The Seametrics AO55 is a blind (non-indicating) 4-20 mA transmitter, designed for use with almost all Seametrics fow sensors. It accepts a pulse frequency input from the fow sensor, and converts this input into a continuous analog output signal. Power for the transmitter is taken from the current loop itself, so only two wires are required. The digital design makes it possible to span the unit in the feld without tools. The frequency at which 20 mA is desired is entered on a set of rotary switches, and an internal microcontroller automatically scales all other values accordingly. An additional beneft of the microcontroller is its ability to average inputs, for smoothing of the output signal. The degree of averaging can be selected in the feld, from 2 to 16 seconds. For maximum environmental protection, the electronic components are encased in a special semi-fexible urethanepotting material. The housing is cast from aluminum and fuse-coated. The clamshell housing is connected directly to the fow sensor or, in the wall mount version, provided with mounting feet. The AO55 will operate on a relatively wide range of current loop voltages, 24 to 36 Vdc. Lower voltages limit the load that can be applied to the loop without distortion of the signal. (See Load/Supply chart if there is a question regarding voltage vs. load.) A built-in power regulator supplies the appropriate power to the fow sensor. Typical applications for this transmitter are telemetry (or SCADA), distributed control systems, programmable controllers, data logging, and chart recording. APPLICATIONS • Telemetry/SCADA • Distributed control systems • Programmable controllers • Chart recording • Data logging FEATURES • Pulse-to-analog converter • Current loop powered • Smooth output signal • Easy set-up • Durable