zQ 900-11 - Mechanical Interlock 3-Contact Redundant - SS IP67 Industrial Safety Switch

1. ​Product Overview​

The Schmersal zQ 900-11 is a high-security safety switch engineered for critical applications requiring deliberate restart authorization. Featuring a ​stainless steel housing (IP69K rated)​, this device integrates ​encrypted RFID-coded magnetic actuation​ with ​key-operated manual reset functionality. Certified to ​ISO 13849-1 PL e (Category 4)​​ and ​IEC 62061 SIL 3, it utilizes ​positively driven force-guided contacts​ that guarantee safe-state operation during component failures. Designed for extreme industrial environments (-40°C to +85°C), its hermetically sealed construction withstands 150-bar washdowns, chemicals (pH 0-14), and mechanical impacts (IK10). The integrated ​tri-color LED indicators​ provide 360° visibility of guard position, reset status, and diagnostic alerts. The manual reset function prevents automatic restart after safety activation, requiring physical key intervention to restore machine operation.

2. ​Key Technical Parameters​

• ​Safety Ratings:
  • PL e (ISO 13849-1 Cat. 4, DCavg=99.8%)
  • SIL 3 (IEC 62061, PFHD: 1.5×10⁻⁹/h)
  • ATEX Zone 1/21
• ​Electrical Specifications:
  • Voltage: 24V DC ±10% (19.2-28.8V)
  • Contacts: 3 NC force-guided (10A @ 250V AC)
  • Reset Current: <0.5A
• ​Mechanical:
  • Switching Distance: 8mm ±0.5mm
  • Locking Force: 1,500N holding
  • Reset Torque: 0.8-1.2Nm
• ​Environmental:
  • IP69K (100°C/150 bar washdown)
  • Chemical Resistance: Resists acids/alkalis
• ​Certifications:
  • UL 508, CSA C22.2 No. 14
  • IECEx Ex db IIC T6 Gb

3. ​Primary Applications​

This switch is essential for hazardous processes requiring controlled restart:

• ​Chemical Reactors: Prevents unauthorized restart after maintenance
• ​Power Presses: Ensures operator clearance before cycle initiation
• ​Robotic Cells: Requires safety confirmation after E-stop activation
• ​Plastic Injection: Mold area access with reset accountability
• ​Steel Rolling Mills: Prevents restart during roll change procedures
• ​Pharmaceutical Isolators: GMP-compliant access control
• ​High-Voltage Cabinets: Ensures lockout/tagout compliance
• ​Mining Crushers: Prevents activation during maintenance
  Its manual reset function provides an additional layer of safety where automatic restart could endanger personnel during intervention or maintenance activities.

4. ​Functional Advantages​

• ​Controlled Restart Security:
  • Key-operated reset prevents unauthorized reactivation
  • Audit trail via physical key accountability
• ​Tamper Resistance:
  • 128-bit encrypted RFID pairing
  • Torque-monitored security screws (5Nm)
• ​Diagnostic Intelligence:
  • Green LED: Guard closed/secure
  • Yellow LED: Reset required
  • Red LED: Critical fault
• ​Harsh Environment Resilience:
  • Electropolished SS316L housing
  • Viton® seals for steam/chemical resistance
• ​Safety Redundancy:
  • Triple NC contacts with cross-monitoring
  • Mechanical contact separation >0.8mm
• ​Maintenance Optimization:
  • Tool-free contact block replacement

  1 million mechanical cycles

5. ​Safety Operation & Reset Protocol​

​Safety Activation Sequence:

1. ​Guard Opening:
   • Magnetic field disruption opens NC contacts
   • Machine enters safe state (Stop Category 0)
2. ​Manual Reset Requirement:
   • Physical key insertion and 45° rotation
   • System performs self-test (contact verification)
3. ​Safety Restoration:
   • Valid self-test closes NC contacts
   • Green LED confirms operational status

​Diagnostic Monitoring:

• ​Position Verification:
  Hall sensors track actuator position (±0.2mm)
• ​Contact Integrity:
  Current sensors detect welding anomalies
• ​Reset Security:
  Key cannot be removed in intermediate positions

​Fault Response Hierarchy: