The Seametrics AO55 blind analog transmitter is a non-indicating 4-20 mA transmitter designed for use
with almost all Seametrics flow sensors. The AO55 accepts a pulse
frequency input from the flow sensor and converts this input into a continuous analog output signal.
Power for the AO55 is taken from the current loop itself so only two
wires are required.
The digital design of the Seametrics AO55 blind analog transmitter makes it possible to span the unit in
the field without tools. The frequency at which 20mA is desired is entered on a set of rotary switches,
and an internal microcontroller automatically scales all other values accordingly. An additional benefit of
the AO55 is its ability to average inputs for smoothing of the output
signal. The degree of averaging can be selected in the field, from 2 to 16 seconds.
For maximum environmental protection, the electronic components of the AO55
transmitter are encased in a special semi-flexible urethane potting material. The housing is cast from
aluminum and fuse-coated. The AO55's clamshell housing is connected
directly to the flow sensor or, in the wall mount version, provided with mounting feet.
The AO55 will operate on a relatively wide range of current loop voltages,
12 to 36 VDC. However, lower voltages limit the load that can be applied to the loop without distortion of the
signal. A built-in power regulator supplies the appropriate power to the flow sensor. Typical applications for
the AO55 are telemetry (or SCADA), distributed control systems,
programmable controllers, data logging, and chart recording.
For replacement AO55 electronics, use the
Seametrics AO55 Replacement Module. This module contains the same electronics and display found in AO55 transmitter
but in a package that makes replacement simpler.
