications for this type of actuator can be found, for example, in gas pipelines or steam conditioning,” said Vasiljevic. This fine process control is realized by means of an AC drive, and this is where Danfoss comes in.

The AC drives have to meet a range of requirements. One point is the frame, since the AC drive is not placed in a switch cabinet, but is integrated directly into the actuator control. This in turn means that the heat dissipation must occur without additional cooling. Very few other AC drives on the market have the required compact and robust design.

“One of our most important requirements is that the highest torque is available on startup,” said Vasiljevic. Previously, this requirement usually meant using an oversized converter. With Danfoss’ VLT® Midi Drive FC 280, this is now no longer necessary, which has a positive impact, not least of which is on the costs. Control and parameterization of the AC drive is performed using Schiebel's Smartcon control. Danfoss has launched an AC drive that represents the state of the art across all its characteristics. “The support of a wide range of fieldbus systems, the control of permanent magnet motors, an integrated STO (Safe Torque Off) function, the USB interface, and last, but not least, the new memory module are just some of the features that make the FC 280 a consistent package for OEMs,” according to Gunter Schwarz, Global Product Marketing Manager at Danfoss in Guntramsdorf.

A Complete Solution

Another important factor is having excellent support, both very close by and globally. Klaus Schiebel is satisfied with the FC 280 drive on all counts. “It is technologically state-of-the-art, offers high performance with correspondingly short response times, easily fits into our enclosures thanks to its compactness, and offers very good value for the money.”

It is no surprise, then, that Danfoss AC drives are also part of the largest individual order in Schiebel's history. Schiebel sales and service manager Michael Piller said, “We are delivering around 1,000 actuators for the construction of a 660 MW lignite power plant in Greece (Ptolemais V), about 300 of which are controlled by AC drives.”

This article was contributed by Danfoss Drives, Baltimore, MD. For more information, Click Here.