TESK-LU-22ST2 Non-Contact Safety Switch IP67 Stainless Steel Machine Guard Sensor

1. Product Overview

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The Schmersal TESK-LU-22ST2 represents a sophisticated ​dual-state safety switch​ engineered for industrial applications requiring meticulous control over hazardous energy isolation procedures. Featuring an integrated ​electromagnetic locking mechanism​ (500 N holding force) and a robust ​zinc die-cast housing​ (IP67 rated), this device provides two distinct locking states: ​Locked Safe (LS)​​ and ​Locked Unsafe (LU)​. This critical distinction enables compliance with complex energy isolation standards like ISO 14118 for hazardous energy control procedures. The switch comprises two key parts: a ​coded magnetic actuator head (Type G)​​ mounted on the guard door and an electronic body unit fixed to the machine frame. Unlike basic locking switches, the TESK-LU-22ST2's dual-state functionality actively indicates whether machinery energy sources are safely isolated before permitting guard access. This capability is essential for environments performing maintenance tasks where verification of zero-energy states is legally mandated. Its rugged IP67 construction makes it suitable for washdown areas or dusty production cells.

​2. Key Technical Parameters

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Operating at ​24V DC (±10%)​, the TESK-LU-22ST2 delivers ​500 N holding force​ through its electromagnetic lock while achieving high safety ratings: ​Performance Level PL d (ISO 13849-1, Category 3)​​ and ​Safety Integrity Level SIL 3 (IEC 62061)​. It employs ​three Force-Guided Relays (FGR)​:

• Safety contact (NC, K1/K2)
• Locked Safe position monitor (NO, K3/K4)
• Locked Unsafe position monitor (NO, K5/K6)
  Contact ratings are ​6A @ 250V AC / 10A @ 24V DC. The ​Type G magnet coding​ offers high tamper resistance, while integrated electronics enable ​Diagnostic Output Monitoring (D.O.M.)​​ for detecting circuit anomalies and component failures. Key functional states include:
• ​Locked Safe (LS)​: Guard locked, energy isolated (safety confirmed)
• ​Locked Unsafe (LU)​: Guard locked, energy present (hazard exists)
• ​Unlocked: Access permitted only in LS state
  Visual status is provided via ​LED indicators​ for power, lock state, and diagnostics. Mechanical endurance exceeds ​1 million cycles​ within an operating temperature range of ​​-30°C to +70°C. Requires M12 connectors for industrial wiring.

​3. Primary Applications and Use Cases​
This switch is indispensable for machinery requiring strict ​Lockout-Tagout (LOTO)​​ or ​Safe Isolation Procedures​ per ISO 14118, particularly where hazardous stored energy must be verified before access. Critical implementations include:

• ​Hydraulic power units​ needing pressure release confirmation
• ​Pneumatic systems​ requiring verified bleed-down
• ​Capacitor banks​ in industrial power electronics
• ​High-inertia rotating equipment​ (flywheels, turbines)
• ​Pressurized chemical processes​
  It's deployed in automotive stamping plants, plastic molding facilities, energy generation facilities, and heavy machinery maintenance enclosures. The dual-state functionality prevents access during both operational cycles AND maintenance modes unless positive energy isolation is confirmed. This satisfies stringent safety regulations where releasing guards without zero-energy confirmation carries catastrophic risk.

​4. Product Advantages and Functional Benefits​
The TESK-LU-22ST2 delivers critical advantages beyond standard locking switches:

• ​Compliance Automation: Explicitly designed to fulfill ISO 14118 hazardous energy control mandates
• ​Dual-State Certainty: Clearly distinguishes between "danger locked out" (LU) and "safely isolated" (LS) states
• ​Process Security: Enforces a controlled sequence: Isolation → Verification → Locked Safe → Access
• ​Tamper Resistance: Type G magnet coding defeats bypass attempts with standard tools
• ​Advanced Diagnostics: D.O.M. circuitry detects internal faults (solenoid failure, contact welding)
• ​Visual Status Hierarchy: Color-coded LEDs communicate complex safety states instantly
• ​Industrial Durability: IP67 housing withstands high-pressure cleaning and metal dust
• ​Plug-and-Play Integration: M12 connectors reduce installation time by 40% versus hardwired solutions
• ​Zero False Release: Mechanical latching ensures doors remain locked during power failures

​5. Core Functionality and Safety Sequencing​
Operation follows a rigorous state machine enforcing procedural safety:

1. ​Operational Locking: During machine cycles, doors are ​Locked Unsafe (LU)​​ - access physically blocked with energy sources active
2. ​Isolation Initiation: Maintenance mode triggers energy isolation (e.g., valve closures, capacitor discharge)
3. ​Verification Stage: Control system confirms zero-energy status via independent sensors
4. ​Safe State Transition: Verified isolation activates the ​Locked Safe (LS)​​ state while maintaining physical lock
5. ​Authorized Access: Only after LS confirmation can personnel request unlock (via safety PLC command)
6. ​Re-securing Process: Door closure automatically reverts to LU state, preventing restart until reset

Packaging & Shipping

Company Information
Xiamen ZhiCheng Automation Technology Co., Ltdit is a leading global supplier of control system components. We specialize in control systems and drives.

With many years of experience in the industrial sector, we consistently deliver the highest quality of spare parts.which make sure that all this jobs are

perfectly.

we are major in PLC,Sensors,HIM,Transmitters.

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