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RF Addmittance type level switch

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Product Description

An admittance based level switch with RF signal transmission between probe and evaluation unit via a co-axial cable with drain wire having driven shield arrangement to eliminate cable capacitance and drift due to change of cable capacitance with temperature. You can install the evaluation unit even far from the probe. The calibration controls are available in the evaluation unit. A special ten LED dot display/bar display simplifies calibration and indicates material trend in vicinity of the point level.

 

This switch can be efficiently used to reduce the inventory as the same evaluation unit can be field configured either for High or Low level fail-safe detection. This switches Ignores build-up of service material between probe, the vessel walls and the coating. The level limit switch uses 3-Electrode technique with driven shield arrangement to achieve high degree of immunity.

 

The measuring system for this level limit detection tool consists of an evaluation unit and an immune-coat probe that could be mounted either from the top or side of the vessel. The probe comprises sense and shield electrodes electrically isolated from the metallic tank by means of suitable insulators. The sense electrode of the switch and the vessel wall serve as the two electrodes of a capacitor with the service material as the dielectric. A change in material level causes a change in dielectric, which in turn causes a change in admittance of this tank capacitor.

 

The processed signal is used to energize or de-energize a relay whose output contacts are available for annunciation or control.

 

An accurate measurement of this change affords an indirect measure of the level of material in the tank. The evaluation unit measures the change of admittance accurately by using radio frequency (R.F.) technique coupled with coat immunizing circuitry.

 

Many process industries viz. cement, power, steel, food, chemicals, fertilizer, sugar, detergent etc. have been using these switches for reliably measuring and self checking the level of service material which may include fine or coarse solids of low dielectric constant that have a tendency to stick.

 

A wide variety of probes with different mounting connections is available to suit various applications. We offer specially designed ceramic insulated rod / rope probe suitable for operating temperatures up to 600° C max.

 

Note : Bar display is recommended for longer distance between probe and evaluation unit and for materials having tendency to absorb moisture.

 

TECHNICAL DATA

Evaluation Unit

HousingCast Aluminum, weather proof, back panel / wall mounting.
Cable Entries3 No. / 2 No.
Max. Amb. Temp.-20º C to + 60º C.
Power Consumption5 VA approx.
Mains Voltage230 V or 110 V AC (-15% to +10%), 50 Hz; 24 V AC/DC 90 to 260 V AC universal power supply (to be specified while ordering).
Relay OutputOne/two set (s) of potential free change over contacts rated at 230V AC 6A, 50 Hz for non-inductive loads.
Fail-Safe ModeMax. or Min. field selectable.
Indication (switching)Red LED for alarm, Green LED for normal.
Indication (sensitivity)10 step LED dot / bar display
Response Time0.2 second typical.
Switching DelayAdjustable from 0.5 to 20 second for probe covered or uncovered.
Connection to ProbeVia co-axial screened cable with drain wire.
Switching Hysteresis0.2 pF. typical.

Probe

A wide variety of probes with different mounting connections is available to suit various applications. We offer specially designed ceramic insulated rod / rope probe suitable for operating temperatures up to 6000 C max.