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L3541 Remote RF Controller
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PRINCO’s L3541 level controller gives you the optimum combination of reliability, sensitivity, features, and cost.

Conformally coated electronics, NULL-KOTE™ circuitry, explosion-proof / weatherproof enclosures, ROLLOCK™

probe construction and our unique 10 Year Warranty mean the ultimate in reliability. Excellent sensitivity, coupled with stability of 1 picofarad over the entire operating range, gives you a true set and forget installation. L3541

controllers are used with NULL-KOTE™ probes, available in a wide variety of lengths and designs to fit every application.

Princo, one of the pioneers of RF level sensing technology, has provided accurate, dependable, long lived service

for thousands of applications in all types of industries, worldwide for more than 4 decades.




•          Water-based liquids


          Hydrocarbons and solvents

          Powders and granulars









•  Remote Sensor Mounting – Eliminates the need to work in high places, hazardous locations, or inclem- ent weather. Control unit can be up to 3000 feet from sensor and used ordinary twisted pair cable.

•  Universal – Wide range of point level applications. Detects the level of powders, granules, conductive or non-conductive liquids … even the sticky ones.

•  NULL-KOTE™ Circuitry – Negates effects of coating build-up.

•  High Sensitivity and Temperature Stability – For critical low response applications.

•  Designed to Survive – RF immune, vibration-proof, all circuit boards are conformally coated (tropical- ized) for extra protection.

•  Easy-On Probe Connection – Automatically provides simple, fast installation and reliable operation without wires, connectors, or terminal strips. Simply screw probe into the housing.

•  Unique Status Indicator – Red / green LED shows presence or absence of material and also indicates power on

•  Heavy Duty Relay – 2 sets of form C contacts rated at 5A, 115 Vac resistive contacts

•  High or Low Fail-Safe  Field selectable.

 Wide Temperature Range – Standard process temperature: -300 to 500°F (-184 to 260°C).

•  ROLLOCK™ PROBES – No part of the probe can fall into the process or be blown from the mounting. No re-tightening of seals required.

 Time-Delay – 0 to 30 second delay minimizes relay chatter.

 Ten-Year Warranty – The only level instruments available with this unique assurance of quality.


L3541 Specifications

TYPE: Point type (remote sensor, on/off), solid state electronic, RF impedance-sensing, level controller. 

POWER REQUIREMENTS: 95 to 135 Vac, 50 to 60Hz or 205 to 250 Vac, 1.3 watts; or 12/34 Vdc, <1 Watt.

AMBIENT TEMPERATURE: -40 to 150 °F (-40 to 66 °C).

SENSITIVITY: Senses capacitance as low as 0.15pF.  May be decreased to approximately 1000pF.

TEMPERATURE STABILITY: Senses capacitance as low as 0.15pF.  May be decreased to approximately 1000pF.

ALARM TYPE: Selectable as either High Acting or Low Acting.

ALARM  ACTION: Fail Safe Alarm : Control relay de-energizes (drops out) upon alarm.

CONTROL RELAY CONTACTS: Two sets of form C contacts, rated at 5 amperes, 115 Vac or 26 Vdc, resistive load.

TIME DELAY: Adjustable from 0 to 30 seconds. Standard mode is delay alarm both on and off. Consult the factory for optional times and modes.


DEAD BAND: Adjustable over range of 1.3pF for low values of process capacitance.  Adjustment range increases up to approximately 1000pF, for high values of process capacitance.


SELF TEST: Pushbutton tests control relays and any devices driven through them.

ELECTRONIC HOUSINGS: Control Unit: Structural foam, thermoplastic molded base & hinged cover, NEMA 4X.

                                      Sensor Head: Heavy duty, explosion-proof, cast aluminum.