Electronic Current-Transducer Type STWA4MH

AC Electronic current transformer, AC 0 - 60 A, with interface RS485

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Part number


Product description


STWA4MH is a measuring transducer. It measures AC up to 60A and has an RS485 interface (Modbus RTU). The measured analog current value is made available as a digital signal and can be read by a PLC, an IPC or a master computer.

The conductor to be measured is passed through an opening (Ø 11 mm). In case of small currents, the sensitivity of the current transducer can be increased by looping through the current-carrying conductor several times, e.g. double looping doubles the sensitivity. The measuring range of the STWA4MH is reduced by multiple looping. To measure currents of any size, the STWA4MH is simply looped into the secondary circuit of a large current transformer with a secondary output of 5A (lead the cable through STWA4MH several times).

The STWA4MH enables the space-saving an cost-effective measurement of the actual value of an alternating current. Compared to transducers with analog output, the bus technology significantly  reduces the effort for the hardware (inputs) and the wiring. Applications are e.g. the recording of the current consumption of electrical motors in processing machines. Here the feed can be regulated depending on the load on the motor. Another example is the monitoring of consumers, e.g. heating elements, for failure.


Overview of Functions

  • Current measurement AC 0-60 A (RMS - Root Mean Square), resolution 1 mA
  • Actual value
  • Average over 200 ms
  • Average over 1 s
  • Measured values from the last 50 periods
  • Frequency measurement 40-70 Hz (sinus-shaped signals)
  • RS 485 interface (Modbus RTU)
  • Addressable for up to 246 participants
  • Baud rates 4800, 9600, 19200, 57600, 115200
  • Wiring effort minimized through bus technology
  • Supply voltage DC 24 V (10...30 V)
  • Connection via plug in spring type terminals
  • Lockable housing on mountin rail or screw fastening
  • Plug in current transformer (Ø 11 mm)

Technical Data

Rated supply voltage Us


DC 24 V, 10,0 ... 30,0 V, <0,25 W


Measuring input current


AC 0 ... 60 A, sinus shaped (RMS)


Error (from 1%/Inom)


± 0,1 % ± 200 mA.


Temperature coefficient


≤ 0,1 % / K




1 mA


Measurement time


1 period (40...70 Hz)


Overload constantly / 10 s


Inom + 20 % / AC 200 A


Measuring range frequency


40...70 Hz


Error (from 1%/Inom)


≤ 0,1 Hz




0,01 Hz


Rated insulation voltage


300 V


Rated ambient temperature range






Design H


Dimensions (h x w x d)


53 x 36 x 56 mm


Max.  Ø conductor


11 mm




ca. 90 g



Operating manual

Operating manual modbus

Software parameterization

Operating manual software



CE Decl. of conformity