Load Cell Systems

When accuracy counts

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I t d tiIntroduction

Understanding weighing system options

Choosing between STANDARD and HI-TECH systems

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T i f Di iTopics of Discussion

Assess the need to weighEvaluate the risksEvaluate the risks Understand the different optionsA l th b t t h l il blApply the best technology availableBatch reports

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A th d t i hAssess the need to weigh

Proportions of ingredients critical to a good finished productToo much or too little of one ingredient could spell disaster in th fi l d tthe final productNeed ability to record reliabled t f f t f i thdata for future reference in the event of problems down the road

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Evaluating the Risks

If any one of the ingredients batched is an incorrect amount, what happens to the end product?the end product?Could an incorrect weighment be a “minor inconvenience” or a “major problem”?What tolerances can you live with?How important is the need to recordHow important is the need to record ACCURATEACCURATE batch data for future reference?

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STANDARD Weighing SystemLoad cells with millivolt output in proportion to the load applied. Junction box to terminate load cells and perform corner matching (manually done with test weights applied to hopper at g pp ppeach load cell.)Digital weight indicator to read load cell signal and convert to weight displaysignal and convert to weight display. Requires communication option to interface to PLCN i i f i fNo monitoring for proper operation of load cell systemActual calibration needs to be performed

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pmanually with weight application

Hartman Scale “HI-TECH” Weighing System

Redundant weighing systems to g g yASSURE proper weighment (Batch scale and Check scale)

Scale integral to PLC control system withScale integral to PLC control system with automatic calibration capabilityIntelligent Junction box for continual gevaluation of load cells Automatic test weight application on periodic basis for ultimate verificationperiodic basis for ultimate verification

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Understanding “Electronic Calibration” TechnologyElectronic Calibration provides quick and easy electronic calibration of your weighing system. A standard system includes load cells, junction box, cabling and instrumentation and is designed to makecabling and instrumentation, and is designed to make initial and follow-up calibration easier than ever before. Upon installation or re-calibration, the instrument automatically searches for certified load cells and

d th f h t i ti E t irecords the performance characteristics. Entering a reference point is all that’s needed to bring your system on line within seconds. Each individual load sensor has its performance characteristics stored on an internal memory device within the load cell. These characteristics are measured on National Institute of Standards and Technology (NIST) traceable test devices and gy ( )electronically recorded when the sensor is manufactured. The Electronic system uses these parameters, the instruments’ characteristics and a reference point to

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instruments characteristics and a reference point to calibrate the scale system AUTOMATICALLY

LOAD CELL DETAILS

Load cells: Should be hermetically sealed to IP68 Standards (Welded shut assealed to IP68 Standards (Welded shut as

opposed to cover plates adhered by mechanical means) to prevent water ingress in the event of

t h dwater wash-down.Individual Load cell information will be available for continual evaluation toavailable for continual evaluation to address problems such as electrical malfunction or mechanical interference.Load cells are approved for use in Class 1 Division 1 Group A,B,F, and Gwith proper barrier strips provided

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with proper barrier strips provided.

“INTELLIGENT” JUNCTION BOX DETAILS

Intelligent Junction BoxThe Intelligent Junction Box troubleshoots your weighing g y g gsystem and diagnoses problems via the PLC.

The Intelligent Junction Box lowers weighing system maintenance costs and down time by enabling users to y gquickly troubleshoot and diagnose many weighing system problems.

Maintenance tests can be run from PLC or SLC using the gIntelligent Junction Box. These tests display system weights, voltages, and pass/fail displays to help isolate a problem to the instrument, cabling, or sensors. One test even provides internal references to test the integrity of the instrument, the cable to the junction box and the junction box itselfcable to the junction box, and the junction box itself.

Invaluable when used to assess operation of the weighing system on regular “preprogrammed” intervals via the PLC

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PC Weigh Module / Virtual Weight Indicator

The Virtual indicator provides the following features:

•Web browser-based iQUBE cell status

•Configurable display options

•Virtual front panel consists of display and five button keypad

Primary/secondary units configuration (lb kg short tons metric tons none)•Primary/secondary units configuration (lb, kg, short tons, metric tons, none)

•RS-232 communications at up to 57.6 Kbps

•Electronic data processing (EDP) port over RS-232 and TCP/IP

•Provides for intelligent configuration

•Supports intelligent junction box diagnostics with configurable error reporting

•Peak weight history

•Recalibration notification

•Provides local and remote reporting of diagnostics and error conditions

•NTEP Certified for Classes III and IIIL at 10 000 divisions

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•NTEP Certified for Classes III and IIIL at 10,000 divisions

PLC WEIGH MODULE The 1769-WS conditions and digitizesthe weight signal fifty times per secondwith over eight million counts of

The compact weigh scale module that Hartman Scale offers is available in Single channel or dual channel models

with over eight million counts ofresolution over a differential signalrange of 0 to 15mV. It then transmits theselectable Gross,Net and/or Diagnosticsd t t th Thi hi h

For use with the Allen-Bradley Micro-LogixTM 1500 and CompactLogix®controllers.The 1769-2WS and1769-WS read and condition data to the processor.This high

resolution enables the module totolerate large dead loads and over

sizingf th l d hil t i i

1769 WS read and conditionweight and diagnostic data fromstrain gauge load sensors or loadcells and communicate this data overth I/O h i b k l t th of the load sensors, while retaining a

high level of usable resolution.Themodule supplies 5 volts of DC excitationto drive up to four 350-ohm load cells

the I/O chassis back-plane to theMicro-LogixTM 1500 or CompactLogix®processor. Both modules reduceinstallation costs, as they do not

associated with a single scale (-WS), It will support additional load cells withan external power supply.

require an external stand-alone scaleinstrument with a wired communicationslink to the PLC.

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HARTMAN SCALE PLC Program Features The PLC program Hartman Scale developed for batch or continuous feed applications has been inThe PLC program Hartman Scale developed for batch or continuous feed applications has been in

development over several years. Each new application leads to developing new and unique features. The benefit is our customers get a program that has been fine tuned and tested.

AUTOMATIC Interrogation of load cell system with “INTELLIGENT” junction box for PASS / FAIL RESULT. PROCEED IF PASS, ALARM IF FAILREQUIRE ZERO FEATURE: Verifies the weight on the scale is at a zero setting (empty) to within pre-specified tolerances.

Different levels can be entered for below zero and above zero.AUTO TARE: Scale will be put in the net mode and “zeroed”BATCH AT FAST SPEED: The analog output of 4-20 ma will be sent to controller for Feeder to run the feeder at desired fast speed. The Fast speed optimization feature automatically determines the speed setting use for fastest throughput of product.BATCH AT SLOW SPEED: The analog signal will switch to the preset slow speed setting to more accurately stop at the target weight The Slow Speed Optimization featureto more accurately stop at the target weight. The Slow Speed Optimization feature automatically determines the slow speed setting and where to switch to the slow speed to more accurately be able to stop at the desired target weight.AUTO PREACT: Feature automatically accounts for the material that is “in suspension” between the end of the feeder tube and the weigh scale. By stopping the feed slightly before the TOLERANCE CHECKING: Verifies that the final weight in the scale is within preset tolerances for the “Over” and “Under” readings preset. If Batch is over weight the alarm output is energized. If the batch is under weight the auto jog feature is enabled.AUTO JOG: Automatically adds additional product to the weigh hopper by running the feeder for short time period at preset speed to deliver the required material to the batch.MATERIAL REPLENISH MID-BATCH: In the event the bulk bag becomes completely

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MATERIAL REPLENISH MID-BATCH: In the event the bulk bag becomes completely discharged “mid batch” the batch will automatically pause and the alarm output will be energized to alert the operator that the bulk bag needs to be replaced. Batch can be resumed once the bulk bag is replaced.

Automatic Test Weight ApplicationThe most accurate way to calibrate or check the calibration of a scale is to apply certified “MASS” weights to the scale at severalMASS weights to the scale at several increments

With automation control via the PLC the testWith automation control via the PLC the test weights that are located below the weigh hopper are lifted onto the scale via pneumatic cylinders.

Weight readings are verified and documented as part of the calibration check procedure.

The operator is alerted to errors that are found to be outside acceptable tolerance so that corrections can be made

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corrections can be made.

Wh t Thi MWhat This MeansACCURATE WEIGHTS are PARAMOUNT for accurate batches

Continuous monitoring of the system components assures scale systems are operating properly and within specifiedoperating properly and within specified tolerances

fMore confidence that the end product will perform as required

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Calibration Reporting

Every automatic calibration is loggedEvery automatic calibration is logged to Microsoft Access data base program

Reporting format can be tailored with the information you require

Industrial PC can be provided as operator interface with the system oroperator interface with the system or logged data can be made available to a remote PC via Ethernet

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Sample Report Format

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RESULTS:RESULTS:

Stored Calibration data can be invaluable for evaluating problems down stream in the manufacture process

Knowing the weighing system is ti l i foperating properly gives peace of

mind that the end product will perform as required

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perform as required.