Product Summary
The Allen-Bradley 1746-NT8 is an SLC 500 Thermocouple/mV Analog Input Module. It provides eight high-resolution channels for precise temperature measurement. This module converts analog signals from J, K, T, E, S, R, B, and N thermocouples. It also accepts ±50 mV and ±100 mV inputs. The module uses sigma-delta modulation for reliable digital conversion. It is a critical component for any SLC 500 control system.
Expert Technical Evaluation & Performance Review
The 1746-NT8 delivers exceptional signal integrity for demanding industrial processes. It uses a sigma-delta A/D conversion method with 16-bit resolution. This ensures highly accurate temperature readings from your thermocouples. The module offers a step response of 60 milliseconds for input signals. This provides fast reaction to temperature changes in your system.
The module includes a digital low-pass filter with selectable frequencies. This filter effectively rejects electrical noise from the environment. It achieves a normal mode rejection greater than 100 dB at 50-60 Hz. The common mode rejection between inputs and ground also exceeds 100 dB. This performance guarantees stable readings even in noisy factory settings.
The module automatically calibrates itself every two minutes after power-up. This self-calibration maintains accuracy without any operator intervention. It offers input overvoltage protection at ±30V DC and 600W pulsed. This protects the module from accidental voltage spikes during wiring. The circuit isolation is tested at 500V DC for one minute. This ensures safe operation between inputs, chassis ground, and the backplane.
Two cold-junction compensation (CJC) sensors come with the terminal block. They provide an accuracy of ±1.72 degrees Celsius for thermocouple measurements. The overall input impedance is greater than 10 M Ohms. This high impedance prevents signal loading on your sensors. For full accuracy, connected devices must have an impedance under 100 Ohms. This module is UL and CUL-approved for reliable industrial use.
Step-by-Step Installation Guide
First, ensure your SLC 500 system is powered down completely. The 1746-NT8 can be installed in any I/O chassis slot except Slot 0. Slot 0 is reserved for the power supply or processor module. For a fixed style controller, use a 1746-A2 chassis. For modular controllers, simply slide the module into the desired slot.
Next, connect the 1746-RT34 removable terminal block (RTB) to the module. The RTB includes the two CJC sensors for thermocouple wiring. Wire your thermocouple or millivolt sensors to the appropriate terminals. Ensure the sensor impedance is less than 100 Ohms for best accuracy. The module supports open-circuit detection with selectable upscale, downscale, or zero settings.
Finally, power up the SLC 500 system and check the module status. The 1746-NT8 has nine green LED lights for status indication. These LEDs show the operational status of each channel and the module. Configure the input type and filter settings in your control program. The module is compatible with SLC 5/01, 5/02, 5/03, 5/04, and 5/05 processors.
Logistics & Standard Packaging Details
- One Allen-Bradley 1746-NT8 Thermocouple/mV Analog Input Module
- One 1746-RT34 Removable Terminal Block (RTB)
- Two Cold-Junction Compensation (CJC) sensors installed on the RTB
- The module is tested and verified for full functionality
- We offer express shipping via FedEx, UPS, and DHL for fast delivery
