Mitsubishi Electric Q68TD-G-H01 MELSEC Q Series Temperature Input Module

Description

Configured for precise thermal monitoring, the Mitsubishi Electric Q68TD-G-H01 delivers eight channel-isolated thermocouple inputs to high-reliability MELSEC Q Series control environments. This high-performance module is designed to eliminate ground loops and reduce noise interference in multi-point temperature measurement applications, making it highly suitable for demanding industrial processing plants. Each channel can be configured independently, allowing for versatile sensor integration across different thermocouple types within a single PLC rack footprint.

Features

• Channel-to-Channel Isolation: Complete galvanic isolation between input channels prevents ground loop electrical interference and protects sensitive control systems.
• Multi-Type Thermocouple Support: Directly compatible with standard thermocouple types B, E, J, K, N, R, S, and T.
• Compact System Footprint: Occupies only 16 I/O points on the MELSEC Q base unit, conserving valuable slot space.
• Integrated Diagnostics: Offers sensor wire breakage and disconnection detection to trigger immediate system alerts and prevent thermal runaway.

Applications

• Plastic extrusion, molding, and hot runner thermal profiling.
• Heat treatment, kilns, and annealing industrial furnace control systems.
• Multi-zone chemical reactor vessel temperature tracking.
• Boiler feed-water and steam temperature monitoring in utilities.

Technical Specifications

Empirical Engineering Insights

Alternative Models & Compatibility

The Q68TD-G-H01 offers upgraded channel-to-channel isolation compared to non-isolated temperature modules such as the standard Q64TD. When replacing older non-isolated versions, review rack power budgets, as the internal 5 VDC current consumption is significantly higher (0.49 A) due to the onboard isolation circuitry. Ensure your system's power supply module (e.g., Q61P) has sufficient remaining overhead.

Application Pitfalls & Engineering Notes

To prevent measurement drift in environments subject to rapid ambient temperature fluctuations, avoid mounting the module directly adjacent to heat-producing components like power supplies or motor starters inside the enclosure. Ensure that unused input channels are software-disabled in the module parameters to prevent false sensor wire-breakage alarms and unnecessary CPU diagnostics.

Commissioning & Wiring Tips

Always use dedicated thermocouple extension and compensation cables matching the thermocouple type (e.g., KX extension wire for Type K sensors). Keep these sensor wires routed away from high-voltage AC cables and variable frequency drive outputs to minimize electromagnetic induction. Ensure shield wires are terminated at a single, clean instrumentation ground point near the PLC rack.

Installation Guidelines