
![]() |
Charlotte Stonestreet
Managing Editor |
No reluctance to save energy
26 April 2016
Up to 15% lower energy use, a significant reduction in motor maintenance costs and a drop in audible noise are being achieved with the installation of a synchronous reluctance motor and drive package on a twin extruder
Radius Systems’ plant in Derbyshire houses 14 extrusion lines, each of which produces polyethylene pipes from 16 to 1200mm, together with an injection moulding facility, which makes the associated fittings for utility companies for gas and water transfer.
Eight lines have been powered by DC motors, many of which are over 20 years old. However, Line 12 had a high utilisation rate and yet the 182kW DC motor was regularly failing, leading to an increase in downtime and rising maintenance costs. Radius estimates that the annual static and dynamic checks, brush changes and outsourced labour costs alone are about £2000 per motor.
ABB’s local systems integrator, Inverter Drive Systems (IDS), carried out before and after monitoring of the DC motor on Line 12, in order to determine the energy savings, while confirming that an investment in an AC motor and drive would meet Radius Systems’ three year capital payback policy.
“Monitoring of the application is critical to the success of any installation,” explains Phil Nightingale, Sales Engineer, IDS. “It allows us to accurately determine the real energy saving potential, which means we can size the AC motor and drive correctly. We are often able to reduce the size of the motor and drive package required while exceeding the production targets.”
It was through monitoring that IDS was able to determine the speed range of the line’s DC motor, which revealed that it was over-sized for the application and hence consuming more energy than necessary. Also, despite the motor having been regularly maintained, it was 20 years old and nowhere near operating at its original efficiency.
Higher efficiency
The SynRM is a 200kW, 1500rpm, IE4 motor. Together with the ABB industrial drive, ACS880, it offers a much higher efficiency than standard AC induction motors and drives. It was estimated that potential energy savings from a synchronous reluctance motor and drive (SynRM) package for Line 12 would be in the range from 8 to 15%, with a return on investment within two years. In addition, in excess of £2,000 cost avoidance is estimated with the removal of DC motor maintenance.
“IE4 and higher efficiencies are the way forward, so provided the price is competitive, the return on investment can be justified,” explains Rob Betts, Engineering Manager at Radius Systems. “To pick an exact production run that can give an accurate energy measurement is very difficult to quantify, hence the range from 8 to 15%. The actual energy saving is dependent upon several process variables, such as raw material type, different product ranges and profiles, the temperature at the die and the barrel and the general ambient environmental conditions. For instance, energy consumption is higher on a cold day, as more energy is needed to warm up the process."
The SynRM is also a far quieter package than the existing DC motor. “SynRM has given us a reduction in noise in the production hall which is a benefit we had not expected,” says Betts. “While we have not measured the noise levels, everyone has noticed a definite reduction across the plant.”
A challenge was presented by the physical footprint of the existing DC motor. “DC motors tend to be long and thin,” explains Betts, “whereas AC motors tend to be shorter but bigger in diameter.” However, SynRM can be up to two frame sizes smaller than a conventional induction motor.
While SynRM is well tested on quadratic torque applications, like pumps, fans and compressors, there are fewer installations, such as extruders, which require constant torque. Despite this Betts was confident: ““We have some 300 motors on site, of which about a fifth are variable-speed. At no time did we feel that we were taking a risk with this new technology, as it had been widely tested. We were able to meticulously plan the changeover of the DC drives to SynRM so that the entire installation and commissioning was carried out in just five days.”
Key Points
- A 182kW DC motor used on a line at Radius Systems was regularly failing, leading to an increase in downtime and rising maintenance costs
- Inverter Drive Systems (IDS) ascertained the DC motor was over-sized for the application and consuming more energy than necessary
- The SynRM now used together with the ABB industrial drive, ACS880, offers much higher efficiency than standard AC induction motors and drives.
- IE5 efficiency without rare earth magnets
- Savings Galvanised
- ABB’s robot training masterclasses now available online
- SynRM motor & VSD packages
- Robots for machine tending
- Plan to increase production output & cut energy bills
- It’s never too late to save energy using variable speed drives
- Reversing rougher powered
- ABB tech monitors orphan wells
- Higher throughput, lower energy use
- No related articles listed