3B47

Interfaces, amplifies, filters, isolates, & linearizes analog input voltages from a J, K, T, E, R, S or B-type thermocouple Thermocouple input signal is internally linearized High accuracy internal cold junction compensation. Module provides +1500 V peak of galvanic transformerbased isolation with a common mode rejection (CMR) of 160 dB @ 50/60 Hz and a normal mode rejection (NMR) of 60 dB @ 50/60 Hz. All 3B47 series modules are mix-and-match and Hot Swappable.

Industrial signal conditioning Industrial signal isolation Industrial signal filtering

The 3B47 is a single-channel isolated thermocouple signalconditioning module which interfaces, amplifies, isolates, protects, linearizes and filters analog input voltages from a J, K, T, E, R, S or B-type thermocouple. The thermocouple input signal is internally linearized to provide an output voltage which is linear with temperature, High accuracy internal cold junction compensation and a predictable upscale open circuit indication provide a complete signal conditioning solution. To accurately measure low level signals in electrically noisy environments, +1500 V peak of galvanic transformer-based isolation with a common mode rejection (CMR) of 160 dB @ 50/60 Hz and a normal mode rejection (NMR) of 60 dB @ 50/60 Hz are provided. This plug-in, mix-and-match, hot-swappable module is easily field calibrated via front-panel zero and span adjustments.

A chopper-stabilized low-drift input amplifier assures stable long-term stability. At the amplifier input, a zero-scale input voltage is subtracted from the input signal to set the zero-scale value. For user convenience, the zero and span optionally can be factory configured to meet custom needs (Model 3B37- CUSTOM). Zero suppression can exceed 100% of the input range. This enables suppression of a zero-scale input value many times larger than the total span for precise expandedscale measurements of a selection portion of an input signal. The differential input circuit on the field side is fully floating, eliminating the need for any input grounding. Signal isolation by transformer coupling uses a proprietary modulation technique for linear, stable and reliable performance. A demodulator on the computer side of the signal transformer recovers the original signal which is then filtered and buffered to provide a low-noise, low impedance output voltage.

Internal cold-junction compensation largely corrects errors arising from parasitic thermocouples formed by thermocouple connection to the input screw terminals, providing an accuracy of +0.5oC over the +5oC to +45oC ambient temperature range. The module generates a predictable upscale signal to indicate an open thermocouple; for a downscale response, connect a 47
M, 0.25 Watt resistor across screw terminals 2 and 4 on the 3B Series backplane.