Functions; Functions And Parameters - Siemens SIRIUS 3RT Series System Manual

SIRIUS 3RR2 current monitoring relays

8.4 Functions

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/Parameters
Lower threshold value
(I▼/I!▼)
Upper threshold value
(I▲/I!▲)
ON-delay time (onDel)
Tripping delay time
(Del)
Reclosing time (RsDel)
Relay switching
behavior (NO / NC)
Reset behavior
(Mem)
Hysteresis threshold
value (Hyst)
690
Functions and parameters of the 3RR2 current monitoring relays
Basic current monitoring relay
3RR2141-.A.30
OFF/1.6 to 16 A OFF/4 to 40 A
1.6 to 16 A/OFF 4 to 40 A/OFF
0 to 60 s
0 to 30 s
-
Closed-circuit
principle
Automatic/manu
al
6.25% x
threshold value
Standard current monitoring relay
3RR2142-.A.30 3RR2241-.F.30
OFF/1.6 to 16 A
1.6 to 16 A/OFF
0 to 60 s 0 to 99 s
0 to 30 s 0 to 30 s
- 0 to 300 min
Closed-circuit Closed-circuit
principle principle/open-
circuit principle
Automatic/manual Automatic/manu
al
6.25% x 0.1 to 3.0 A
threshold value
System Manual, 01/2011, A8E56203870002-03
3RR2242-.F.30
OFF/4 to 40 A
4 to 40 A/OFF
0 to 99 s
0 to 30 s
0 to 300 min
Closed-circuit
principle/open-
circuit principle
Automatic/manu
al
0.1 to 8.0 A
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