1746-INT4 | Allen-Bradley Isolated Thermalcouple/mV Analog Input Module

The 1746-INT4 SLC 500 Thermocouple/mV Isolated Input Module by Allen-Bradley is an SLC 500 module which stores digitally-converted thermocouple and analog millivolt (mV) data for future retrieval by any SLC 500 processor. It has Four (4) input channels for Thermocouple and mV sensors. It has a backplane current of 110 mA at 5V DC and 85mA at 24V DC and an overall backplane power rating of 0.6W. It has Four (4) individually isolated input channels that are also isolated from the backplane and it uses a Sigma-Delta ADC modulation conversion method. It uses an analog filter with a low pass digital filter and has a normal rejection mode greater than 60 dB at 60 Hz between terminals. It also has a common rejection mode greater than 120dB between the inputs and chassis ground with 1kΩ imbalance and has an 8Hz channel bandwidth. The 1746-INT4 requires field calibration and must be calibrated at least once every year.

It provides isolation tested at 1000V transient or 150V AC between channel-to-channel and channel-to-backplane. It has 5 LED indicators with 4 indicating each channel status and one indicating the module’s status. It has selectable B, C, D, E, J, K, N, R, S, and T thermocouple input types, and 50-50 mV DC and 100-100 mV DC analog inputs. It has an input impedance greater than 10 Mega Ohms and offers a 20nA open-circuit detection, with a circuit detection time of 5ms. It has a step response time of 600ms in the worst circuit case, and the module has an overall accuracy that is input-type dependent. Its operating temperature ranges from 0-60 deg. Celsius (32-140 deg. Fahrenheit) at 5-95% non-condensing humidity and is CE, CSA, and UL-certified.

The Allen-Bradley 1746-INT4 is a Four (4) channel Thermocouple / mV analog input module. This module is used for SLC 500 Programmable Logic Controller (PLC) platform. This module is compatible with Thermocouple sensors Type C, D, J, K, T, E, R, S, B, and N. It may also be used with mV signal with range of -100 to 100 mV DC.

This module may be used in applications with Temperature range of -270 to 1820 Deg. Celsius. Each Thermocouple has specific different range that is within the absolute range. Additionally, operable mV signal voltage are -50 to 50 mV and -100 to 100 mV which typically comes from signal transducers. This module follows Thermocouple linearization of IPTS–68 standard, NBS MN–125 and NBS MN–161. It also has Cold Junction Compensation terminal that enables accuracy of Accuracy ±1.5 °C (34.7 °F), 0 … 70 °C (32…158 °F). It has a user selectable Temperature scale of °C or °F and 0.1 °C or 0.1 °F and millivolt scale of 0.1 mV or 0.01 mV.

For safe operation, the module is also equipped with open-circuit detection. When open circuit is detected to any of the module’s channel, Temperature indication may display the maximum upscale and downscale value or Zero (0) value. This allows quick and visual evaluation of the quality of input signal received by the module which may be used by any Human Machine Interface (HMI) or Supervisory Control and Data Acquisition (SCADA) system as reference for a faulted input.