Recision Original New Safety Relay PILZ PNOZ 16SP 787070 High Performance for Industrial Equipment

Machine safety is one of those disciplines where “mostly works” is the same as “eventually hurts someone.” The Pilz PNOZ 16SP family exists to make the safety side boring: it provides a safety-related interruption of a safety circuit and is intended for classic guard and emergency-stop architectures where reliability and diagnostic coverage matter. In the PNOZ 16SP lineup, order number 787070 is the “C” connection variant with spring-loaded (cage clamp) terminals, used for the 24 VAC/DC version. 

PNOZ 16SP is designed for use in applications such as E-STOP pushbuttons, safety gates, pressure sensitive mats, and pressure sensitive edges, meeting relevant requirements (as described in the operating documentation). 

What makes this relay practical in the real world is that it supports both straightforward safety wiring (single-channel) and more diagnostic-rich wiring (dual-channel with detection), includes a feedback loop for external device monitoring, and offers semiconductor signaling outputs so you can feed status into a PLC/HMI without “stealing” your safety contacts.

What the 787070 Variant Means

Pilz uses the same PNOZ 16SP core safety function across multiple supply versions and connection types. In the order reference, Pilz lists:

• 777070: PNOZ 16SP 24 VAC/DC, screw terminals

• 787070: PNOZ 16SP C 24 VAC/DC, spring-loaded / cage clamp terminals 

So, when you specify 787070, you are primarily choosing the terminal technology (spring-loaded) while staying within the 24 VAC/DC supply version of PNOZ 16SP. 

Core Safety Function and Operating Logic

PNOZ 16SP is built around a redundant, self-monitored safety concept: the unit is designed so the safety function remains effective even if a component fails, and relay operation is checked automatically in each switching cycle. 

In operation, the relay becomes ready when two things are satisfied:

1. The feedback loop is closed (Y1–Y2).

2. The start circuit is closed (S33–S34). 

When the input circuit is healthy (for example, the E-STOP is not pressed), the safety contacts close and the unit is active. If the input circuit opens (for example, E-STOP pressed or a safety gate opens), the safety contacts open redundantly. 

PNOZ 16SP also provides two semiconductor outputs for signaling:

• One indicates the switch state of the safety contacts (documented as Y32).

• Another indicates a “short across contacts”/fault-related signal (documented as Y35, including the note about supply/fuse condition). 

Operating Modes You Can Design Around

PNOZ 16SP supports multiple operating approaches, which is handy when you’re modernizing a machine but must keep proven wiring patterns:

• Single-channel operation (simpler, but with less redundancy in the input circuit).

• Dual-channel operation with detection of shorts across contacts, where the relay detects earth faults, short circuits in the input circuit, and shorts across contacts in the input circuit. 

• Automatic start or manual start, depending on whether you want the safety outputs to energize automatically after the input circuit becomes healthy, or only after an intentional reset/start action. 

For pressure sensitive mat applications, the documentation describes behavior where actuation can create a short condition that triggers internal fault detection, opens the safety contacts, and requires recovery time before returning to ready state. 

Important integration detail: the device documentation notes that short circuits/shorts across contacts in the start/feedback loop are not recognized by the device and must be handled via wiring measures or fault exclusion practices. 

Technical Summary (24 VAC/DC Version Context for 787070)

The operating manual provides detailed technical data for the 24 V variant (Order no. 777070); since 787070 is the same 24 VAC/DC version with spring-loaded terminals per the order reference, this table is the practical “engineering baseline” most buyers expect when selecting 787070. 

Terminals and Signals at a Glance

Why Buyers Choose PNOZ 16SP 787070

1. Fast, tidy wiring in panels: spring-loaded terminals reduce re-torque checks and are friendlier in vibration-prone cabinets compared with traditional screw terminals (selection reason: connection technology). 

2. Clear status feedback without extra relays: semiconductor outputs give you diagnostics to a standard PLC input without consuming the safety contacts. 

3. Versatile safety inputs: supports E-STOP, guards, and pressure mats/edges in one proven relay platform. 

4. Structured commissioning: defined feedback loop and start circuit logic helps create a repeatable validation checklist. 

Typical Commissioning Checklist (Practical, Not Fancy)

1. Mount the relay on DIN rail in a cabinet with appropriate protection (the documentation provides installation guidance, including cabinet protection expectations). 

2. Wire the safety input(s) as single-channel or dual-channel per your risk assessment, and wire Y1–Y2 feedback plus S33–S34 start logic. 

3. Confirm safety contact behavior on demand (E-STOP pressed, gate open, mat actuated) and verify semiconductor status signals behave as expected. 

4. Document the test results as part of the overall machine safety validation (the manual stresses that overall machine functional safety depends on the complete safety function, not just the component). 

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