Description
Pilz PNOZ s4 750104 | 24VDC PNOZsigma Safety Relay
Product Introduction
When an emergency stop button is pressed or a safety gate is opened on a high-speed packaging line, the safety interlock must instantly cut power to all dangerous motion. The Pilz PNOZ s4 (750104) isn’t a standard industrial switching relay; it is a certified safety relay base module engineered specifically to achieve the highest safety performance levels (Category 4 / PL e / SIL CL 3) across industrial automation bays. Attempting to use non-safety-rated control relays for emergency stop circuits violates international machine safety standards and exposes operating personnel to severe injury risks—making this exact PNOZsigma module critical for plant safety compliance.
Operating inside narrow control enclosures requires maximum space efficiency and low thermal output. The PNOZ s4 packs dual-channel input monitoring, cross-circuit fault detection, and high-current safety contacts into a ultra-slim 22.5mm housing. Built-in rotary setting switches allow field technicians to toggle between manual, monitored, and automatic start modes—though you must always double-check your reset loop configuration to prevent unexpected automated restarts after clearing E-stop conditions.
PNOZ S4 750104
Key Technical Specifications
- Manufacturer & Part Number: Pilz 750104 (PNOZ s4 24VDC 3 n/o 1 n/c)
- Supply Voltage (UBU_BUB): 24 V DC
- Power Consumption: Approx. 2.5 W
- Safety Contacts: 3 Safety-Oriented Normally Open (N/O) contacts (AgCuNi, gold-plated options)
- Auxiliary Contacts: 1 Auxiliary Normally Closed (N/C) contact
- Semiconductor Outputs: 1 Auxiliary semiconductor diagnostic output
- Operating Modes: Single-channel, dual-channel with cross-circuit detection, manual start, monitored start, automatic start
- Safety Rating: SIL CL 3 (EN 62061), Performance Level e (EN ISO 13849-1), Category 4 (EN 954-1)
- Response Time / Release Time: 10 ms / 20 ms
- Housing Width: 22.5 mm DIN-rail mount (35mm)
- Connection Type: Screw terminals (plug-in terminal block design)
- Operating Temperature Range: -10°C to +55°C (14°F to 131°F)
Application Scenarios & Pain Points
A high-speed bottling facility in Texas experienced recurring line halts caused by intermittent cross-circuit fault trips on an aging safety door interlock circuit. Replacing the legacy relay with a fresh Pilz PNOZ s4 750104 restored clean dual-channel pulse evaluation, eliminating false safety trips and securing full machine safety compliance.
With vs. Without Certified Safety Relays:
- Without the PNOZ s4 750104: Standard switching relays can weld their contacts together under electrical overload, failing to open when an emergency stop button is pressed.
- With the PNOZ s4 750104: Force-guided positive-action contacts guarantee that if a contact welds, downstream safety circuits remain open and lock out machine restart.
Automotive Assembly & Robotic Work Cells:
- Condition: Multi-shift automated cells featuring light curtains, perimeter safety gates, and E-stop palm buttons.
- Impact: Electrical transients and contact bounce lead to safety relay lockouts and unnecessary production downtime.
- Solution: Deploying the PNOZ s4 with active cross-circuit detection locks down reliable, vibration-immune safety circuit evaluation.
QA & Live Testing SOP (Trust Signal)
Every Pilz PNOZ s4 750104 unit entering our facility undergoes a strict, multi-point safety validation protocol. We begin with a full visual and mechanical inspection of the DIN-rail mounting clip, terminal blocks, rotary mode switches, and LED indicator light pipe windows. Next, the relay is mounted on a test panel and powered with a regulated 24VDC bench supply—we verify internal voltage regulation using a calibrated Fluke multimeter.
During live functional testing, we wire dual-channel E-stop inputs and execute manual and automatic reset sequences. We verify force-guided contact opening time, test short-circuit detection across input channels, and confirm that the auxiliary diagnostic semiconductor output toggles state accurately. Once cleared, the relay is wiped clean, fitted with terminal protective caps, and vacuum-sealed in ESD protective packaging with custom foam cushioning.
Field Engineer’s Pitfall Guide
❗ GOTCHA #1: Rotary Switch Mode Setting Selection Do not change the front-panel rotary operating mode switch while the unit is energized. The PNOZ s4 reads switch settings only during initial power-up; changing modes live will cause the unit to report a configuration fault and flash its LED status indicators.
❗ GOTCHA #2: Monitored Start vs. Automatic Start Jumpers When wiring a manual E-stop circuit, ensure you select Monitored Start (S34 connected to feedback loop) rather than Automatic Start. Using Automatic Start on an E-stop button will cause the machine to restart instantly as soon as the button is pulled out, creating a major safety hazard.
❗ GOTCHA #3: Cross-Circuit Detection Jumper Setup When connecting dual-channel safety devices (like light curtains with OSSD outputs), turn off the module’s internal cross-circuit detection mode. Light curtain OSSD outputs generate their own test pulses; enabling cross-circuit detection on the relay simultaneously will cause channel synchronization faults.
Intent-Driven FAQ
What does “Mushroom” mean in reference to the PNOZ s4 750104?
“Mushroom” is a common direct translation or auto-correct for the German safety automation manufacturer Pilz (which translates to mushroom in German). The product is manufactured by Pilz GmbH & Co. KG.
What is the primary application for the Pilz 750104 PNOZ s4?
The PNOZ s4 (750104) is a universal safety relay used to evaluate emergency stop buttons, safety gate switches, light curtains, and two-hand controls in automated machinery.
Can I expand the output contacts of the PNOZ s4?
Yes. The PNOZsigma series allows side-by-side contact expansion modules (such as the PNOZ s7 or PNOZ s8) to be snapped directly onto the right side of the PNOZ s4 base unit using the integrated PNOZsigma connector.
What do the LED indicators on the front panel mean?
- POWER: Green indicates 24VDC supply voltage is applied.
- IN1 / IN2: Green indicates input channel 1 and channel 2 are closed/active.
- START: Green indicates the start circuit is closed.
- FAULT: Red indicates an internal or external cross-circuit or wiring fault.
Is the PNOZ s4 750104 interchangeable with older PNOZ X4 relays?
While both perform emergency stop monitoring functions, the PNOZ s4 belongs to the compact PNOZsigma family (22.5mm width with rotary mode selection), whereas the older PNOZ X4 uses a wider housing format. Wiring connections and terminal layouts must be verified before retrofitting.
