Hydrologic

LEVEL

measuring of water elevation in rivers, reservoirs, and ground water

LPN 8/1 · 4-20 mA LEVELMETER


  • Level and gradient monitoring.
  • Self-cleaning "bubble to bubble".
  • 4-20 mA output.
  • Alarm thresholds.
  • Gray or BCD output via ISP 8.
  • High accuracy and stability..
  • No electronics underwater.
Functions
  Using a built-in compact air generator, LPN 8/1 injects a small air flow through a pressure pick-up (BUBBLE TO BUBBLE).

This air pressure is applied to a SILICON MEMBRANE SENSOR which gives an electrical signal in proportion to the water level upstream from spillway or contraction.

In order to improve result accuracy and credibility, LPN 8/1 takes into account the following effects :

  • Temperature of pressure sensor.
  • Supply voltage.
  • Pressure in air reserve tank.

These signals are digitized and used by a MICROPROCESSOR which has the following functions :

  • Acquisition of digitized measurements.
  • Digital processing of measurements :
    • filtering,
    • compensation of temperature drifts,
    • compensation of interval drifts,
    • scaling.
  • Generation of an analogue signal in proportion to the level.
  • Level monitoring with regard to the thresholds.
  • Compressor control to maintain a continuous air flow.
  • Monitoring normal internal operating conditions (temperature, voltage, pressure) with an alarm facility.
  • Control of display unit and keybord for local operator dialogue.
  • Control of the asynchronous serial port communication V 24 / RS 232 C.
  • Control of the pneumatic circuit AUTOMATIC PURGING.

LPN 8/1 is housed in a compact DIN 144 mm box and can be supplied in a wall cabinet.

Technical
specifications
 
Measurement range
Single built-in comp.
 0 - 5 m or 0 - 10 m.
External compressor
 20 m to 60 m.
Resolution 10 000 points.
Total error at 20°C
Screen reading
 ±0,1% FS of sensor.
On analogue output
 ±0,2% FS of sensor.
Temperature drift ±0,2% FS of sensor.
between -20°C / +60°
Measurement rate 4 measurements / sec.
Analogue output (not insulated)
Current
 4-20 mA (R < 500 ohms)
Voltage
 0-10 V (R > 100 k ohms)
Serial link V 24 / RS 232 C.
Relay output 0.2 A / 220 VAC
(volt free contact).
Power supply 24 V DC/AC (19.2 to 28.8 V).
12 V DC/AC on request.
Consumption
Average
(without relay or A.O.)
 20 mA
Maximum (peak)
 350 mA (10 m range).
Temperature range -20°C to +60°C.
Relative humidity < 80% without condensation.
Operator dialogue
Display
 16 Alphanumerical characters.
Keyboard
 4 keys.
Box DIN 144 to embed.
Size
 144 x 144 x 165 mm.
Weight
 2.5 kg.
Degree of protection
 IP 545.
Purging Automatic.
Parallel Gray /
BCD output
 

ISP 8 specifications
Size 120 x 180 x 40 mm.
Outputs
  • Open collector transistor.
  • Volt-free contact.
    •
    Power supply
    Open collector
    		 Through LPN 8.
    Relay output
    		 12 VDC.

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