PNOZ-X2.8P-777301 PILZ Safety Relay

PNOZ-X2.8P-777301-PILZ is the most widely used dual-channel safety relay from Pilz’s PNOZ X product line. Its core advantages cover wide 24V AC/DC operating voltage, 3NO+1NC contact configuration, high safety rating of SIL 3 / PL e, and ultra-fast response within ≤50ms. It is extensively deployed for various industrial safety monitoring applications. Thanks to hardwired design, it delivers superior reliability over software-based solutions under high-vibration and severe EMI conditions, making it an optimal choice for industrial automation safety protection.

Model Code Breakdown

Code Segment	Definition	Detailed Description
PNOZ	Product series prefix	Identifier for Pilz core safety relay product range
X	Series code	Basic standalone safety relay of PNOZ X series, operable without extension modules
2.8	Functional code	“2” stands for dual-channel monitoring; “8” denotes automatic / monitored start mode with 3 safety outputs plus 1 auxiliary output
P	Termination type	Screw terminal version; Push-in indicates spring-cage pluggable terminals, unmarked for standard terminals
777301	Order number	Unique global part number for purchasing and inventory management
PILZ	Brand name	Pilz GmbH & Co. KG, Germany

Core Technical Specifications

Parameter Category	Specification	Remarks
General Data
Product Type	Dual-channel safety relay	Compliant with EN ISO 13849-1 (PL e) & EN 62061 (SIL 3)
Rated Supply	24V AC/DC (±15%)	Wide-range input compatible with standard industrial power supplies
Dimension	94×22.5×121mm (H×W×D)	22.5mm standard width for compact cabinet layout
Mounting	35mm DIN rail (EN 60715)	Vertical installation, tightening torque: 0.5~0.8Nm
Input Characteristics
Input Circuits	2 independent dual-channel inputs (S11-S12/S52, S21-S22)	24V DC, 30mA input, compatible with PNP sensors
Input Function	Optional cross-contact short-circuit detection	Enabled by short-circuiting S11-S12; disabled by short-circuiting S21-S22
Output Characteristics
Safety Outputs	3 Normally Open (NO) contacts with redundant dual-contact series design	Redundant structure for guaranteed safe cut-off
Auxiliary Output	1 Normally Closed (NC) contact	For status indication only, NOT permitted in safety circuits
Contact Rating	AC1:240V/6A; DC1:24V/6A	AgCuNi silver-copper-nickel contact material for arc oxidation resistance
Contact Rating	AC15:230V/5A; DC13:24V/5A
Performance Parameters
Response Time	≤50ms (input to output); reset time ≤100ms	Fast safety cut-off for high-speed machinery
Power Consumption	Max.100mA	Low-power design for energy saving
Ambient Temperature	Operation: -10°C ~ +55°C; Storage: -35°C ~ +70°C	Suitable for harsh industrial ambient conditions
Ingress Protection	IP20 (main body), IP40 (terminal area)	Must be installed inside control cabinet ≥IP54
Certifications	CE, CCC, UL, RoHS	Global market access certifications

III. Full Range Model List (Core PNOZ X2 Series)

Model	Order No.	Supply Voltage	Output Configuration	Start Mode	Terminal Type
PNOZ X2.8P	777301	24V AC/DC	3NO+1NC	Automatic / Monitored	Screw
PNOZ X2.8	777300	24V AC/DC	3NO+1NC	Automatic / Monitored	Standard
PNOZ X2.8P PI	777302	24V AC/DC	3NO+1NC	Automatic / Monitored	Plug-in
PNOZ X2.7P	777311	24~240V AC/DC	3NO+1NC	Automatic / Monitored	Screw
PNOZ X2.7	777310	24~240V AC/DC	3NO+1NC	Automatic / Monitored	Standard
PNOZ X2.10P	777321	24V DC	2NO+1NC	Manual Reset	Screw
PNOZ X2.11P	777331	24V DC	3NO+1NC	Manual Reset	Screw

Cross-Brand Equivalent Replacement Table

Brand	Alternative Part	Key Differences	Application Scope
Schneider	Zelio SR2B121BD	Single-channel, 2NO+1NC, 24VDC only	Low-risk applications with limited budget
Siemens	3SK1111-1AB30	Dual-channel,3NO+1NC,24V AC/DC	Full drop-in replacement, SIL3 compliant
Omron	G9SA-321-T075	Dual-channel,3NO+1NC,24V AC/DC	Matched for Japanese-built equipment, cost-effective
ABB	MSR125TP	Dual-channel,3NO+1NC,24V AC/DC	Heavy-duty machinery with superior anti-vibration performance
Pilz Upgrade	PNOZ X2.7P (777311)	Wide voltage:24~240V AC/DC	Global projects with varying supply voltages

Application Environment & Industry Cases

Recommended Applications

Machinery Safety Monitoring: Emergency stop pushbuttons, safety door interlocks, safety light curtains, two-hand control stations
Automotive Manufacturing: Welding robots, coating production lines, lithium battery equipment interlock control
Electronics Assembly: SMT placement machines, AOI inspection equipment, laser cutter safety circuits
Packaging Machinery: High-speed packaging lines, palletizing robots, over-temperature protection for heat-sealing devices
Logistics Automation: Stacker cranes, AGVs, conveyor safety door & E-stop systems

Non-Recommended Applications

Safety systems requiring complex logic operations (PNOZmulti modular safety controller recommended)

Extreme high-vibration environments (>10g): extra vibration dampening required

Unprotected outdoor mounting (only IP20 body protection)

Typical Application Cases

Case1: Lithium Battery Aging Room Safety Control for Automotive Industry

Functions: Access door interlock, emergency cut-off on over-temperature, fire protection linkage

Configuration: PNOZ X2.8P(777301)+safety door switch+temperature sensor+E-stop button

Outcome: PL e safety level achieved to prevent thermal runaway of lithium cells

Case2: Safety Circuit Retrofit for Laser Cutting Machine

Original Issue: Distributed safety PLC I/O triggered false shutdown twice in three years due to EMI interference

Solution: Replace with hardwired safety circuit using PNOZ X2.8P

Result: Zero breakdown over 5 years, response optimized ≤50ms, maintenance cost cut by 60%

Selection Tips & Quick Reference Rules

Quick Selection Formula

24V AC/DC X2.8, dual-channel with three NO & one NC<br>

Screw terminal 777301, automatic start with top safety grade<br>

E-stop, light curtain & safety door, certified SIL3 & PL e<br>

DIN rail mounting saves cabinet space, fits all industrial sites

Quick Reference Rules

Model Memorization: PNOZ X2.8P = Dual-channel + Mode8 + P=screw terminals
Order Code:777301 = standard baseline part of Pilz X2 family
Core Specs:24V AC/DC,3NO+1NC,≤50ms response,SIL3/PL e
Terminal Wiring Rules:

Short S11-S12: Activate contact short-circuit detection

Short S21-S22: Deactivate contact short-circuit detection

Short S12-S34: Enable automatic start mode

Short S52-S11: Enable automatic reset function

VII. Installation & Maintenance Guidelines

Installation Specifications

Mount vertically inside control cabinet with terminals facing upward for natural convection cooling
Maintain ≥50mm clearance from heat-generating components, ≥30mm from cabinet inner walls
Separate wiring of safety circuits and power circuits; route crossing wires at 90° to reduce EMI coupling
Install 10A fuse in series ahead of output contacts for contact protection

Common Troubleshooting Guide

Fault Phenomenon	Root Cause	Remedial Action
Power indicator off	1. No power supply or reversed polarity	1. Verify A1/A2 wiring
Power indicator off	2. Input voltage out of tolerance	2. Confirm stable 24V AC/DC supply
Safety outputs fail to close	1. Open input circuit	1. Check continuity of S11-S12/S21-S22
Safety outputs fail to close	2. Incorrect start circuit configuration	2. Confirm jumper status of S12-S34
Contact ablation/burning	1. Overloaded output rating	1. Upgrade to higher-rated relay
Contact ablation/burning	2. Missing snubber for inductive loads	2. Fit freewheeling diode(DC) or varistor(AC) in parallel
Unexpected false tripping	1. Electromagnetic interference on input lines	1. Apply shielded cable with proper grounding
Unexpected false tripping	2. Misconfigured short-circuit detection	2. Adjust S11-S12/S21-S22 jumper setup