The NGRM750 Neutral Grounding Resistor Monitor detects grounding-resistor failures and ground faults and monitors line voltages. It is intended for use in low-resistance grounded (LRG) commercial and industrial power systems. It is an advanced device that allows monitoring of :
Current through the neutral-grounding resistor (NGR)
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
Line-to-line and line-to-ground voltages
A benefit to many users is the multilingual user interface that allows the comfort of reading values and programming in your native language.
It is designed for easy retrofit with a panel mountable human-machine interface (HMI). If preferred, the relay can easily be programmed via the built-in webserver. NGRM750’s can easily connect to a supervisory system with Modbus TCP/IP or RTU communications.
For generator or transformer grounding applications at extreme altitudes, the NGRM750 features a 5,000 m above sea level capability.
It is an ideal solution that is easy to retrofit into existing LRG applications or factory-install in new LRG packages. Capabilities extend to 25 kV and 2,000 A
Features
Determination of RNGR with passive and active measurement methods
Continuous monitoring of the RNGR even if the installation is de-energized
Alarm or trip on ground fault
Monitoring of the current INGR
Monitoring of the voltage UNGR
Faulted-phase indication (optional; up to 690 V direct coupling, otherwise via potential transformers)