The Bently Nevada 3500/61 Temperature Monitor is a 6-channel module within the 3500 Series machinery protection system, designed for accurate and reliable temperature monitoring . It accepts inputs from both Resistance Temperature Detectors (RTD) and Thermocouples (TC), conditioning these signals and comparing them against user-programmable alarm setpoints to protect critical rotating machinery . The 3500/61 variant includes recorder outputs for each of its six channels .

Configuration is performed using the 3500 Rack Configuration Software, allowing users to program each module for either RTD or TC measurements . Different I/O module options provide flexibility: the RTD/TC non-isolated version can accept a mix of RTD and TC inputs, while the TC isolated version provides 250 Vdc of channel-to-channel isolation to protect against external electrical interference and ground loops . The module features high input impedance, greater than 10 MΩ for each lead .

For applications requiring the highest level of availability, such as in Triple Modular Redundant (TMR) configurations, three temperature monitors are installed adjacently. In this setup, the system employs voting logic to ensure accurate operation and prevent single-point failures . The 3500/61 is certified for use in safety-related applications up to SIL 2 , consuming 9 watts of power and operating reliably within an ambient temperature range of -30 to 65°C .