ABB CTI 21 Temperature Input Module

Overview

The CTI 21 (formerly 3BSE002176R1) is a compact, high-performance temperature input module designed for use with ABB's S800 I/O stations and AC800M controllers. It supports a wide variety of temperature sensors, eliminating the need for external signal conditioners. Each channel is individually configurable for sensor type and measurement range, offering flexibility for multi-point temperature monitoring.

Key Features

• Channel Count: 8 differential inputs, galvanically isolated in groups.

• Sensor Types: RTDs (Pt100, Pt1000, Ni100, Cu10) and thermocouples (B, E, J, K, N, R, S, T).

• Resolution: 16-bit A/D converter, 0.1°C resolution typical.

• Accuracy: ±0.1% of span for RTDs, ±0.2% for thermocouples (excluding sensor error).

• Cold-Junction Compensation: Internal or external via CJC sensor on termination module.

• Wire-Break Detection: Automatic detection for RTDs and thermocouples; configurable response.

• Update Time: 100 ms for all channels (filter dependent).

• Configuration: Per channel via software (Control Builder) for sensor type, range, and filtering.

Technical Specifications

• Input Impedance: >10 MΩ (voltage mode), current source for RTDs.

• Common Mode Rejection: >120 dB at 50/60 Hz.

• Isolation Voltage: 500 V AC channel-to-channel and channel-to-ground.

• Power Consumption: 80 mA @ 5 V DC (from backplane).

• Operating Temperature: -25°C to +70°C.

• Dimensions: 12.5 mm wide module, 119 x 102 x 72 mm (H x W x D).

Functional Description

The CTI 21 converts analog temperature signals to digital values using a high-resolution sigma-delta converter. Linearization and scaling are performed automatically based on the selected sensor type. For thermocouples, the module can use an external CJC sensor mounted on the termination unit, or an internal reference. The module also provides sensor diagnostics: open-circuit detection forces the output to a predefined value (upscale/downscale) or generates an alarm.

Wiring and Termination

The module connects to field wiring via a separate termination unit (TU) such as TU810 or TU830. These TUs provide screw or spring-clamp terminals, and include cold-junction sensors for thermocouple applications. The module and TU are mechanically keyed to prevent mismatching. Wiring is simple: for RTDs, use 3- or 4-wire connections to cancel lead resistance; for thermocouples, use appropriate extension wire.

Applications

• Heat treatment furnaces (temperature profiling).

• HVAC systems (zone temperature monitoring).

• Chemical reactors (exothermic reaction control).

• Food processing (pasteurization, sterilization).

• Power plants (bearing temperatures, exhaust gas).

Configuration and Diagnostics

Using ABB's Control Builder, each channel can be assigned a sensor type, engineering units, alarm limits, and filter time constant. The module supports simulation mode for testing. Front LEDs indicate module status and channel faults. Detailed diagnostics are available via the fieldbus, including open-circuit, over-range, and under-range conditions.

Note: This document provides technical data. Always consult the S800 I/O user manual for installation and safety guidelines.