STWA1S, Electronic Current Transformer, AC-current-detection >2 A

STWA1S, Electronic Current Transformer, AC-current-detection >2 A
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  • S225195
AC-current-detection 2 A yes/no potential-free transistor-output max. DC 40V/40 mA no... more

AC Electronic current transformer with transistor-output (not for connection to current relays type STW)


The STWA1S has an integrated electronic with transistor-output. The switching point is 2 A. Above app. 2 A the output transistor is switched on (LOW), below app. 1.5 A it is off (HIGH). The conductor is simply pushed through the transformer.Multiple loops reduce the switching point correspondingly, for instance to 0.5 A with four loops. A supply voltage is not required.


The STWA1S is used where current flow is to be detected, with the exact value of the current either known from the power consumption of the connected consumer or does not matter for the evaluation.
For simultaneous evaluation of the current flow in several conductors the STWA1S device can be connected in series (AND circuit, pay attention to the voltage drop) or in parallel (OR circuit, pay attention to the leak current).

  • isolated transistor-output max. DC 40 V/40 mA
  • output can be directly connected to the digital input of a PLC
  • integrated diode for reverse voltage protection
  • 2-wire-connection, 1 m
  • no supply voltage required
  • transformer and electronic unit enapsulated in a climate-proof housing
  • plug-in current transformer (Ø 11 mm)
  • max. overload 100 A continously, 300 A / 10 s

Technische Daten

Switching point at Tu = 25°C


AC 2 A +20/-40%




approx. 6%


Repeat accuracy


±5 %


Temperature dependence


0...55°C: <0,5%/K (-20...0°C: <2,5%/K)


Temperature dependence


100 A/ 300 A


Output voltage/current max.


DC 40 V / 40 mA


Voltage drop (ON)


max. 3 V


Leak current (OFF)


max. 0,6 mA


Switch-on /switch-off delay

....... 50 / 200 ms


nominal frequency/ operating range


50 Hz/ 30...70 Hz




≤ 1 %/Hz


rated ambient temperature range


-20...+55 °C




Design S


Dimensions (Ø x H)


34,5 x 27 mm


Diameter for conductor


11 mm




app. 60 g

Input / measuered parameter: Current detection yes/no
Outputs: Digital outputs
Design: Mount in switchgear cabinet
Extras: Current transformers
Applications: Controils for suction plants, Control for trace heating