Irrigation show april 2014
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Irrigation show, April 2014. Automation & Instrumentation in the Irrigation Sector James MacLellan – ABB Limited. Presentation topics covered. Accurate metering of water use and adherence to legislative requirements Optimising water usage Control of water quality standards

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Irrigation show april 2014

Irrigation show, April 2014

Automation & Instrumentation in the Irrigation SectorJames MacLellan – ABB Limited


Presentation topics covered
Presentation topics covered

  • Accurate metering of water use and adherence to legislative requirements

  • Optimising water usage

  • Control of water quality standards

  • Mitigation of electrical issues for the wider community

  • Managing energy efficiency



What is required
What is required?

  • Consent holders need to provide data regarding water takes.

  • Flow data needs to be within 5% of a known standard value*

    *ABB units are OIML R49 Type P.


So which device and why
So which device and why?

  • Mechanical Meters

    • Paddle wheel / Turbine / Gear.

    • Inexpensive& simple.

    • Accuracy limitations. Moving parts.

  • Coriolis Flow Meter

    • Uses principle of inertia for moving mass.

    • Extremely accurate, minimal install requirements.

    • Limitation on bore size. Expensive


So which device and why1
So which device and why?

  • Differential Pressure

    • Bernoulli’s Principle (> speed = < pressure).

    • Requires a constriction.

    • Not super ideal for irrigation sector.

  • Electromagnetic

    • Magnetic induction.

    • Without mechanical ‘moving’ parts.

    • Any ionic electrically conductive fluid.


Optimising water usage

Optimising water usage


Efficiency h 2 o transpired h 2 o applied x 100
Efficiency = (H2O Transpired / H2O Applied) x 100

Need to obtain some detail as to:-

  • How much water has been provided to the crop (applied)

  • How much water is absorbed by the crop (transpired)

    Need to MEASURE

  • Rainfall.

  • Soil depth.

  • Soil moisture.

  • Pasture response.

  • Irrigation application rate and efficiency.



Efficiency h 2 o transpired h 2 o applied x 1001
Efficiency = (H2O Transpired / H2O Applied) x 100

Soil temp @ 10cm depth < 10 deg C: Nil growth.

Soil temp @ 10cm depth > 10 deg C: Sun / Moisture.

---------------------------------------------------------------------------------

So, measure temperature @ 10cm depth.

Crop & Food Research: R.J Martin, S.M.Thomas, R.F. Zykowski

AgResearch: D.R Stevens



Pt100 thermistor rtd s
Pt100 & Thermistor (RTD’s)

Pt100

  • 0.385 ohms per degree C

  • LINEAR

  • Accurate

  • $$$$$$$

    Thermistor

  • Similar principle to Pt100

  • NON LINEAR

  • Not so accurate

  • Cheap!


Soil moisture content
Soil moisture content

Possible methods:-

  • Capacitance

  • Resistance

  • Conductivity

  • Temperature

Most common:-

  • Time Domain Transmission

  • Electrical pulse

  • Time / size affected by surrounding media


Time domain transmission
Time Domain Transmission

  • Conditions constant.

  • Repeatable result.

  • Imagine the wall changes…

  • The speed, time & force of the returning ball will very.

  • Alter one ‘constant’.

  • Results vary

  • Moisture change = change in pulse signal properties


The electro magnetic flow meter
The Electro-Magnetic Flow Meter

  • 3rd Law of induction (1832).

  • Left Hand Rule (motors).

  • mV signals generated

  • Electro-magnetic field ‘switches’.

  • mV signal size proportional to flow.



Chemical analysis
Chemical analysis…

  • pH (measure of acidity / alkalinity)

  • Conductivity (measure of ionic concentration)

  • Turbidity (measure of the particulates)



Nitrate dissolved oxygen analysis
Nitrate & Dissolved Oxygen Analysis

  • Leaching

  • Human health issues

  • Death of fish & marine species

  • Affect soil nutrition (< Ca)

  • Reduced by decomposition of organics (>BOD)

  • Affect aquatic species


Mitigation of electrical issues m anaging energy efficiency

Mitigation of electrical issues& managing energy efficiency



Getting the water the crowded room
Getting the WaterThe crowded room

  • Energy required to ‘lift’ or ‘pump’ water.

  • Most efficient use of electrical energy via VSD / VFD.


Variable speed drives vsd vfd
Variable Speed Drives (VSD / VFD)

  • Extremely efficient devices with regard to power use.

  • ‘Raw’…VSD’s can cause huge power issues across networks and disrupt/distort instrument signals

  • If you install them 100%...The instrumentation guy is happy…Everybody is happy


Sending the signals miscommunications
Sending the signalsMiscommunications


Common issues missing data
Common issues – Missing data

Conventional

  • Flow data via pulses.

  • Telecommunication fail.

  • Pulses / units disagree.

  • Punch up.

Serial communication

  • Flow data via digital comms

  • Receiver reads instrument value from a register

  • Doesn’t matter if communications are intermittent

  • MODBUS



Le chatelier s principle
Le Chatelier’s Principle




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