The ngr system is designed for use with littelfuse neutral grounding resistor monitors for complete system grounding and grounding protection. The installation voltage and code being used nec nesc will determine how the nrg is applied along with how the system is treated under the nec a 600 volt and under system does not permit l n loads.
Restricted Earth Fault Protection 64r Working Transformer
Ngr connection diagram. Dual ethernet ports are available with support for fiber optic and rj45 interfaces. Inside the ngr and must be installed on site 46 tools and equipment ordinary hand tools are all that are needed for assembly. Neutral through a resistance which limits. Lifting equipment must be capable of keeping the unit in an upright position while in motion. Side of the ngr is connected directly to a suitable ground. Ngrneutral grounding resistor is nothing but a high resistance grounding which in context of electrical power system means the grounding of the system.
Awg stranded copper wire resistance size diameter resistance at 77ºf awg inch mm ohm1000 ohmkm 18 00465 1182 65227 21400 14 00740 1880 25756 8450. The ngr series us systems are designed for use in us applications and all other parts of the world not including canada. 13 ngr short detection firmware version 300 and higher the se 330 can be configured to monitor and trip if the ngr. 2 the ngr fault auxiliary trip relay can be used to give door mounted or remote indication of a ngr failure. For ease of connection to new devices the rs 232 interface has been replaced by a mini b usb port. Assuming the ngr is rated for the direct secondary voltage its inserted between the xo terminal and the groundingearthing system.
The ngr also provides a convenient point for monitoring the ground fault current. In some cases the resistor may actually be wired to the secondary of a single phase transformer which has its primary wired in series with the power systems neutral to ground connection. In the event that a ground fault condition exists the ngr typically limits the current to 200 400a though most resistor manufacturers label any resistor that limits the current to 25a or greater as low resistance. The ngr mr has an isolated ct input so that one side of the external ct secondary may be grounded. For applications in canada please use the ngr series canada. An added iec61850 protocol.
3 the ground fault auxiliary trip relay can be used to give door mounted or remote indication of a ground fault trip. A battery powered drill can be handy for removing cover screws but is not required. Neutral grounding resistors ngrs limit the fault current when one phase of the system shorts or arcs to ground. No special tools are required.
Gallery of Ngr Connection Diagram
