American Magnetics 188CPS Point-Sensing Instrument - Manual (Page 2)

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Introduction
The American Magnetics, Inc. (AMI) Model 188CPS Point Sensing Instrument
system is a microprocessor-based solution designed to provide sensing for up to five
(5) points for virtually any non-conducting liquid.
Capacitance-based point sensing
The system consists of a Model 188CPS Point Sensing Instrument, plate sensors, and
connecting cables. The instrument sensing elements are typically parallel plate
capacitors which are mounted on a stainless steel support tube. The plate capacitors
allow a non-conducting liquid (or other material) to become the dielectric between the
plates. The instrument measures the plate capacitance which is directly related to the
percentage of the plate immersed in the non-conducting liquid.
The plate sensors are normally constructed in diameters of 3.5" to 5", however, custom
designs which require smaller diameter tank penetrations can be provided for specific
needs. Up to five plate sensors can be monitored by a single Model 188CPS
instrument. The support tube may also function as a cylindrical capacitor which may
be used for continuous level measurement using a separate AMI level instrument.
Simple operation
The instrument is equipped with five tri-color LED’s which provide positive
indication of immersed or exposed state for each point, as well as providing fault
indications. No user input is required for normal operation of the instrument.
Remote monitoring
The Model 188CPS provides five relay contact pairs available through a terminal
block located on the rear panel. When a plate sensor is immersed in the non-
conducting liquid, the respective relay contact pair closes.