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WEG Motor Protection Relays Can Help OEMs to Reduce Their Costs

WEG have launched new electronic motor protection relays to help engineers to improve energy efficiency while reducing stock and design costs.

The WEG RW_E series are highly versatile and efficient electronic motor protection relays to help engineers to reduce their stock management costs, simplify the design process while still ensuring high reliability according to international standards.

They offer a wider adjustment range to suit a broad spectrum of motor powers and deliver 87% less power dissipation than conventional thermal devices, therefore providing enhanced energy efficiency, while ensuring the motor’s smooth running and enabling users to reduce maintenance costs and total cost of ownership.

WEG RW_E Motor Protection Relay Settings

Wide current adjustment range

The RW_E relays’ wide current adjustment range of 1:5 ratio between the lowest and highest settings allows the relays to cover an extensive variety of motor powers at rated operating voltages up to 690 VAC. This enables original equipment manufacturers to reduce their stock of spare parts and associated warehousing costs and invest less time in designing machinery to accommodate different relay models.

“In an increasingly globalised and competitive market it is common that machine manufacturers provide their customers with a choice of motors with different output powers,” says Marek Lukaszczyk, European & Middle East Marketing Manager at WEG. “WEG’s solution means that machine manufacturers can now standardise their control panels, saving time.”

Ratings from 0.4A to 840A

WEG’s new relays have ratings from 0.4A to 840A and protect electric motors for normal or heavy-load starting against overheating due to overload, phase drop-out or phase asymmetry. Powered by the motor’s current without any need for additional external power connections, the RW_E relays feature a special thermal memory which precisely models the heat balance of the motor to ensure optimal protection.

Their low power dissipation can significantly reduce heat load in switch cabinets, enabling the replacement of corresponding equipment in switchgear sets approved to IEC 61439 without new certification.

The relays are just as easy to use as bimetallic motor protection relays and feature manual or automatic reset after tripping. Trip classes 10, 20 & 30 for normal and heavy-load starting can be set easily on the front panel. This makes the RW_E motor protection relays suitable for a wide range of applications and enables users to respond flexibly to changes in existing systems. The relays also include temperature compensation, which ensures consistently high trip accuracy from -20°C to +60°C without any restrictions.

UL certification

The relays provide the highest levels of reliability worldwide and are manufactured and tested to the IEC/EN 60947 international standard (DIN VDE 0660) and UL 60947-4-1A (UL508) certification for the North American market. The RW_E electronic motor protection relays can be combined directly with WEG's CWM and CWB contactors to configure compact and reliable motor starter sets.

“These new relays fit our strategy of end-to-end energy efficiency throughout the drive chain, starting with energy-efficient IE3 to IE5 motors and extending to thermal protection by RW_E electronic relays, short-circuit protection by MPWi circuit breakers, and operational switching by low-loss CWB contactors,” continues Marek.


  • 3-pole solid state overload relays with adjustable trip class: 10, 20 and 30
  • Self-powered
  • Wide adjustment range (5:1)
  • Thermal memory
  • Phase loss protection (less than 5 seconds)
  • Phase unbalance protection (>40% between phases)
  • Temperature compensated (-20°C to +60°C)
  • Manual or automatic reset modes
  • Direct mounting on CWB9...38 and CWM9...105 contactors
  • Separate mounting (with accessories)
  • 1NO + 1NC built in auxiliary contacts

Looking for more information? We can help with that...

WEG Low Voltage Control Gear is feature packed and amazing value for money. Next time you are specifying a new control panel, why not give LC Automation a call to see how much WEG could save you? It can help you to be more competitive, but still retain - or even increase your profit margins. To discuss your requirements and to get an accurate quote for your next project, call LC Automation on 01254 685900 or speak to your local LC Automation Field Sales Engineer.

WEG Low-cost Motor Protection Relays are IE3 Ready



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