7B30

Rev. 0 | Page 2 of 8

GENERAL DESCRIPTION

The 7B30 is a single-channel signal conditioning module that

interfaces, amplifies and filters unipolar and bipolar milli-vilt

and voltage inputs and provides a protected precision output of

either +1 V to +5 V or 0V to +10 V.

To measure a process current input, a plug-in 250W current

sensing resistor, Model AC1391, may be installed directly on the

7B backplane, using available pin sockets. The external current

sense resistor allows the current loop to be maintained even

when the module is removed from the backplane. Model 7B30

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 160 dB @ 50/60 Hz and a normal mode

rejection (NMR) of 60 dB @ 50/60 Hz are provided. Rated to

operate with a nominal +24 VDC supply, Model 7B30 is nix-

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.

The floating differential input of Model 7B30 is fully protected

up to 120 V rms line voltage. A one-pole 3 Hz filter

preconditions the input signal prior to amplification by a low

drift input amplifier. Amplitude modulation is used to

implement transformer isolation (1500 V rms input-t-output

and power). Isolated front-end circuitry power is supplied by a

DC/DC converter. The output section contains a two-pole

output filter and subsequent buffer ensures that a low noise, low

impedance (<1Ω) signal is available at the output to drive loads

of 2 kΩ minimum.

Figure 2