PD940 DIPSTICK

Level, conductivity and temperature transmitter, Analogue current output: 4-20 mA, Digital I/O, P-NET via RS485

• Compact sanitary design – designed for the food industry
• Level, conductivity and temperature sensor in a single unit
• Handles foam in liquid – only the equivalent liquid of the foam is included
• Reliable continuous level measurement
• Designed for top mounting in vessel
• Flexible configurations to suit your specific application
• Conductivity sensor
• Temperature sensor, process temperature range 0 °C to 100 °C
• Analogue current output: 4-20 mA
• Digital I/O
• Programmable in COPP
• P-NET via RS485

Part. No.	Name	Price	Quantity
900067	PD940 DIPSTICK 380mm	kr. 10,675.00	PD940 DIPSTICK 380mm quantity
900118	PD940 DIPSTICK 700mm	kr. 10,675.00	PD940 DIPSTICK 700mm quantity
900293	PD940 DIPSTICK custom length	kr. 11,185.00	PD940 DIPSTICK custom length quantity

Product Description

Compact sanitary design – designed for the food industry
Level, conductivity and temperature sensor in a single unit.
Handles foam in liquid – only the equivalient liquid of the foam is counted
Reliable continuous level measurement
Designed for top mounting in vessel
Flexible configurations to suit your specific application
Conductivity sensor
Temperature sensor, process temperature range 0 °C to 100 °C
Analogue current output: 4-20 mA
Digital I/O
Programmable in COPP
P-NET via RS485

APPLICATION

The PD 940 Dipstick is a hygienic electronic level, conductivity and temperature sensor for electrically conductive liquids in a metal tank. A special flange welded onto the tank provides for easy clamp mounting of the Dipstick.

The Dipstick has a hygienic and robust design suitable for food industry and performs very fast measurements making it ideal for inline process control.

Level measurement is independent of conductivity and works with different liquids without any calibration.
Foam on top of liquids, like in a milk air eliminator, contributes to level with the equivalent liquid content in the foam.
Level output is measured in meters starting from the isolation between the tip and stick.

Conductivity measurement is level independent and is factory calibrated with a cell constant that fits most applications. It is useful to detect water, milk or CIP liquids in the tank without further calibration.
For precise conductivity measurement, it is possible to adjust the cell constant according to the actual tank diameter or to conductivity measured with a reference instrument.
The module also includes an analog source output (4-20 mA) and a Digital I/O that can source 1 A to ground.
The Dipstick is programmable in COPP, which means that part of or all of an automation application can run in the Dipstick. The program can make use of ready-made components to control and monitor any process or machine application, locally in the Dipstick as well as via the network, interacting with other devices.

PROGRAMMING EXAMPLES
Analogue output current (4-20 mA) can indicate actual level or conductivity.
The cabled P-NET RS485 interface can communicate all the measured variables in the module.
The digital output can control for example a pump depending on the measured level.
A program can convert level to volume using a strapping table to fit irregular tank shapes.

Measurement principles:
• The isolated tip part measures resistance to tank.
It is converted to conductance and scaled with the cell constant to show specific conductivity for the liquid
• The stick part measures resistance to tank. Level is calculated as the ratio between stick and tip resistance scaled with the tip length.
• The accurate Pt1000 sensor in the tip use a speed up algorithm to calculate the final tip temperature in advance.

Accurate and reliable measurement conditions:
• The tip is always completely covered with liquid
• Measurements assume constant vertical tank area (e.g. a cylinder)
• Liquid conductance is within specified limits for the module
• Tank, stick and tip is clean and without isolating layers
• Distance from stick and tip to tank is more than 50 mm

Note that the conductivity of liquids are temperature dependent.
For absolute conductivity measurement, the cell constant must fit the tank diameter.

Typical conductivity examples
Fresh cow milk: 4-5 mS/cm
Tap water: 0.005 to 0.5 mS/cm (soft to hard water)
CIP liquid: 100 mS/cm (water with 2% NaOH or HNO3)

Different measurement situations with and without foam

Without foam
1. Valid liquid level and conductivity.
2. Valid zero liquid level and conductivity.
3. Invalid zero liquid level. Conductivity out of range.
Tip must be covered by liquid.

With foam
4. Valid equivalent liquid level of foam and conductivity.
5. Valid equivalent liquid level of foam and conductivity.
6. Invalid foam level.
Zero level if foam conductivity is out of range.
Tip must be covered by liquid.

Analogue Current Output
Signal range (source): 0 – 22 mA
Calibration error: @ Tamb. 20 °C Max. +/- 0.1 % of full scale
Temperature coefficient: Tc Max. +/- 150 ppm / °C
Resolution: 0.06 % of full scaleDigital Input (referenced to -24 Vin)
Frequency. Max. 1 kHz @ 50 % duty cycle
Input On: Vin < 4.5 V, Off: Vin > 6.5 V
Hysteresis: Typ. 1 V
Line check: (*
Line open voltage: >0.75 * Vin
Line short circuit voltage: < 2 V
Input pull down resistance: 6.8 kΩ
Input active pull up (configurable): 3 mADigital Output (source)
Oneshot and Dutycycle time resolution: 417 µs
Internal resistance: Typ. 0.5 Ω
Output start current (duration max 200 ms): Typ. 5 A
Load current at ON (Source only): Max. 0.5 A
Short circuit cutoff delay time (current > 5A): 104 µs
Leak current at OFF: Max. 500 µA

Level Measurement
Range: lenght of Dipstick (fx. 0.700 m)
Accuracy: 0.005 m
Resolution: 0,0001 m
Update frequency: 100 msConductivity Measurement
Range: 0.001 mS/cm to 100 mS/cm
Accuracy: (uncalibrated) +/-30 %
Resolution: 0,1 mS/cm
Update frequency: 100 msTemperature Measurement
Process temperature range: 0-100 °C
Calibration error: @ 20 °C +/-0.6 °C
Resolution: 0,1 °C
Update frequency: 200 ms

Power Specifications
Supply voltage: nominal 24 VDC
Supply voltage: 12 – 32 VDC
Typ. internal power consumption: (@ 24 VDC) 0.5 W

Environmental Conditions
Operation temperature: -25 °C to +70 °C
Storage temperature: -40 °C to +85 °C
Protection class: IP67

MECHANICAL (mm)

Mechanical Specifications
Weight approx (lenght 500 mm): 1600 g
Vibration: IEC 60068-2-6 : 2007

Tank part

P-NET FIELDBUS INFORMATION

P-NET INSTALLATION

P-NET IP

PD940 DIPSTICK

Product Description

PD 940 - DIP-STICK