Siemens SIMATIC S7-1500R/H Getting Started page 18

Connect light control function
The following figure shows the wiring of the fan control on the DQ 4x24VDC/2A ST digital
output module
The direction of rotation of the fan (right/left) is controlled via a reversing contactor:
● Fan rotates clockwise → Contactor K1 actuated
● Fan rotates counterclockwise → Contactor K2 actuated
The speed (high/low) of the fan is controlled via a Dahlander circuit:
● Fan low speed → Contactor K5 actuated
● Fan high speed → Contactors K3 and K4 actuated
Figure 1-7
S7-1500R/H redundant system
Getting Started, 10/2018, A5E44910930-AA
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Wiring of fan control
Introduction to the example
1.5 Wiring diagram for a tunnel section
17