Description

ABB TU891 Module Termination Unit

Configured for field signal and process power connections, the ABB TU891 3BSC840157R1 (TU891 Module Termination Unit) provides the terminal interface between field wiring and the associated I/O hardware. It provides 8 channels, 27 gray process terminals, and a nominal 24 V connection arrangement.

Hardware Specifications

Parameter	Specification
Model	TU891
Full Model	TU891 3BSC840157R1
Spare Model	3BSC840157R1
Brand	ABB
Product Type	Module Termination Unit
Type	Compact
Channels	8
Connection	Terminal block
Process Connections	27 gray terminals
Voltage	24 V
Maximum Current per I/O Channel	2 A
Dielectric Test Voltage	500 V AC
Mounting	Horizontal
Origin	Sweden
Weight	0.2 kg
Dimensions	Estimated shipping size: 7.6 x 7.6 x 20.3 cm
Tariff Code	8537101190

ABB Industrial I/O Interface Characteristics

The TU891 provides a compact terminal interface for 8 field channels. Its 27 gray terminals accommodate field signal and process power connections, while the terminal-block construction provides direct physical access for field wiring.

The specified 2 A maximum current per I/O channel defines the stated channel current limit. In addition, the 500 V AC dielectric test voltage specifies the electrical withstand test level provided in the supplied data.

The horizontal mounting orientation determines the physical installation position. Therefore, installers should maintain adequate clearance around the terminal area for conductor routing and terminal access.

Frequently Asked Questions

Q: How many I/O channels does the TU891 provide?

A: The TU891 provides 8 channels.

Q: What is the maximum specified current per I/O channel?

A: The specified maximum current is 2 A per I/O channel.

Q: What terminal arrangement does the TU891 use?

A: The supplied data specifies a terminal-block connection with 27 gray process terminals.

Field Installation Guidelines

1. Mount the TU891 in the specified horizontal orientation and secure it according to the applicable cabinet or mounting-system requirements.
2. Route field conductors so that terminal access remains unobstructed during inspection and maintenance.
3. Separate signal wiring from high-current or high-noise conductors where the installation environment requires electromagnetic interference control.
4. Terminate cable shields according to the grounding architecture specified for the installed control system. Do not assume a shield termination method that is not defined by the system documentation.
5. Verify conductor polarity, terminal assignment, and channel allocation against the applicable wiring diagram before energization.
6. Keep the specified 2 A maximum current per I/O channel within the connected circuit design.
7. Inspect terminal tightness and conductor seating before commissioning.
8. Verify electrical isolation requirements using the applicable system-level installation documentation; the supplied TU891 data specifies a 500 V AC dielectric test voltage but does not define a field insulation-testing procedure.

Specifications

• Brand: ABB

Advantages

• High reliability in industrial environments
• Supports continuous operation
• Compatible with major PLC/DCS systems