Current-Relay STW20V

Current Relay for AC-Detection, AND-Evaluation, 3 Transformers

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Part number

AC/DC 24 - 240 V

Product description


The current relay STW20V monitors the current in up to 3 lines with current transformers STWA 1 (AND circuit). If there is a current in all 3 monitored lines, the relay (2 change-over contacts) picks up. If there is no current in at least one of the lines, the relay releases.

The relay works in closed circuit current. When voltage is applied to the STW, the relay signals an alarm until the it has picked up. This can be avoided if the device is constantly alive and monitoring is started by closing a contact at the Enable input. With a bridge at the Enable input, monitoring is automatically started when voltage is applied.

  • 3 inputs (transformer STWA1)
  • 3 x current-sensor S1 (powersupply required)
  • AND-evaluation
  • output relay 2 CO
  • switching point app. AC 1 A
  • Enable-input
  • storage of alarms or Auto-Reset
  • LEDs power on and alarm 
  • housing V4 for mounting on DIN-rail or wall-mount


Identifies power failure with 1- or 3-phase electrical consumers, e.g. with monitoring of heating elements or heating installations where a constant heating has to be guaranteed.

A further application is the identification of phase failure, monitoring of fuses, or triggering of operating hours counters.


Technical Data

Power supply Us


AC/DC 24 - 240 V, < 3 W, < 5 VA,
(AC 20 - 264 V, DC 20,4 - 297 V) AND-evaluation






Transformer input


1 or 3, type STWA 1


Overload cap. continious/max.10s


100A / 300 A


Switching point on


≤ AC 1 A


Switching point off


≥ AC 0,3 A


Switch-off delay


approx. 0,3 s.


Switch-on delay


approx. 0,3 s.


Output relay


2 CO


Type of contact


type 2 see general technical informations


Testing conditions


see general technical informations


rated ambient temperature range




Dimensions H x B x T


Design V 4: 90 x 70 x 58 mm


Protection housing / terminals


IP 30 / IP 20




approx. 240 g