Princo's Models L2631 and L2631R are multi-featured, high technology, RF impedance
sensing, continuous level transmitters. They use the same two wires to receive their operating
power and transmit their output signals. Used in conjunction with Princo L100 Series probes, the
units monitor level as sensed along the length of the probe and put out a 4 to 20 mA signal
which is directly proportional to this level. Null-KoteTM circuitry permits operation in virtually any
process material, regardless of its dielectric, conductivity, viscosity or build-up.
The 4 to 20 mA output signal may be transmitted over a distance of 2000 feet to a remote
meter, controller, recorder, etc., using almost any unregulated 24 Vdc power supply. Intrinsically
safe operation may be achieved through the use of a 24 Vdc regulated power supply and Princo
Model S939 Intrinsic Safety Barriers.
The L2631/L2631R is capable of "driving" any current sensing, 4 to 20 mA device with an input
impedance of 500 ohms or less.
The highly accurate and stable output of the L2631/L2631R is maintained over the wide ambient
temperature ranges commonly found in many outdoors applications.
Self-diagnostic circuits give an immediate indication of many application or installation related
problems such as breaches or pinholes in the probe sheath or moisture in the electronic
housing. Probe connections are made reliably and automatically when the probe is screwed into
the electronic housing.
Other significant features include power supply polarity reversal protection and use of state-ofthe-art integrated circuits