7B32 Isolated, Process Current Input

The 7B32 is a single-channel signal conditioning module that interfaces, amplifies and filters a process-current input and provides a protected precision output voltage of either +1 V to +5 V or 0 V to +10 V. Process-current input signals are measured by reading the voltage across an internal 200 Ω protected resistor. Model 7B32 features a nonlinearity of ±0.02% maximum and an accuracy of ±0.1% maximum (±0.01% typical). To accurately measure low level signals in electrically noisy environments, 1500 V rms of galvanic transformer-based isolation with a common mode rejection (CMR) of 105 dB @ 50/60 Hz is provided. Rated to operate with a nominal +24 V DC supply, Model 7B32 is mix-and-match and hot-swappable with other 7B Series input modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power.

Inside the 7B32 Series Module

The floating current input of Model 7B32 is fully protected up to 120 V rms line voltage. A one-pole 100 Hz filter preconditions the voltage signal across the 200 Ω protected input resistor prior to amplification by a low drift amplifier. Amplitude modulation is used to implement transformer isolation (1500 V rms input-to-output and power). Isolated front-end circuitry power is supplied by a DC/DC converter. The output section contains a two-pole low pass filter (-3 dB @100 Hz), a buffer amplifier and a power oscillator. The two-pole output filter and subsequent buffer ensures that a low noise, low impedance (<1 Ω) signal is available at the output to drive loads to 2 kΩ minimum.