3RR2142-1AW30 Siemens SIRIUS Current monitoring relay


  • 3RR2142-1AW30
  • Monitoring relay
  • Mountable on 3RT2 contactor
  • Size S0
  • Analogue adjustable
  • Apparent current monitoring 4-40.0 A
  • 50-60 Hz
  • 2-phase
  • 24-240 V AC/DC
  • 1 x changeover contact
  • Screw connection

Out of stock

Current monitoring relay Siemens SIRIUS 3RR2142-1AW30


SIRIUS 3RR2242, 3RR2142, 3RR2243 current monitoring relays

The SIRIUS 3RR2 current monitoring relays are suitable for load monitoring of motors or other loads. In two or three phases they monitor the rms value of AC currents for overshooting or undershooting of set threshold values.

Whereas apparent current monitoring is used above all in connection with the rated torque or in case of overload, the active current monitoring option can be used to observe and evaluate the load factor over a motor’s entire torque range.

The 3RR2 current monitoring relays can be integrated directly in the feeder by mounting on the 3RT2 contactor; separate wiring of the main circuit is therefore superfluous. No separate transformers are required.

For a line-oriented configuration or simultaneous use of an overload relay, terminal supports for stand-alone installation are available for separate standard rail mounting.


Basic versions

The basic versions with 2-phase apparent current monitoring, a CO contact output and analog adjustability provide a high level of monitoring reliability especially in the rated and overload range.

Standard versions

The standard versions monitor the current in three phases with selectable active current monitoring. They have additional diagnostics options such as residual-current monitoring and phase sequence monitoring, and they are also suitable for monitoring motors below the rated torque. These devices have an additional independent semiconductor output, an actual value indicator, and are digitally adjustable.

Both versions are available optionally with screw terminals or spring-loaded terminals, in each case for sizes S00 and S0. With variants of size S2 the main conducting paths always have screw terminals; the control current side can have screw or spring-loaded terminals.


In addition to the features of the standard versions, the 3RR24 monitoring relays for mounting on 3RT2 contactors for IO-Link also offer the possibility of transmitting the measured values and diagnostics data to a controller via an IO-Link. Furthermore, the devices can be parameterized on the devices themselves or via IO-Link.

For more information, see .

3RR21 and 3RR22 overview table

✓ Available

— Not available

Possible combinations of 3RR21/3RR22 monitoring relays with 3RT2 contactors

✓ Available

Article No. scheme


The Article No. scheme shows an overview of product versions for better understanding of the logic behind the article numbers. For your orders, please use the article numbers quoted in the selection and ordering data.


  • Directly mountable onto 3RT2 contactors and 3RA23 reversing contactor assemblies, i.e. no additional wiring outlay in the main circuit
  • Optimally coordinated with the technical characteristics of the 3RT2 contactors
  • No separate current transformer required
  • Versions with wide voltage supply range
  • Variably adjustable to overshoot, undershoot or range monitoring
  • Freely configurable delay times and RESET response
  • Display of ACTUAL value and status messages
  • All versions with removable control current terminals
  • All versions with screw terminals or spring-loaded terminals
  • Simple determination of the threshold values through direct reference to actually measured values for setpoint loading
  • Range monitoring and selectable active current measurement mean that only one device for monitoring a motor is required along the entire torque curve.
  • In addition to current monitoring it is also possible to monitor for broken cables, phase failure, phase sequence, residual current and motor blocking.


  • Monitoring of current overshoot and undershoot
  • Monitoring of broken conductors
  • Monitoring of no-load operation and load shedding, e.g. in the event of a torn V-belt or no-load operation of a pump
  • Monitoring of overload, e.g. on conveyor belts or cranes due to a high load
  • Monitoring of functionality of electrical loads such as heaters
  • Monitoring of incorrect phase sequences on mobile equipment such as compressors or cranes
  • Monitoring of high-impedance faults to ground, e. g. caused by damaged insulation or moisture

Technical specifications

Function diagrams of 3RR214.-.A.30 basic variants, analogically adjustable

Closed-circuit principle upon application of the control supply voltage

Current overshoot

Current undershoot

Range monitoring

Function diagrams of 3RR224.-.F.30 standard versions, digitally adjustable

With the closed-circuit principle selected upon application of the control supply voltage

Current overshoot

Current undershoot with residual-current monitoring

Range monitoring

Phase sequence monitoring


Monitoring relay, can be mounted to Contactor 3RT2, Size S0 basic, analog adjustment Apparent current monitoring 4…40 A, 50…60 Hz, 2-phase Supply 24-240 V AC/DC 1 change-over contact Monitoring for Current overshoot and undershoot Phase failure, Cable break with or without fault buffer ON delay 0-60 s Noise pulse suppression 0-30 s Switching hysteresis 6% Screw connection system


DataSheet in PDF

Weight 0.260 kg
Dimensions 99.00 × 115.00 × 57.00 mm


product brand name


product designation

Monitoring relays

design of the product

analogically adjustable, 2-phase current monitoring

product type designation


size of contactor can be combined company-specific


operating apparent power rated value

4 V·A

insulation voltage for overvoltage category III according to IEC 60664

● with degree of pollution 3 rated value

690 V

surge voltage resistance rated value

6 kV

protection class IP

● on the front


● of the terminal


shock resistance

15g / 11 ms

vibration resistance

10 … 55 Hz / 0.35 mm

mechanical service life (switching cycles) typical

10 000 000

electrical endurance (switching cycles) at AC-15 at 230 V typical

100 000

reference code acc. to IEC 81346-2


relative repeat accuracy

2 %

type of voltage of the supply voltage


supply voltage 1 at AC

● at 50 Hz

24 … 240 V

● at 60 Hz

24 … 240 V

supply voltage 1 at DC

24 … 240 V

supply voltage frequency 1

50 … 60 Hz

type of current for monitoring


adjustable current response value current

● 1

4 … 40 A

● 2

4 … 40 A

adjustable response delay time

● when starting

0 … 60 s

● with lower or upper limit violation

0 … 30 s

temperature drift per °C

0.1 %/°C

number of CO contacts

operational current of auxiliary contacts at AC-15

● at 230 V

3 A

● at 400 V

3 A

operational current of auxiliary contacts at DC-13

● at 24 V

1 A

● at 125 V

0.2 A

● at 250 V

0.1 A

contact rating of auxiliary contacts according to UL

B300 / R300

operating power rated value

2.5 W

ampacity of the semiconductor output in SIO mode

200 mA

operational current at 17 V minimum

5 mA

EMC emitted interference acc. to IEC 60947-1

ambience A (industrial sector)

EMC immunity acc. to IEC 60947-1

ambience A (industrial sector)

product component removable terminal for main circuit


product component removable terminal for auxiliary and control circuit


type of electrical connection

● for main current circuit

screw-type terminals

● for auxiliary and control circuit

screw-type terminals

● for main contacts

● at AWG cables for main contacts

2 x (16 … 14), 2x (14 … 8)

connectable conductor cross-section for main contacts

● solid or stranded

1 … 10 mm²

● finely stranded with core end processing

2.5 … 10 mm²

type of connectable conductor cross-sections

● for auxiliary contacts

— solid

1x (0.5 … 4 mm²), 2x (0.5 … 2.5 mm²)

— finely stranded with core end processing

1x (0.5 … 2.5 mm²), 2x (0.5 … 1.5 mm²)

● at AWG cables for auxiliary contacts

2x (20 … 14)

AWG number as coded connectable conductor cross section for main contacts

16 … 8

tightening torque with screw-type terminals

0.8 … 1.2 N·m

mounting position


fastening method

direct mounting

required spacing

● with side-by-side mounting

● for grounded parts

● for live parts

— forwards

6 mm

— backwards

0 mm

— upwards

6 mm

— downwards

6 mm

— at the side

6 mm

installation altitude at height above sea level maximum

2 000 m

ambient temperature

● during operation

-25 … +60 °C

● during storage

-40 … +80 °C

Test Certificates

Marine / Shipping

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