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Standard Technical Features of BTG System for Supercritical 660 ...

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<strong>Standard</strong> <strong>Technical</strong> <strong>Features</strong> <strong>of</strong> <strong>BTG</strong> <strong>System</strong> <strong>for</strong> <strong>Supercritical</strong> <strong>660</strong>/800 MW Thermal Unitsb) All analog signals <strong>for</strong> control purpose shall be acquired, validated,processed and their respective data base updated at a maximuminterval <strong>of</strong> 250 milli-seconds except <strong>for</strong> some fast-acting controlloops <strong>for</strong> which the above-referred time shall be as per processrequirement. For signals required <strong>for</strong> in<strong>for</strong>mation only, the abovefunctions shall be per<strong>for</strong>med at an interval <strong>of</strong> within 1 second.c) The 4-20 mA input analog cards shall be suitable <strong>for</strong> interfacingtransmitters giving 4-20mA analog signal along with superimposedHART interface signals. 4-20 mA DC signal will only be used <strong>for</strong>control purpose and superimposed HART signal will be used <strong>for</strong>configuration, maintenance diagnostic and record keeping facility <strong>for</strong>electronic transmitters and analysers etc. For non-HART 4- 20mAanalog inputs, conventional non-HART AI module shall be applied.ii)Binary Signal Conditioning & Processinga) The changeover type contacts (i.e. 'NC' + 'NO' together) shall bewired to the control system <strong>for</strong> all the binary inputs required <strong>for</strong>control purposes, except <strong>for</strong> inputs from MCC/switchgear, actuatorsand inputs related to hardwired signal exchange among variousfunctional group <strong>for</strong> which non-changeover type contacts ('NC' or'NO') shall be wired to the control system. The binary inputsrequired <strong>for</strong> in<strong>for</strong>mation purposes only shall be wired to controlsystem in the <strong>for</strong>m <strong>of</strong> non-changeover type contacts.b) The conditioning and processing functions to be per<strong>for</strong>med as aminimum <strong>for</strong> the binary inputs coming <strong>for</strong> control and in<strong>for</strong>mationpurposes shall be:1. 24V/ 48 V DC power supply <strong>for</strong> contact interrogation <strong>for</strong> allpotential free contacts with per point fuse protection or suitablecurrent limit feature/ isolation through opto-coupler.2. Contact bounce filtering delay time <strong>of</strong> 15 milliseconds.3. Facility <strong>for</strong> pegging the binary signal to logic one/zero or lastcorrect value in case <strong>of</strong> failure <strong>of</strong> binary input module.4. Binary signal distribution to different users shall be in such away so as to ensure that a short/ground fault on one user is notreflected to the other user.5. Implementation <strong>of</strong> multiple measurement schemes <strong>for</strong> signals<strong>for</strong> control purpose.6. All binary signals shall be acquired, validated, processed, alarmchecked and their data base updated within one second. Inaddition to this requirement, binary signals required <strong>for</strong> SOEshall have a resolution <strong>of</strong> 1millisecond.140

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