Section One
Description
1-1
A. General Description
The Princo Model L2000 is a low-cost, adjustable, RF Impedance point level controller. It may
be used, in conjunction with any Princo L840 Series Sensor Probe, to detect the presence or
absence of process material within a storage vessel.
The basic instrument consists of an electronic chassis within a heavy-duty, cast aluminum,
weatherproof, explosion-proof housing. The housing has a removable lid which exposes the
electronic chassis. The chassis is composed of two circular printed circuit boards which are held
together by a removable system of mechanical spacers and electrical interconnects. The
chassis is easily removed from the instrument housing, allowing convenient replacement,
should troubleshooting be required.
The housing, with internal electronic chassis, attaches directly to any one of the Princo L840
Series point level probes. An electrical and mechanical probe connection is made by simply
screwing the housing directly onto the probe upper hub NPT fitting. The probe lower hub NPT
fitting threads directly into the storage vessel, thus allowing probe entry into the vessel, as well
as, mechanically and electrically fixturing the electronic housing and probe to the vessel
construction.
The electronic chassis performs the RF impedance measurement, and compares the
measurement with a set-point established by the coarse and fine sensitivity adjustments on the
top of the chassis. The set-point adjustment is established by making adjustments with actual
presence and absence of process material in the storage vessel. When the vessel's condition
changes relative to the set-point, two control relays are switched and the Probe Status LED
changes state.
B. Functional Description
The basic function of the device is to detect the presence or absence of process material within
a storage tank or holding vessel, and to announce the process material detection in the form of
an “alarmed” set of relay contacts.
The Model L2000, used in conjunction with an L840 Series Sensor Probe, can detect the
presence or absence of a wide variety of process materials, from electrical insulators with low
dielectric constants, to highly conductive electrical conductors. The mechanical nature of these
materials can range from dry powders or granulars, to liquid materials with virtually any
consistency -even thick, viscous materials that severely coat the sensor probe.
1. Basic Features
•RF Impedance Sensing Measurement Technology with Null-KoteTM
The L2000 uses RF impedance technology proven in tens of thousands of applications. The
principle of operation is very simple: an L840 Series Sensor Probe is mounted in the storage
vessel. As the process material changes from not contacting the probe to contacting the
probe, a corresponding change in electrical impedance occurs between the probe and the
metal storage vessel wall. (For non-metallic storage vessels, a "dual element" probe is
used. In this case, the impedance change occurs between the "active" and "ground"
elements of the probe.)
The highly sensitive impedance measurement circuits inside the L2000 detect and measure
this impedance change by means of a low level, radio frequency current that flows from the
