1756-TBCH Rockwell Automation Cage Clamp Removable Terminal Block

Product Description

The Allen-Bradley 1756-TBCH is a high-density, 36-pin Removable Terminal Block (RTB) that provides the primary wiring interface for Allen-Bradley ControlLogix I/O modules. By acting as a detachable bridge between field devices and the PLC hardware, this component allows maintenance teams to replace I/O modules without disconnecting individual field wires, significantly reducing system downtime.

Product Overview

The 1756-TBCH belongs to the ControlLogix family of accessories, specifically engineered to streamline the installation of high-point-count digital and analog modules. This terminal block utilizes a cage-clamp mechanism to secure field conductors, ensuring a gas-tight and vibration-resistant connection. It plugs directly into the front of the 1756 I/O modules, providing a modular architecture where the wiring remains permanent while the electronics remain swappable. This design philosophy protects the integrity of the field signals during hardware upgrades or troubleshooting cycles.

Technical Specifications

Engineering Advantages

The 1756-TBCH offers distinct mechanical advantages for complex automation cabinets where space and reliability are paramount. The cage-clamp design facilitates faster termination compared to traditional screw-type terminals, as it maintains constant tension on the wire to prevent loosening caused by thermal cycling or industrial vibration. Furthermore, the 36-pin density supports sophisticated modules such as the 1756-OB16IEF or 1756-IA16I, allowing for a concentrated concentration of I/O points within a single chassis slot. Transitioning to this RTB also simplifies the commissioning process by allowing for pre-wiring of the terminal blocks before the actual PLC modules arrive on-site.

Installation and Field Wiring

Successful deployment of the 1756-TBCH requires adherence to specific conductor guidelines to ensure signal stability. Engineers should utilize solid or stranded copper wire rated for at least 90°C to withstand the localized heat generation typical of high-density I/O racks. The terminal block accommodates up to two conductors per terminal when using the appropriate wire gauges, providing flexibility for daisy-chaining power or common signals. During installation, the RTB snaps into the module housing and secures via top and bottom locking tabs, ensuring that the electrical contact remains consistent even in high-vibration environments.

FAQs

• Can I use the 1756-TBCH with any ControlLogix module?

  The 1756-TBCH is compatible with most 36-pin ControlLogix I/O modules. However, some modules with larger wire requirements may necessitate the 1756-TBNH (depth-extended) version. Always check the specific module’s installation manual for the recommended RTB model.

• Is the 1756-TBCH suitable for outdoor use?

  This terminal block is designed for use in clean, dry industrial environments with an IP20 rating. For outdoor or corrosive applications, it must be installed within a properly rated NEMA or IP-certified enclosure.

• What is the benefit of the cage clamp over the screw clamp?

  Cage clamps provide a faster, more reliable connection that is less prone to “backing out” due to vibration. They are often preferred in heavy industrial machinery where mechanical movement is constant.

• Can I replace a module while the system is powered?

  While the RTB supports Removal and Insertion Under Power (RIUP) when paired with compatible ControlLogix modules, you must follow all facility-specific safety protocols and ensure that the surrounding atmosphere is non-hazardous before performing an insertion or removal.