User Manual

3RR2 current monitoring relays
4.2 Application areas
3UG4 / 3RR2 monitoring relays
42 Manual, 02/2013, NEB927043002000/RS-AA/002
4.2 Application areas
The 3RR2 current monitoring relays are used, for example, in the following applications:
● Monitoring for current overshoot and current undershoot
● Monitoring for cable breaks
● Monitoring for no-load operation and load shedding (as might be the case, for example, in
the event of a torn V belt)
● Underload monitoring in the lower performance range (if a pump was running in no-load
operation, for example)
● Monitoring for overload (as might affect pumps with a soiled filter system, for example)
● Monitoring the performance of electrical loads such as heaters
● Monitoring for incorrect phase sequences on mobile equipment such as compressors or
cranes
● Monitoring for high-impedance faults to ground (caused by damaged insulation or
moisture, for example)
Table 4- 1 Application areas of the 3RR2 current monitoring relays
Function Application
• Undercurrent
• Overcurrent
• Apparent current
• Active current (3RR22 only)
• Phase failure / wire break
• Phase sequence (3RR22 only)
• Internal ground fault detection (fault
current) (3RR22 only)
• Block current (3RR22 only)
• Emergency lighting
• Heating systems (electroplating plants, plastic
injection machines, paintshops)
• Lamps (tunnels, OR lighting, traffic lights, signal
systems, UV lamps, infrared radiators, laser lamps)
• Fan
• Pumps
• Sawing system
• Conveyor belt
• Surface grinding machine
• Breaking mill
• Milling machine
• Car wash
• Lifting platform
• Screw conveyor
• Crane
• Turning machine
• Woodworking
• Grain mills
• Steel industry