Siemens SIRIUS 3RH Series, System Manual

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SIRIUS 3RR2 current monitoring relays
8.10 Technical data
SIRIUS Innovations
734
System Manual, 01/2011, A8E56203870002-03
8.10.1.2 Monitoring functions
Table 8- 15 Monitoring functions of 3RR2 current monitoring relays
Feature Benefit 3RR21 Basic,
analog setting
3RR22 Standard,
digital setting
Current overshoot 
Provides optimum current-dependent
protection of loads against impermissibly high
temperature rise due to overload
 Enables detection of filter blockages or pumps
working against closed slide valves
 Enables conclusions to be drawn about wear,
poor lubrication or other phenomena relevant
to maintenance
✓ (2-phase) ✓ (3-phase)
Current undershoot 
Enables detection of overload due to a slipping
or torn belt

Ensures that pumps are protected against
running dry

Straightforward function monitoring of resistive
loads such as heaters

Permits energy savings to be made through
monitoring of no-load operation
✓ (2-phase) ✓ (3-phase)
Apparent current monitoring 
Sensitive current monitoring specifically in a
motor's rated and upper torque range
✓ ✓
Active current monitoring 
Optimum current monitoring over a motor's
entire torque range thanks to the patented
combination of power factor and apparent
current monitoring
- ✓ (selectable)
Range monitoring 
Simultaneous monitoring for current overshoot
and undershoot with a single device
✓ (2-phase) ✓ (3-phase)
Phase failure, wire break 
Minimizes the temperature rise of the three-
phase motor in the event of a phase failure
thanks to immediate disconnection

Prevents hoisting gear from operating with half
payload
✓ (2-phase) ✓ (3-phase)
Phase sequence error 
Prevents motors, pumps or compressors
starting up in the wrong direction of rotation
- ✓ (selectable)
Internal ground-fault
detection (fault current
monitoring)
 Provides optimum protection of loads in the
event of high-impedance faults to ground
caused by moisture, condensation, damaged
insulation, etc.

Eliminates the need for additional special
equipemnt

Saves space in the control cabinet

Reduces wiring outlay and costs
- ✓ (selectable)
Blocking current monitoring
 Prevents temperature rise of the three-phase
motor in the event of blocking during operation
thanks to direct disconnection

Minimizes the mechanical loading of the
system by functioning as an electronic shear
pin
- ✓ (selectable)