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. Suppose that you are responsible for computerizing a gourmet restaurant's order-entry system.What types of input device do you think would work best for waiters to input order to the kitchen?
Roman Arshad
I think a computer that had buttons which will send it to the chef instead of a waiter would be nice! Also, the waiter will become the teller and tell the chef what to cook based on the button! Does that sound nice?
Adhruth
Adhruth
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What is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is a systemWhat is?
A system is a set of interacting or
Central nervous systemWhat is blood brain barrier How important is it in epilyptic patients?
How is the blood brain barrier important to patient care?
When assembling a systemwhat order do you put components into the case?
You can assemble them in any order you like - whichever is most convenient for you. People usually install the chips into the motherboard before installing it into the case, followed by video card, modem car etc, and power supply.
In a rack-and-pinion steering systemwhat protects the rack from contamination?
The rack has pleated rubber boots that seal the ends of housing, holding in the grease and keeping out the dirt, but allow the tie rods to extend and retract. The sector shaft would be sealed with a seal pressed in above the bearings. Some systems have a filter screen in the fluid reservoir.
What if your friend is very worried by rumors that he has heard about a substance called dihydrogen monoxide in the city's water systemWhat can you say to your friend to calm his fears?
Dihydrogen monoxide is running in the city's water system, and it should be! If we look at the compounds name, we have two hydrogen atoms, and one oxogen atom, thus the chemical formula for Hihydrogen monoxide is H2O. Silly, its just water!
What are the two types of economic system that Canada has?
canada_has_mixed_economic_system">canada_has_mixed_economic_system">canada has mixed economic systemwhat specifically are the economic systems??? There Are no economic System"s" Just one Classification of the Economy But I think you're thinking about the government classification. If you Want to know, Canada's Government is classified as a CONSTITUTIONAL MONARCHY. If you are looking for the economic system of Canada, It is classified as a MIXED ECONOMY but it is more market than command.Made by DumbMuffin
What if analysis in management information system?
Summary of What-if Analysis¡ What-if analysis is a brainstorming approach that uses broad, loosely structured questioning to:1. Postulate potential upsets that may result in accidents or system performance problems2. Ensure that appropriate safeguards against those problems are in place.Brief summary of characteristics¡ A systematic, but loosely structured, assessment:l team of experts brainstormingl generate a comprehensive reviewl ensure that appropriate safeguards are in place¡ Typically performed by one or more teams with diverse backgrounds and experience¡ Applicable to any activity or system¡ Used as a high-level or detailed risk assessment technique¡ Generates qualitative descriptions of potential problemsl in the form of questions and responsesl lists of recommendations for preventing problems¡ The quality of the evaluation depends on:l quality of the documentationl training of the review team leaderl experience of the review teamsMost common uses¡ Generally applicable for almost every type of risk assessment applicationl especially those dominated by relatively simple failure scenarios¡ Occasionally used alone, but most often used to supplement other, more structured techniquesl especially checklist analysisLimitations of What-if Analysis¡ Although what-if analysis is highly effective in identifying various system hazards, this technique has three limitations:Likely to miss some potential problems¡ The loose structure of what-if analysis relies exclusively on the knowledge of the participants to identify potential problems.¡ If the team fails to ask important questions, the analysis is likely to overlook potentially important weaknesses.Difficult to audit for thoroughness¡ Reviewing a what-if analysis to detect oversights is difficult because there is no formal structure against which to audit.¡ Reviews tend to become "mini-what-ifs," trying to stumble upon oversights by the original team.Traditionally provides only qualitative information¡ Most what-if reviews produce only qualitative results; they give no quantitative estimates of risk-related characteristics.¡ This simplistic approach offers great value for minimal investment, but it can answer more complicated risk-related questions only if some degree of quantification is added.Procedure for What-if AnalysisThe procedure for performing a what-if analysis consists of the following seven steps:Define the activity or system of interest.· Specify and clearly define the boundaries for which risk-related information is needed.2. Define the problems of interest for the analysis.· Specify the problems of interest that the analysis will address§ safety problems§ environmental issues§ economic impacts§ etc.3. Subdivide the activity or system for analysis.· Section the subject into its major elements§ locations on the waterway§ tasks§ subsystems)· The analysis will begin at this level.4. Generate what-if questions for each element of the activity or system.· Use a team to postulate hypothetical situations (generally beginning with the phrase "what if …") that team members believe could result in a problem of interest.5. Respond to the what-if questions.· Use a team of subject matter experts to respond to each of the what-if questions.· Develop recommendations for improvements wherever the risk of potential problems seems uncomfortable or unnecessary.6. Further subdivide the elements of the activity or system (if necessary or otherwise useful).· Further subdivision of the activity or system may be necessary if more detailed analysis is desired.§ Provide no more valuable information§ Exceed the organization's control or influence to make improvements.§ Generally, the goal is to minimize the level of resolution necessary for a risk assessment.7. Use the results in decision making.· Evaluate recommendations from the analysis and implement those that will bring more benefits than they will cost in the life cycle of the activity or system.1.0 Define the activity or system of interest¡ Intended functions.l Because all risk assessments are concerned with ways in which intended functions can fail, a clear definition of the intended functions is an important first step in any assessment.¡ Boundaries.l Few activities or systems operate in isolation.l Most interact with others.l The analyst should clearly define the boundaries of the study, especially areas where a vessel will transit, or boundaries with support systems such as electric power and compressed air.l In this way, the analyst can avoid the following:¡ Overlooking key elements of an activity or system at interfaces¡ Penalizing an activity or system by associating other equipment with the subject of the study2.0 Define the problems of interest for the analysis¡ Safety problems.l The analysis team may be asked to look for ways in which improper performance of a marine activity or failures in a hardware system can result in personnel injury.¡ These injuries may be caused by many mechanisms, including the following:l Vessel collisions or groundingsl Person overboardl Exposure to high temperatures (e.g., through steam leaks)l Fires or explosions¡ Environmental issues.l The analysis team may be asked to look for ways in which the conduct of a particular activity or the failure of a system can adversely affect the environment.¡ These environmental issues may be caused by many mechanisms, including the following:l Discharge of material into the water, either intentional or unintentionall Equipment failures, such as seal failures, that result in a material spilll Over utilization of a marine area, resulting in a disruption of the ecosystem¡ Economic impacts.l The analysis team may be asked to look for ways in which the improper conduct of a particular activity or the failure of a system can have undesirable economic impacts.¡ These economic risks may be categorized in many ways, including the following:l Business risks, such as vessels detained at port, contractual penalties, lost revenue, etc.l Environmental restoration costsl Replacement costs, such as the cost of replacing damaged equipment¡ A particular analysis may focus only on events above a certain threshold of concern in one or more of these categories.3.0 Subdivide the activity or system for analysis¡ An activity or system may be divided at many different levels of resolution.¡ Analysts should try to describe risk-related characteristics for an activity or system at the broadest level possible.¡ The procedure for subdividing an activity or system is typically repetitive, beginning with a broad subdivision into major sections or tasks.¡ This strategy of beginning at the highest level helps promote effective and efficient risk assessments by· ensuring that all key attributes are considered· encouraging analysts to avoid unnecessary detail· using a structure that helps to avoid overlooking individual components or steps if further subdivision is necessary.¡ Example· Systems associated with the vessel's compressed air system· Compressor system· Dryer system· Distribution system4.0 Generate What-If Questions¡ For each element of the activity or system¡ The brainstorming process is used by an analysis team to generate what-if questions.¡ Two different types of teams may be assembled to generate the what-if questions:¡ Team Type 1: Subject matter experts.· People are very knowledgeable about details of:¡ How the activity is conducted,¡ How the system is designed¡ Maintenance¡ Operation¡ Team Type 1: SMEl While they can perform an analysis very efficiently, their closeness to the activity or system may keep them from seeing some issues.¡ Team Type 2: OTPl Do a very thorough job identifying different types of possible issuesl Sometimes overlook subtle issues unique to the specific applicationl Spend too much time dwelling on unimportant issues.¡ Regardless of the type of team selected for brainstorming, the leader should observe the steps on the following page while conducting the analysis.Procedure for Generating What-If Questions¡ Step 1. Remind the team of the analysis scope and objectives¡ Step 2. Allow a few minutes for participants to collect their thoughts¡ Step 3. Explain how questions will be collectedl First or loudest voice (brainstorming)l Round robin (nominal group technique)l Circulating lists (brainwriting)¡ Step 4. Explain the rules for questionsl OK to ask any question whateverl OK to rephrase, combine, or broaden others' questionsl OK to speak out of turnl OK to answer questions about design intent or capability, but not what-if questionsl OK to use a prepared list of questionsl open brainstorming to collect top-of-the-headquestionsl focus brainstorming on specific process sections or subsystemsl seed the group with your own questionsl refocus the group only when several consecutive questions digress; expect and accept isolated irrelevant questionsl -use relevant checklist items to provoke additional questions¡ Step 5. Record the ideas as they are suggested:l generally on a flipchartl overhead transparencyl computer projection¡ Step 6. End the questioning after a reasonable time¡ Step 7. Organize the questions into logical groups for resolution;l combine closely related items as appropriatel eliminate overlapping questions5.0 Respond to the what-if questions¡ Each what-if question must be answered by a group of subject matter experts¡ Answering what-if questions generally defines the following:¡ Immediate system condition or response.· The initial changes in activity or system conditions that would occur if the postulated situation (i.e., the what-if) were to occur¡ Ultimate consequences of interest.· The eventual undesirable effects that the postulated situation could produce if it were not mitigated in some way.· Includes the worst-case outcome¡ as well as other significant, but perhaps less severe, outcomes of interest.¡ Safeguards· Equipment, procedures, and administrative controls in place to help¡ prevent the postulated situation from occurring¡ mitigate the effects if the situation does occur¡ Recommendations.· Suggestions for improvement that the team believes are appropriate· generally, suggestions for additional safeguards¡ There are three basic levels of documentation possible for a what-if analysis:· Completed - full responses for every question and a complete list of recommendations generated from the analysis· Streamlined - Responses to questions that result in suggestions for improvement, along with the complete list of recommendations generated form the analysis· Minimal - Complete list of recommendations generated from the analysis6.0 SubdivisionFurther subdivide the elements of the activity or systemActivityTasksStepsSystemsSubsystemsComponentsSubassembliesPartsFurther subdivision of activities or systems occurs only under the following conditions:Applicable data at the higher levels are not availableDecision makers need information at a more detailed levelOften, only a few activities or systems must be subdivided.If the above criteria apply to one or more subsystems, those subsystems may be further divided into components.In a similar manner, broad activities or tasks may be divided into individual steps.At each level, the process of performing the what-if analysis is repeated.ExampleSubsystems associated with the vessel's compressor systemElectrical supply to the compressorLubrication systemSeal systemDrive system, including the motorMechanical compression systemControl systemRelief systemFilter systemWhat-if analyses of any or all of those subsystems might occur if they were important systems from a risk perspective.7.0 Use the results in decision making¡ Judge acceptability.l Decide whether the estimated risk-related performance for the activity or system meets an established goal or requirement.¡ Identify improvement opportunities.¡ Identify elements of the activity or system that are most likely to contribute to future risk-related problems.l These are the items with the largest percentage contribution to the pertinent risk-related factors of merit (safety, environmental, economic).¡ Make recommendations for improvement.¡ Develop specific suggestions for improving the activity or system performance, including any of the following:l Equipment modificationsl Procedural changesl Administrative policy changes such as planned maintenance tasks, operator training, etc.¡ Justify allocation of resources for improvement.l Estimate how implementation of expensive or controversial recommendations for improvement will affect future performance.l Compare the risk-related benefits of these improvements to the total life-cycle cost of implementing each recommendation
How governing system of steam turbine is being done?
(pictures insert is not being allowed by wiki. i am sorry)TOPICS OF DISCUSSIONCONCEPT OF GOVERNING SYSTEMFEATURES OF KWU GOVERNING SYSTEMOVERVIEW OF GOVERNING RACKFUNCTIONING OF EHC CIRCUITSFREE GOVERNOR MODE OPERATIONBEST PRACTICES IN GOVERNING SYSTEMEMERGENCIES IN GOVERNING SYSTEMWHAT IS GOVERNING SYSTEM ?n Turbine Governing system is meant for regulation of turbine speed under no load and varying load condition.n It helps in precise control of grid frequency under normal operation and protects the machine as well as grid during emergency situation.KWU GOVERNING SYSTEM-FEATURESn ELECTRO-HYDRAULIC GOVERNING SYSTEM WITH HYDRAULIC BACKUPn OPERATION OF STOP VALVES BY STARTING & LOAD LIMITING DEVICE (HYDRAULIC)n ROLLING, SYNCHRONIZATION & LOAD OPERATION BY HYDRAULIC / ELECTRO- HYDRAULIC SYSTEMn ELECTRO- HYDRAULIC SPEED GOVERNOR WITH HYDRAULIC BACK UPn SAFE SHUTDOWN BY HYDRAULIC / ELECTRO- HYDRAULIC SYSTEMn ELECTRICAL AND HYDRAULIC PROTECTION SYSTEM ALONG WITH TEST FACILITIESFEATURES OF EHCn AUTO ROLLING & SYNCHRONIZATION THROUGH SPEED CONTROLLER UNDER INFLUENCE OF TSEn CONSTANT LOAD OPERATION BY LOAD CONTR. WITH PRESSURE CONTR. AS BACKUPn RUNBACK OPERATION THROUGH PRESSURE CONTR.n EMERGENCY OPERATION THROUGH SPEED CONTR.n AUTO GRID FREQUENCY CONTROL THROUGH EXTERNAL FREQUENCY INFLUENCEn AUTO UNLOADING AT HIGH FREQUENCY THROUGH INTERNAL FREQUENCY INFLUENCEn CONTROL DURING AUTOMATIC TURBINE TESTING,ISOLATED GRID CONDITION & LSR OPERATIONSPEED CONTROLLER CIRCUITL - Raise & Lower command from UCB :nr - Speed Reference :nr limit - Delayed Speed Reference :NLC - No Load Correction (Ensures required Speed controller O/P for Rolling even when Speed reference n r matches n act.)n act - Actual Speed :hr nc - Speed Controller O/P with DROOP of + / - 10.0 V for nr lim ~ n act = 150 RPM ( GAIN = 22LOAD SET POINT GENERATION CIRCUIT1 - SET POINT FOLLOW UP when Automatic Grid Control or CMC In service(Other Raise / Lower commands get blocked)2 -- TSE ENABLING whenA) GCB is closed ANDB) Load controller (L C) not OFF ANDC) Fast calibration signal 6 absent ANDD) I) Load controller (L C) in controlOR ii) Pressure controller with initial pressure in actionOR iii) Turbine follow mode in serviceThis helps to bring manually adjusted gradient and stress effect in service.+/- 10 V gradient => +/- 25 MW / MIN for 200 MW unitsOR +/- 50 MW / MIN for 500 MW units.PRESSURE CONTROLLER CIRCUITEHC TRANSFER CIRCUITFGMO - BACKGROUNDn Unique frequency band of 49.0 Hz to 50.5 Hz, as specified by IEGCn Scheduling & dispatch by RLDCs/SLDCs is based on day ahead demand & availabilityn Frequency control by load-generation balance in every 15 mins time blockn Wide frequency variation during Grid disturbance, Unit outage, change in demand, etc.n No primary response by generators to maintain frequency under such system contingencyn Emergencies caused due to frequency control only through importing /cutting load by system operatornFGMO - GRID CODESn All generating units should have their speed governors in normal operation at all times to enable Grid frequency control by loading / unloadingn Droop characteristic for primary response should be within 3% to 6%n Each unit shall be capable of instantaneously picking up at least 5% extra load for a minimum of 5 mins (up to 105%MCR), during fall in frequencyn No dead bands and/or time delays shall be deliberately introducedn Facilities like load limiters, CMC, etc. shall not be used to suppress the normal governor actionIMPLEMENTATION OF FGMOIn line with clause Clause 1.6 of IEGC and CERC order dated 30-10-99, date of FGMO implementation, as decided by REBs are :-n Western Region - 19-05-03 ( ABT - 01-07-02 )n Southern Region - 01-08-03 ( ABT - 01-01-03 )n Northern Region - 01-10-03 ( ABT - 01-12-02 )n Nor-East Region - 22-12-03 ( ABT - 01-11-03 )n Eastern Region - 02-01-04 ( ABT - 01-04-03 )FGMO CHARACTERISTIC FOR KWU M/CMAJOR ISSUES WITH FGMO IN 2004Ø Wide and frequent variation of freq.Ø Perpetual oscillations in critical parameters due to Boiler response timeØ M/C subjected to cyclic loading and fatigue stressesØ Frequent HP/LP Bypass valve operationØ Continuous manual interventionsØ Self-defeating feature(Unloading when freq. improving towards 50 Hz)Ø Conflict with ABT(Offsetting freq. correction)TRANSIENTS IN GOVERNING SYSTEMn FAILURE OF POWER PACKS OF CONTROLLER RACKS IN EHC PANELn POWER SUPPLY FAILURE IN ATRS PANELn SIGNAL ACQUISITION PROBLEMn FAILURE IN TURBINE SYSTEMn ELECTRICAL SYSTEM FAILUREn COMPONENT FAILURE IN GOVERNING RACKn OPERATIONAL EMERGENCY1 CONTROL RACK SUPPLY FAILUREn M/C is on EHC. Power supply fails in Load control/Pressure control / transfer circuit rack. Starting device becomes off automatically due to EHC fault.Observation: EHC output is minimum/zero and load minimum/ zero with EHC fault alarm. Machine on bar with ESV & IV open (Turbine not tripped).Action: Confirm HP/LP bypass opening, isolate EHC from governing rack and parallely adjust starting device position from UCB. Reduce boiler firing to restrict rise in boiler pressure.2) SUPPLY FAILURE IN ATRS PANEL(ATRS=Automatic Turbine Rolling & Synchronisation)n M/C is on EHC. Power supply fails in CCA panels only.Observation: All indication lamps in ATRS consoles will go off. EHC output and Load will become zero due loss of GCB close feedback. All ATRS drives will become inoperative.Action: Confirm HP/LP bypass opening , isolate EHC. Reduce boiler firing. Adjust starting device position from local. Normalize power supply in CCA panels at the earliest.3) SIGNAL ACQUISITION PROBLEMn Loss of speed signal occurs due to Hall Probe / card failure.Observation: Speed indication will become zero. M/C will be loaded through speed controller. Subsequently Pressure controller will come in service. AOP & JOP will take auto start & Barring Gear valve Will open on auto.Action: Isolate EHC and adjust Starting device position. If pressure oil pressure is normal, make SLC of AOP, JOP and Barring Gear vlv OFF and stop AOP, JOP and close Barring Gear vlv.4)FAILURE IN TURBINE SYSTEMn Loss of speed signal occurs due to breakage of MOP shaft.Observation: Speed indication and pressure oil pressure will come down. M/C will be loaded through speed controller and Pressure controller will come in service. Subsequently, AOP & JOP will take auto start &Barring Gear valve. will open on auto.Action: Safe shutdown of M/C is to be ensured.5) ELECTRICAL SYSTEM FAILUREn M/C is on EHC with Tracking on. Starting device becomes inoperative due to Electrical module trouble/motor failure/overload.Observation: During increase in boiler firing, Boiler pressure will increase due to load restriction by Starting device. EHC output will go to 100%.Action: Switch off the electrical module of Starting device and increase Starting device position from local so that EHC can take control.6) FAILURE IN GOVRRNING RACKn EHC Plunger coil failuren EHC Pilot valve bearing failureObservation: EHC starts huntingAction: Isolate EHC and take Hydraulic mode in service. Replace the failed omponent. Governing characteristic checking should be done before EHC is put in servicen Speeder Gear spring tension gets altered.Observation: M/C may get unloaded at frequency lower than recommended value.Action: Speeder Gear spring tension may be adjusted to increase the start of unloading.Testing for proper setting should be checked during suitable opportunity.LOGICSA SPEED CONTROLLER LOGICS1 Command for slow rate at nr > 2850 RPM to facilitate easy synchronisation2 TSE Influence ON, when min of all the upper stress margins comes into picture to control gradient of nr lim and hence, acceleration of Rolling speed. Upper stress margin = 30 deg C => 10.0 V => 600 RPM ~ (Acceleration < 108 RPM ~ causes dn / dt tripping)B LOAD SET POINT GENERATION LOGICS1 Stopping of nr lim whena) GCB open ANDb) n act is < nr lim by approx. 45 RPM.This restricts hr nc up to around 30 % during Rolling to avoid wide v/v opening.2 Stopping speed set point control when,a) n act > 2850 RPM ANDb) nr raised ( I.e, nr > nr lim) ANDc) I) TSE ON and faulted in GCB open conditionOR ii) Stop command from SGC in SGC ON condition.3 Tracking in synchronized condition ifa) Frequency within limit (adjustable, say 48.5 to 51.5 Hz.) ANDb) Load controller O/P , hr PC > hr nc ANDc) I) Load controller (L C) in controlOR ii)Pressure controller in action4 Set Point Follow Up (Fast Calibration) duringa) Tracking condition 5 ( nr = n act + 21 RPM ) ORb) Turbine Trip ( nr = n act - 120 RPM ). Simultaneously nr lim immediately equals to nrCondition (a) ensures certain speed controller O/P during emergency to keep machine in rolled condition along with some load.Condition (b) ensures negative speed controller O/P during Trip condition.LOAD CONTROLLER (L C) IN CONTROL CONDITIONS -a) Speed OR Pressure Controller not in action ANDb) Isolated Grid condition absent ANDc) Both Load Controller OFF and Schedule OFF absent (I.e, L C ON)LOAD CONTROLLER SCHEDULE OFF - L C can be made OFF if Speed controller is in action and hrnc > hr PC. Otherwise, with OFF command OFF lamp blinks - called Schedule OFFC .LOAD SET POINT GENERATION LOGICS1TSE ON AND NOT FAULTEDThis helps to keep stress effect for gradient control in service.2-- LOAD GRADIENT ONThis helps to keep manual gradient control in service3-- STOP POWER SET POINT CONTROL whena) TSE ON and Faulted ORb) Stop command from SGC ORc) Pr raised when Pressure controller is in action with CMC ON OR Limit pressure mode selected OR Boiler follow mode selectedIn above conditions Pr lim stops, I.e,Set point can not be increased.4-- FAST CALIBRATION whena) Pressure controller is in action ORb) Follow above (h v0) condition presentUnder this condition MW error (ep) is selected and Pr lim immediately equals to Actual load (P act) without any gradient .5 -- FREQUENCY INFLUENCE ONThis is made ON from ATRS panel to put EXTERNAL FREQUENCY EFFECT in service forloading / unloading w.r.t. 50 Hz ( with 2.5 % to 8 % Frequency Droop)6 TSE TEST RELEASE : TSE TEST (For checking healthiness of TSE Margins) can be done whena) TSE Influence is OFF ORb) Both Pr, Pr lim and hr, hr lim are balanced, I.e, Speed and Power set point controls are not in action.D .LOAD CONTROLLER LOGICSFOLLOW ABOVE ( h v0 ) --a) GCB closed and load < 10 % (station load) ORb) GCB open ORc) Load controller OFFAbsence of these conditions help Load controller output to track above Pressure controller output when Pressure controller is in service.FOLLOW LOW ( h vu ) - GCB CLOSED AND Speed controller in action.This helps Load controller output to track below Speed controller output.8 -- Either a) Initial pressure mode selected ORb) Turbine follow mode in action ORc) CMC Runback activeThis ensures Load controller output above pressure controller output9 -- Load controller OFFThis defeats transmission of Load Controller output to Transfer circuit.R & L - Raise & Lower command from UCB :nr - Speed Reference :nr limit - Delayed Speed Reference :NLC - No Load Correction (Ensures required Speed controller O/P for Rolling even when Speed reference n r matches n act.)n act - Actual Speed :hr nc - Speed Controller O/P with DROOP of + / - 10.0 V for nr lim ~ n act = 150 RPM ( GAIN = 22LOAD SET POINT GENERATION CIRCUIT1 - SET POINT FOLLOW UP when Automatic Grid Control or CMC In service(Other Raise / Lower commands get blocked)2 -- TSE ENABLING whenA) GCB is closed ANDB) Load controller (L C) not OFF ANDC) Fast calibration signal 6 absent ANDD) I) Load controller (L C) in controlOR ii) Pressure controller with initial pressure in actionOR iii) Turbine follow mode in serviceThis helps to bring manually adjusted gradient and stress effect in service.+/- 10 V gradient => +/- 25 MW / MIN for 200 MW unitsOR +/- 50 MW / MIN for 500 MW units.PRESSURE CONTROLLER CIRCUITEHC TRANSFER CIRCUITFGMO - BACKGROUNDn Unique frequency band of 49.0 Hz to 50.5 Hz, as specified by IEGCn Scheduling & dispatch by RLDCs/SLDCs is based on day ahead demand & availabilityn Frequency control by load-generation balance in every 15 mins time blockn Wide frequency variation during Grid disturbance, Unit outage, change in demand, etc.n No primary response by generators to maintain frequency under such system contingencyn Emergencies caused due to frequency control only through importing /cutting load by system operatornFGMO - GRID CODESn All generating units should have their speed governors in normal operation at all times to enable Grid frequency control by loading / unloadingn Droop characteristic for primary response should be within 3% to 6%n Each unit shall be capable of instantaneously picking up at least 5% extra load for a minimum of 5 mins (up to 105%MCR), during fall in frequencyn No dead bands and/or time delays shall be deliberately introducedn Facilities like load limiters, CMC, etc. shall not be used to suppress the normal governor actionIMPLEMENTATION OF FGMOIn line with clause Clause 1.6 of IEGC and CERC order dated 30-10-99, date of FGMO implementation, as decided by REBs are :-n Western Region - 19-05-03 ( ABT - 01-07-02 )n Southern Region - 01-08-03 ( ABT - 01-01-03 )n Northern Region - 01-10-03 ( ABT - 01-12-02 )n Nor-East Region - 22-12-03 ( ABT - 01-11-03 )n Eastern Region - 02-01-04 ( ABT - 01-04-03 )FGMO CHARACTERISTIC FOR KWU M/CMAJOR ISSUES WITH FGMO IN 2004Ø Wide and frequent variation of freq.Ø Perpetual oscillations in critical parameters due to Boiler response timeØ M/C subjected to cyclic loading and fatigue stressesØ Frequent HP/LP Bypass valve operationØ Continuous manual interventionsØ Self-defeating feature(Unloading when freq. improving towards 50 Hz)Ø Conflict with ABT(Offsetting freq. correction)TRANSIENTS IN GOVERNING SYSTEMn FAILURE OF POWER PACKS OF CONTROLLER RACKS IN EHC PANELn POWER SUPPLY FAILURE IN ATRS PANELn SIGNAL ACQUISITION PROBLEMn FAILURE IN TURBINE SYSTEMn ELECTRICAL SYSTEM FAILUREn COMPONENT FAILURE IN GOVERNING RACKn OPERATIONAL EMERGENCY1 CONTROL RACK SUPPLY FAILUREn M/C is on EHC. Power supply fails in Load control/Pressure control / transfer circuit rack. Starting device becomes off automatically due to EHC fault.Observation: EHC output is minimum/zero and load minimum/ zero with EHC fault alarm. Machine on bar with ESV & IV open (Turbine not tripped).Action: Confirm HP/LP bypass opening, isolate EHC from governing rack and parallely adjust starting device position from UCB. Reduce boiler firing to restrict rise in boiler pressure.2) SUPPLY FAILURE IN ATRS PANEL(ATRS=Automatic Turbine Rolling & Synchronisation)n M/C is on EHC. Power supply fails in CCA panels only.Observation: All indication lamps in ATRS consoles will go off. EHC output and Load will become zero due loss of GCB close feedback. All ATRS drives will become inoperative.Action: Confirm HP/LP bypass opening , isolate EHC. Reduce boiler firing. Adjust starting device position from local. Normalize power supply in CCA panels at the earliest.3) SIGNAL ACQUISITION PROBLEMn Loss of speed signal occurs due to Hall Probe / card failure.Observation: Speed indication will become zero. M/C will be loaded through speed controller. Subsequently Pressure controller will come in service. AOP & JOP will take auto start & Barring Gear valve Will open on auto.Action: Isolate EHC and adjust Starting device position. If pressure oil pressure is normal, make SLC of AOP, JOP and Barring Gear vlv OFF and stop AOP, JOP and close Barring Gear vlv.4)FAILURE IN TURBINE SYSTEMn Loss of speed signal occurs due to breakage of MOP shaft.Observation: Speed indication and pressure oil pressure will come down. M/C will be loaded through speed controller and Pressure controller will come in service. Subsequently, AOP & JOP will take auto start &Barring Gear valve. will open on auto.Action: Safe shutdown of M/C is to be ensured.5) ELECTRICAL SYSTEM FAILUREn M/C is on EHC with Tracking on. Starting device becomes inoperative due to Electrical module trouble/motor failure/overload.Observation: During increase in boiler firing, Boiler pressure will increase due to load restriction by Starting device. EHC output will go to 100%.Action: Switch off the electrical module of Starting device and increase Starting device position from local so that EHC can take control.6) FAILURE IN GOVRRNING RACKn EHC Plunger coil failuren EHC Pilot valve bearing failureObservation: EHC starts huntingAction: Isolate EHC and take Hydraulic mode in service. Replace the failed omponent. Governing characteristic checking should be done before EHC is put in servicen Speeder Gear spring tension gets altered.Observation: M/C may get unloaded at frequency lower than recommended value.Action: Speeder Gear spring tension may be adjusted to increase the start of unloading.Testing for proper setting should be checked during suitable opportunity.LOGICSA SPEED CONTROLLER LOGICS1 Command for slow rate at nr > 2850 RPM to facilitate easy synchronisation2 TSE Influence ON, when min of all the upper stress margins comes into picture to control gradient of nr lim and hence, acceleration of Rolling speed. Upper stress margin = 30 deg C => 10.0 V => 600 RPM ~ (Acceleration < 108 RPM ~ causes dn / dt tripping)B LOAD SET POINT GENERATION LOGICS1 Stopping of nr lim whena) GCB open ANDb) n act is < nr lim by approx. 45 RPM.This restricts hr nc up to around 30 % during Rolling to avoid wide v/v opening.2 Stopping speed set point control when,a) n act > 2850 RPM ANDb) nr raised ( I.e, nr > nr lim) ANDc) I) TSE ON and faulted in GCB open conditionOR ii) Stop command from SGC in SGC ON condition.3 Tracking in synchronized condition ifa) Frequency within limit (adjustable, say 48.5 to 51.5 Hz.) ANDb) Load controller O/P , hr PC > hr nc ANDc) I) Load controller (L C) in controlOR ii)Pressure controller in action4 Set Point Follow Up (Fast Calibration) duringa) Tracking condition 5 ( nr = n act + 21 RPM ) ORb) Turbine Trip ( nr = n act - 120 RPM ). Simultaneously nr lim immediately equals to nrCondition (a) ensures certain speed controller O/P during emergency to keep machine in rolled condition along with some load.Condition (b) ensures negative speed controller O/P during Trip condition.LOAD CONTROLLER (L C) IN CONTROL CONDITIONS -a) Speed OR Pressure Controller not in action ANDb) Isolated Grid condition absent ANDc) Both Load Controller OFF and Schedule OFF absent (I.e, L C ON)LOAD CONTROLLER SCHEDULE OFF - L C can be made OFF if Speed controller is in action and hrnc > hr PC. Otherwise, with OFF command OFF lamp blinks - called Schedule OFFC .LOAD SET POINT GENERATION LOGICS1TSE ON AND NOT FAULTEDThis helps to keep stress effect for gradient control in service.2-- LOAD GRADIENT ONThis helps to keep manual gradient control in service3-- STOP POWER SET POINT CONTROL whena) TSE ON and Faulted ORb) Stop command from SGC ORc) Pr raised when Pressure controller is in action with CMC ON OR Limit pressure mode selected OR Boiler follow mode selectedIn above conditions Pr lim stops, I.e,Set point can not be increased.4-- FAST CALIBRATION whena) Pressure controller is in action ORb) Follow above (h v0) condition presentUnder this condition MW error (ep) is selected and Pr lim immediately equals to Actual load (P act) without any gradient .5 -- FREQUENCY INFLUENCE ONThis is made ON from ATRS panel to put EXTERNAL FREQUENCY EFFECT in service forloading / unloading w.r.t. 50 Hz ( with 2.5 % to 8 % Frequency Droop)6 TSE TEST RELEASE : TSE TEST (For checking healthiness of TSE Margins) can be done whena) TSE Influence is OFF ORb) Both Pr, Pr lim and hr, hr lim are balanced, I.e, Speed and Power set point controls are not in action.D .LOAD CONTROLLER LOGICSFOLLOW ABOVE ( h v0 ) --a) GCB closed and load < 10 % (station load) ORb) GCB open ORc) Load controller OFFAbsence of these conditions help Load controller output to track above Pressure controller output when Pressure controller is in service.FOLLOW LOW ( h vu ) - GCB CLOSED AND Speed controller in action.This helps Load controller output to track below Speed controller output.8 -- Either a) Initial pressure mode selected ORb) Turbine follow mode in action ORc) CMC Runback activeThis ensures Load controller output above pressure controller output9 -- Load controller OFFThis defeats transmission of Load Controller output to Transfer circuit.
