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MODIFICATION OF

CONTROLCIRCUIT OFCHRONOS MAKE

BAGGING ANDWEIGHINGMACHINES

V.P.K. Unni M(Instruments)G.G.Joshi Ch. Tech (Instruments)

20th Aug 2010

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Welcome

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INTRODUCTION

 The Chronos make Bagging & WeighingMachines were installed in the Baggingplant at Kandla in the year 2000. There

are 8 slat conveyors and above eachslat conveyors two nos. of weighingmachines are attached with a common

discharge hopper. So there are a total16 nos. of weighing machines.

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Main parts of theMachine are

1) Feed gate assembly – Single feed gate withtwo step operation with pneumatic cylinders.

2) Weighing Bucket.

3) Two Nos. of Load cells attached to theweighing bucket to sense the load.

4) Discharge gate assembly – operated byPneumatic cylinders.

5) 8 VDC Proximity switch attached to weighingbucket.

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Main parts of theMachine are

6) 110 VAC Knotex relay.

7) Metal plate attached to discharge gate tosense the closure of discharge gate through

8 VDC switch & Knotex relay.8) Sack grip – operated by pneumatic cylinders.

9) Proxy switch-attached to sack grip whichsenses the closure of sack grip.

10)2 No. of Speedac Microprocessor basedcontrollers mounted in control room (one foreach machine).

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Main parts of theMachine are

11) One No. Programmable Logic Controllor(PLC) – common for both machines, whichdiscriminates the earlier occurrence of 

balance in the machines.12) Local Control Panel – for operation like

start, stop, weighment selection, manualsack release, clearing Hold signal etc.

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OPERATION There is a selector switch in the

Local control panel by which we canset the target wt 25, 40, 50Kg asdesired.

Once the target wt. is set and

the bucket is empty, load cell givessignal to the controller equivalent tozero load. The closure of dischargegate is ensured by the metallic plate

8VDC & Knotex relay. If the dischargegate is closed the metallic plate willbe in contact with proxy switch whichin turn operates the knotex relay.

 The knotex relay contact sends signal

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Controller now issues signal tothe two feed gate solenoid valveswhich operates the feed gate in two

steps – rough & fine feed and thefeed gate will be opened fully. Whenapprox 40 Kg material is fed to theweigh hopper the controller willwithdraw signal from the rough feedsolenoid valve and the rough gatewill close. Now the material flow will

be throttled and wen 50Kg materialis fed into the bucket the controllerwill withdraw signal from the finefeed sv. and the feed gate will be

closed completely. Now the“

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When the Bag filler presses the“U” proximity switch , bag will begripped in the sack grip through

cylinders. The closure of sack grip issensed by a proxy switch on the sackgrip which sends signal to PLCensuring the gripping of spout. Nowthe PLC will send O.K. to dischargesignal to the controller whoseBalance occurred earlier. The

controller will now give dischargesignal to the corresponding weighingmachine. Discharge gate will openand material will be discharged into

the bag. The bag will be released

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CLOSURE OF DISCHARGE GATE TO THECONTROLLER IS NECESSARY. PREVIOUSLY THE CLOSURE OF DISCHARGE GATE IS

SENSED BY A METALLIC PLATE WHICHOPERATES 8VDC PROXY SWITCH WHICH INTURN ENERGIZES A KNOTEX RELAY WHICHFURTHER SENDS SIGNAL TO THE SPEEDAC

CONTROLLER ENSURING THE CLOSURE OFDISCHARGE GATE. DURING RAINY SEASONOR WHENEVER THERE IS MOISTURE,THEKNOTEX RELAY & THE 8VDC SWITCH GETS

SHORT CRICUITED AND GETS BURNT.SEVERAL KNOTEX RELAYS & 8 VDCSWITCHES WERE BURNT AND DOWN TIMEWAS INCREASING.

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 Today’s Overview

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Learning Objectives

•  Technology

• Procedure

•

Policies• Benefits

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NEWWORK 

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New Work

 The technology learningcurve

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Who’s Who

Lead Contact information

 Jim  Jim@company.com

Dee Dee@gcompany.com

Mavis Mavis@company.com

Doug Doug@company.com 

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 Time Spent

Pro

ject s

Work

ed

On

Get Familiar

AchieveMastery

Working Toward Mastery

GetExperienced

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Doing Your Best Work

• Working from home

• Working offsite

•  Technologyrequirements

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Case Study

•  Jeremy

 – His first day

 – Mistakes made

 – Successesachieved

 – The moral of the

story

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Discussion

• What we canlearn from Jeremy

• Best practices

•  Take-aways

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Summary

• Define your challenges

 – Technological as well as personal

• Set realistic expectation

 – Mastery is not achieved overnight

• Keep your eye on the goal

 –

Mentorship programs

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Resources

• <Intranet site text here><hyperlink here>

• <Additional reading material text here><hyperlink here>

•  This slide deck and related resources:

<hyperlink here>

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QUESTIONS?

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APPENDIX