The current relay STW12 monitors the current flow yes/no of up to 12 alternating-current circuits. If there is an AC-current of ≥1 A through a connected transformer STWA 1, the according output transistor switches and the yellow LED lights up. 

All the OR inputs are linked at the same time. If a current is identified in at least one of the monitored current circuits, a relay (1 changeover contact) picks up. 

The STW12 is installed at an open printed circuit board. The lower part can be used for snapfastening on a 35 mm DIN-rail or for screw fastening (option). The supply voltage is DC 24. This voltage can be used at the same time for inquiry of the output transistors. When requesting the outputs in 2 groups in multiplex operation, only 8 I/Os of the PLC are needed.

• 12 inputs (for transformer STWA1)
• 2 of these inputs with adjustable switching threshold AC 0,5...5 AA
• 12 outputs (Open Collector) max. DC 40 V/40 mA
• relay OR-linked (of all 12 inputs)
• LED displays (1/channel)
• Multiplex operation possible

Applications
The current relay STW12 is used where AC-current yes/no has to be evaluated, however, the exact value of the current is not relevant. Examples are the control of machines in suction plants or monitoring of the mode of operation of loads (on, off or damaged). The STW12 is suitable in particular for being used in connection with a PLC.