Bender Inc. Announces Latest Advancement in Power System Grounding Technology

Bender is proud to announce the latest technology that expands its existing line of Neutral Grounding Resistor Monitors – the NGRM550 and 750. These two protective relays offer industry-leading protection and provide increased safety on low-resistance-grounded transformers and generators. This new advancement in NGR technology follows the NGRM500 and 700, brought to market in 2020 and 2017, respectively. 

The NGRM550 and 750 detect neutral-grounding resistor (NGR) failure and ground faults by measuring the current through the NGR, the voltage between the system neutral and ground, NGR resistance, and its connection between the system neutral and ground. The NGR is monitored whether the power system is energized or offline and with or without the presence of a ground fault.

The device features an integrated web server, Modbus TCP/IP, Modbus RTU, and an HMI (Human-Machine Interface) for local metering and easy programming.

Benefits of the NGRM550 and 750 include:

  • Improved safety with monitoring of the grounding connection 
  • Voltage between the transformer or generator neutral point and ground (voltage drop across the NGR)
  • NGR failure (open), including failure of connections between neutral and ground
  • Ability to use standard iron core CT’s (current transformers) to allow range of ground-fault settings that matches higher current faults
  • AC/DC ground-fault protection/detection to properly monitor non-linear loads, such as adjustable speed drives
  • Preventative maintenance as a result of sensitive ground-current detection levels

Production units of the NGRM550 and 750 are now available. Don't hesitate to contact your local Bender representative or fill out our contact form for more information.


Bender Inc., located in Exton, PA, is a subsidiary of Bender Group, a family-owned company and global leader in providing electrical products and solutions to a variety of industries and applications. The Bender Group has headquarters in Grünberg, Germany, with operations in 11 countries worldwide and representatives in an additional 70 countries.