SIRIUS 3RR2 current monitoring relays
8.4 Functions
SIRIUS Innovations
690 System Manual, 01/2011, A8E56203870002-03
8.4 Functions
8.4.1 Functions and parameters
Function
The 3RR2 current monitoring relay is supplied with a 24 V DC/AC or 24 to 240 V DC
auxiliary voltage and monitors the current for overshoots, undershoots or both (range
monitoring) in accordance with the parameters set. In the event of a fault, it trips at the end
of the set delay times.
System protection by means of true rms measurement (tRMS)
SIRIUS 3RR2 current monitoring relays are used for load monitoring of motors or other
loads. They are also capable of two- or three-phase monitoring of the true rms value (tRMS)
of AC currents for overshooting and/or undershooting set threshold values.
The 3RR2 current monitoring relay works with an electronic measuring method which
calculates the actual (effective) value of an alternating current, regardless of whether the
current's waveform is purely sinusoidal or distorted.
The current monitoring relay responds immediately even to minor changes in the current
value. It provides a means of ensuring that the processes in the machine are monitored
continuously and protects the system against damage.
Functions and parameters of the 3RR2 current monitoring relays
Table 8- 2 Functions and parameters of the 3RR2 current monitoring relays
Basic current monitoring relay Standard current monitoring relay
Functions/Parameters
3RR2141-.A.30 3RR2142-.A.30 3RR2241-.F.30 3RR2242-.F.30
Lower threshold value
(Iâ–¼/I!â–¼)
OFF/1.6 to 16 A OFF/4 to 40 A OFF/1.6 to 16 A OFF/4 to 40 A
Upper threshold value
(Iâ–²/I!â–²)
1.6 to 16 A/OFF 4 to 40 A/OFF 1.6 to 16 A/OFF 4 to 40 A/OFF
ON-delay time (onDel) 0 to 60 s 0 to 60 s 0 to 99 s 0 to 99 s
Tripping delay time
(Del)
0 to 30 s 0 to 30 s 0 to 30 s 0 to 30 s
Reclosing time (RsDel) - - 0 to 300 min 0 to 300 min
Relay switching
behavior (NO / NC)
Closed-circuit
principle
Closed-circuit
principle
Closed-circuit
principle/open-
circuit principle
Closed-circuit
principle/open-
circuit principle
Reset behavior
(Mem)
Automatic/manu
al
Automatic/manual Automatic/manu
al
Automatic/manu
al
Hysteresis threshold
value (Hyst)
6.25% x
threshold value
6.25% x
threshold value
0.1 to 3.0 A 0.1 to 8.0 A
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