Selectivity and Fast Fault-Locating in 24V DC Load Circuits

The selectivity and diagnostics modules are the optimum extension for all 24 V DC power supplies. They distribute and monitor the load current over several current circuits. Overloads and short circuits on a circuit are reliably recognized.

The electronics permit brief current peaks caused, for example, by high inrush currents, but isolate 24 V DC load circuits in the event of an extended overload. This is ensured even on high-resistance lines and in the case of "creeping" short circuits. In such cases, miniature circuit breakers fail to trip, or trip too late, even if the power supply unit could deliver the required tripping current. The intact load circuits continue to supply the SITOP add-on module with 24 V DC without interruption or interaction whatsoever and thus avoid what could otherwise be a complete failure of the system.


The SITOP PSE200U selectivity module with single-channel signaling allows channel-specific and fast fault location via one single digital input of the PLC.

Function blocks perform the evaluation for SIMATIC S7-1500/1200/300/400 for STEP 7 and TIA Portal and for SIMOTION SCOUT, SIMOTION controller and LOGO!. This allows easy integration into S7 diagnostics and higher-level control, operating and monitoring systems.

Your advantages with SITOP PSE200U at a glance

  • Reliable tripping, regardless of the cable lengths or cable cross-sections

  • Four 24 V DC load feeders per module, in two versions with adjustable output current range of 0.5-3 A and 3-10 A

  • Variants with power limitation for the outputs to 100 VA according to NEC Class 2

  • Easy configuration using individual setting of the maximum current via potentiometer for each channel

  • Two versions for remote diagnostics: common signaling contact or single channel signaling

  • Evaluation via free SIMATIC S7 function blocks (S7-1500/1200/300/400) for modules with single-channel signaling

  • Library for visualization in SIMATIC PCS 7

  • LEDs for fast fault location on site

  • Remote reset possible from centralized location

  • Easy commissioning using manual on/off switching of channels with reset button

  • Voltage measuring points for output current  (1 V = 1 A), no separation of the circuits required

  • Sequential connection delay of individual 24 V DC load circuits reduces total inrush current

  • Sealable transparent cover protects against maladjustment of tripping current and sequential delay