A particle of mass m and positive charge q is projected from the point P. Find the smallest value of the speed v such that the particle does not return to P. The 1st ball touches the ground at a distance l from the initial vertical. At what height will the 2nd ball be at this instant?
Two concentric rings of radii r and 2r are placed with centre at origin. Find the work done by electrostatic forces in each step. A positive charge Q is uniformly distributed throughout the volume of a dielectric sphere of radius R. Neglect any resistance other than electric interaction.
Charge on the small mass remains constant throughout the motion. An electrometer consists of vertical metal bar at the top of which is attached a thin rod which gets deflected from the bar under the action of an electric charge fig. The reading are taken on a quadrant graduated in degrees. The length of the rod is l and its mass is m. The distance between the centres of the sphere and the cavity is a.
How long will it take to touch the sphere again? In what proportion will the velocity of the second ball changes? Electrically charged drops of mercury fall from altitude h into a spherical metal vessel of radius R in the upper part of which there is a small opening. The kinetic energies of the released balls are found to differ by K at a sufficiently long distance from the polygon. Determine the charge q of each part. Find the ratio between the charges on the 2 balls at which electrostatic energy of the system is minimum.
What is the potential difference between the 2 balls? Total charge of balls is constant. The charged density i. It is then placed on a rough nonconducting horizontal surface plane. Determine the friction force magnitude and direction acting on the ring, when it starts moving. Calculate the energy required to take a test charge q from infinity to apex A of cone.
The slant length is L. An electron is released on the axis of the hole at a distance 3R from the centre. What will be the velocity which it crosses the plane of sheet. A metallic solid sphere is placed in a uniform electric field. A non-conducting ring of radius 0. Take the electric Q. A conducting sphere S1 of radius r is attached to an insulating handle. Another conducting sphere S2 of radius R is mounted on an insulating stand.
S2 is initially uncharged. This procedure is repeated n times. Find the electrostatic energy of S2 after n such contacts with S1. A positive charge q is placed at the center of the cavity. The particle has. Sketch the potential energy of the particle as a function of its height and find its equilibrium position. Find the least value of v0 for which the particle will cross the origin.
Find also the kinetic energy of the particle at the origin. Assume that space is gratity free. Three positive charges of equal value q are placed at the vertices of an equilateral triangle. The resulting lines of force should be sketched as in [JEE Scr ]. Another identical ball having the same charge is kept at the point of suspension. Determine the minimum horizontal velocity which should be imparted to the lower ball so tht it can make complete revolution.
Which of the following electric force pattern is correct? Assume that the charge Q does not affect the charge distributions of the sheets. What is the electric field at P.
If the bubble collapses to a droplet, find the potential on the droplet. Find the work done to separate the charges to infinite distance. Capacitance Index: 1. This sphere is at infinite distance from all the conductors. Here capacitance of region between the two shells is C1 and that outside the shell is C2. We have. Cn C1 C2 C3. The capacitors have the same potential difference, V but the charge on each one is different if the capacitors are unequal.
This energy is stored in the electrostatic field set up in the di-electric 2 2 2 C. In this process energy is lost in the connecting wire as heat. A solid conducting sphere of radius 10 cm is enclosed by a thin metallic shell of radius 20 cm. Find the heat generated in the process, the inner sphere is connected to the shell by a conducting wire. When the switch S is closed. Find a the amount of charge flown through the battery b the heat generated in the circuit c the energy supplied by the battery d the amount of charge flown through the switch S.
Find the final potential difference between the plates of the first capacitor. The two identical parallel plates are given charges as shown in figure. If the plate area of either face of each plate is A and separation between plates is d, then find the amount of heat liberate after closing the switch. Find the value of C. After disconnecting from the voltage sources. These capacitors are connected as shown in figure with their positive polarity plates are connected to A and negative polarity is earthed.
When switch is closed, find : the potential of the junction A. Find the effective capacitance between X and Y. Two parallel sided dielectric slabs of thickness 0. If the dielectric constants of the two slabs are 3 and 5 respectively and a potential difference of V is applied across the plates. Find : i the electric field intensities in each of the slabs.
List of recommended questions from I. Find the potential difference across all the capacitors. The gap between the plates of a plane capacitor is filled with an isotropic insulator whose di-electric.
The area of the plates is S. Determine the capacitance of the capacitor. Find ; the effective capacity of the system between the terminals of the source. A potential difference of V is applied between the plates of a plane capacitor spaced 1 cm apart. A plane parallel glass plate with a thickness of 0. The drop of potential in each layer. The surface charge density of the charge on capacitor the plates.
The plates of first capacitor move towards each other with relative velocity 0. Find the current in the circuit at the moment. A battery charges the plates to a potential difference of V0. A capacitor of capacitance C0 is charged to a potential V0 and then isolated. The potential of the large capacitor has now fallen to V. Find the capacitance of the small capacitor. Is it possible to remove charge on C0 this way? When the switch S in the figure is thrown to the left, the plates of capacitors C1 acquire a potential difference V.
Initially the capacitors C2C3 are uncharged. Thw switch is now thrown to the right. A parallel plate capacitor with air as a dielectric is arranged horizontally. The lower plate is fixed and the other connected with a vertical spring.
The area of each plate is A. In the steady position, the distance between the plates is d0. When the capacitor is connected with an electric source with the voltage V, a new equilibrium appears, with the distance between the plates as d1.
Mass of the upper plates is m. Find the spring constant K. What is the maximum voltage for a given K in which an equilibrium is possible? What is the angular frequency of the oscillating system around the equilibrium value d1. If q is the charge on the conductor after the first operation, prove that the maximum charge which can be given to the conductor in this way is. Determine the final voltage Vf across the capacitors. A capacitor consists of two air spaced concentric cylinders. The outer of radius b is fixed, and the inner is of radius a.
Find the electrostatic energy of the system stored in the region I and II. Find the charge on the rightmost capacitor as a function of time given that it was intially unchanged. Calculate the capacitance of A and the energy stored in it. Find the work done by the external agency in removing the slab from A. Calculate the energy stored in the system. Two square metallic plates of 1 m side are kept 0. The plates are connected to a battery of e.
The plates are then lowered vertically into the oil at a speed of 0. Calculate the current drawn from the battery during the process. Another capacitor of capacitance 2C is similarly charged to a potential difference 2V volt. Find the capacitance of the resulting capacitor. The plates of the capacitors are connected as shown in figure with one wire from each capacitor free. The upper plate of a is positive and that of B is negative.
Calculate : the final charges on the three capacitors The amount of electrostatic energy stored in the system before and after the completion of the circuit. Also plot the variation of current with time.
An electron enters the region between the plates of a parallel plate capacitor at a point equidistant from either plate. A potential difference of volt is kept across the plates. Assuming that the initial velocity of the electron is parallel to the capacitor plates, calculate the largest value of the velocity of the electron so that they do not fly out of the capacitor at the other end.
For the circuit shown, which of the following statements is true? Two identical capacitors, have the same capacitance C. One of them is charged to potential V1 and the other to V2. The negative ends of the capacitors are connected together. When the positive ends are also connected, the decrease in energy of the combined system is [ JEE Scr , 3] A.
Current Electricity Index: 1. Any medium having practically free electric charges , free to migrate is a conductor of electricity. The electric charge flows from higher potential energy state to lower potential energy state. Positive charge flows from higher to lower potential and negative charge flows from lower to higher.
Metals such as gold, silver, copper, aluminium etc. When a potential difference is applied across a conductor the charge carriers electrons in case of metallic conductors flow in a definite direction which constitutes a net current in it. These electrons are not accelerated by electric field in the conductor produced by potential difference across the conductor. They move with a constant drift velocity. The direction of current is along the flow of positive charge or opposite to flow of negative charge.
In a current carrying conductor we can define a vector which gives the direction as current per unit normal, cross sectional area. The unit of potential difference is volt. Electrical resistance depends on the size, geometery, temperature and internal structure of the conductor.
It is also known as specific resistance of the material. Here we assume that the dimensions of resistance does not change with temperature if expansion coefficient of material is considerable. It says that the current through the cross section or the conductor is proportional to the applied potential difference under the given physical condition.
II - Law Loop analysis :The algebric sum of all the voltages in closed circuit is zero. The closed loop can be traversed in any direction.
Boxes may contain resistor or battery or any other element linear or non-linear. The current through each resistor is same. The effective resistance appearing across the battery. The voltage across a resistor is proportional to the resistance. Let r be the internal resistance of each cell. This maintains a uniform potential gradient along the length of the wire. Any potential difference which is less then the potential difference maintained across the potentiometer wire can be measured using this.
A shunt small resistance is connected in parallel with. It is used to measure potential difference. Then all other potential are measured with respect to this point. This point is also called the common point. If the current enters the higher potential point of the device then power is consumed by it i. If the current enters the lower potential point then the device supplies power i.
This energy is converted into heat. V2 t Joule. I 2 RT Calories. The figure denotes resistances in ohms. Find the equivalent resistance between A and D. In the circuit shown in figure potential difference between point A and B is 16 V. If a cell of constant E. Find the effective resistance of the network see figure between the points A and B. Where R is the resistance of each part. In the circuit shown in figure, all wires have equal resistance r.
Find the equivalent resistance between A and B. In the circuit shown in figure the reading of ammeter is the same with both switches open as with both closed. Then find the resistance R. Find the equivalent resistance between points A and B. If a galvanometer shows no deflection at the point P, find the distance of point P from the point a. If the galvanometer shows zero deflection at the position C, then find the value of unknown resistance R. Then find the resistance R Q.
The appropriate terminals of a cell of emf 1. What length of the wire will be required to produce zero deflection of the galvanometer? The meter deflects full scale for a current of 10 mA. The meter behaves as an ammeter of three different ranges. Calculate the resistance R1, R2 and R3. Find the maximum resistance of the network between points A and the point of sliding wire with BC. Calculate the current. What will be the change in the resistance of a circuit consisting of five identical conductors if two similar conductors are added as shown by the dashed line in figure.
The rod is connected in series with a resistance to a 6V battery of negligible internal resistance. What value should the series resistance have so that : the current in the circuit is 0. A piece of resistive wire is made up into two squares with a common side of length 10 cm.
A currant enters the rectangular system at one of the corners and leaves at the diagonally opposite corners. What length of wire connected between input and output terminals would have an equivalent effect. The potential at the points 1, 2, 3,..
A hemisphere network of radius a is made by using a conducting wire of resistance per unit length r. Find the equivalent resistance across OP. Three equal resistance each of R ohm are connected as shown in figure. A battery of 2 volts of internal resistance 0. Calculate R for which the heat generated in the circuit is maximum. A person decides to use his bath tub water to generate electric power to run a 40 watt bulb. If we install a water driven wheel generator on the ground, at what rate should the water drain from the bath tube to light bulb?
How long can we keep the bulb on, if the bath tub was full initially. The circuit shown in figure is made of a homogeneous wire of uniform cross-section. Eine Werbeplattform um mit Anzeigen interessierte Nutzer zu erreichen. Select your Schmalz subsidiary in one of the following countries :. Schmalz maintains an international sales network with sales partners in more than 80 countries.
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Greiferbaukasten PXT. Flexibilisierung von CNC-Bearbeitungszentren. Aufspannsysteme Matrixplatte. O, Konni, Pathanamthitta- Shubham Soni. Eman Khan. Chandru Chandru. Show More. Views Total views. Actions Shares. No notes for slide. Food and nutrition General Concept 1. The body utilizes these nutrients to grow and keep healthy and strong. To promote the physical and mental growth and development of human beings 2.
Building and repairing of tissues and cell damaged by infection and injuries. To provide energy for doing works. To protect the human beings from infections and deficiency disorders. Foods by sources: 1.
Cereals and 2. Fats and oils, 7. Nuts and oil seeds, 8. Sugar and jiggery 9. Condiments and species Others 10 Functions: energy production in the body; Useful in oxidation of fat, growth of useful bacteria, synthesis of vitamin B complex, absorption of minerals, prevention of constipation.
Animal sources: Milk, eggs, meat, fish, cheese etc. Plant sources: Pulses, cereals, beans. And Facilitates in calcium deposition in the bones and teeth. Liver, egg yolk, butter, cheese and some species of fish.
Due to anti- neoplastic effect raises the concentration of high density lipids cholesterol. With Vitamin E, selenium plays the role of preventing destruction of lipids by oxidation. Maintains stability of cell membranes.
Food rich in polyunsaturated fatty acids are also rich in vitamin E. Two types Phylloquinone — K1 and Manaquinone - K2. Dark green leafy vegetables, Cabbage, Cauliflower, are richest source. Also found in liver and cow milk. It is a water soluble vitamin. In general, this requires that failure in a safety system having redundant paths should be repaired within the mean time to repair assumed in the hardware reliability calculations.
If this is not possible, then the procedure should be the same as for non-redundant paths as follows. On failure in the safety system with no redundant paths, either additional process monitoring should be provided to maintain adequate safety or the EUC should be shut down. Many of these are contained in the documents listed in Chapter 9.
Structured, in this context, implies clear partitioning of functions and a visible hierarchy of modules and their interconnection. Such use of subjective descriptions e. In addition for SIL 3 systems, previous experience is needed in a relevant application and for a period of at least two years with ten devices or, alternatively, some third party certification.
SIL 4 systems should be both proven in use, as mentioned above, and have third party certification. The coverage of these tests would need to be significantly increased for SIL 4 systems. Thus the degree of testing of input and output modules, sensors and actuators would be substantially increased. Again, however, these are subjective statements and standards such as IEC do not and cannot give totally prescriptive guidance.
Nevertheless some guidance is given concerning diagnostic coverage. It should be noted that the minimum configuration table given in Section 3. This includes temperature and temperature cycling, EMC electromagnetic compatibility , vibration, electrostatic etc.
There needs to be feedback on operator actions, particularly when these involve keyboards, in order to assist the operator in detecting mistakes. As an example of this, for SIL 1 and SIL 2, all input operator actions should be repeated whereas, for SIL 3 and SIL 4, significant and consistent validation checks should be made on the operator action before acceptance of the commands.
The design should take into account human capabilities and limitations of operators and maintenance staff. Human factors are addressed in Chapter 6. The following section together with Appendix 4 discusses how to measure diagnostic capability and SFF. Should it then be necessary to enhance the diagnostic coverage, these tables can be used as a guide to techniques. This safe failure fraction, for each safety function, needs to be estimated as shown in Appendix 4.
The higher the SFF percentage requirement the more onerous is the demonstration. The tables provide the SIL number for each safe failure fraction case.
Simplex infers no redundancy. At first this might seem a realistic range of safe fail fraction ranging from simple to comprehensive.
However, it is worth considering how the diagnostic part of each of these coverage levels might be established. There are two ways in which diagnostic coverage and safe failure fraction ratios can be assessed: 1. By test: where failures are simulated and the number of diagnosed failures, or those leading to a safe condition, are counted. By FMEA: where the circuit is examined to ascertain, for each potential component failure mode, whether it would be revealed by the diagnostic program or lead to a safe condition.
This is illustrated in Appendix 4. In both cases the cost and time become more significant. In order to take credit for diagnostic coverage, as described in the Standard i.
For the case of a continuous system then the auto-test interval plus the time to put the system into a safe state should be within the time it takes for a failure to propagate to the hazard.
It involves specifying the reliability model, the failure rates to be assumed, the component down times, diagnostic intervals and coverage. Techniques such as FMEA failure mode and effect analysis and fault tree analysis are involved and Chapters 6 and 7 briefly describe how to carry these out. The Standard refers to confidence levels in respect of failure rates and this will be dealt with later. In Chapter 1 we mentioned the anomaly concerning the allocation of the quantitative failure probability target to the random hardware failures alone.
There is yet another anomaly concerning judgement of whether the target is met. If the fully quantified approach described in Chapter 2 has been adopted then the failure target will be a PFD probability of failure on demand or a failure rate. The reliability prediction might suggest that the target is not met although still remaining within the limits of the SIL in question. The rule here is that since we have chosen to adopt a fully quantitative approach we should meet the target set paragraphs 7.
This is, of course, SIL 2. However, 52 Functional Safety 3. Once again there is no right or wrong answer to the dilemma. The Standard does not address it and, as in all such matters, the judgement of the responsible engineer is needed. Both approaches are admissible and, in any case, the accuracy of quantification is not very high see Chapter 7.
This is the type of testing which, for example, looks at the output responses to various combinations of inputs. This applies to all SILs. For SIL 3 and SIL 4 the tests should be extended to include test cases that combine critical logic requirements at operation boundaries. These procedures, and the safety system interface with personnel, should be designed to be user, and maintenance, friendly.
This applies to all SIL levels. There need to be records of the demand rate of the safety-related equipment, and furthermore failures also need to be recorded. These records should be Meeting IEC Part 2 53 periodically reviewed, to verify that the target safety integrity level was indeed appropriate and that it has been achieved.
This should include a study of the relationship between the safety-related system and the EUC. It is necessary to ensure that any remedial action or additional testing arising from earlier tests has been carried out.
This requirement applies to all SIL levels. This paragraph applies to all SILs. Although Part 2 does not specify this for the hardware the authors consider this to be good practice. The random hardware failures prediction and safe failure fraction demonstrations are, however, still required. The previous field experience should be in an application and environment, which is very similar to the intended use.
All failures experienced, whether due to hardware failures or systematic faults, should be recorded, along with total running hours. Paragraphs 7. In Part 7 Annex D there are a number of pieces of statistical theory which purport to be appropriate to establishing confidence for software failures.
The times for larger numbers of failures can be calculated accordingly i. The following Conformance Demonstration Template is suggested as a possible format based on the layout of this chapter.
The Standard, in Part 6, gives two examples of Part 3 assessments. It does not, however, provide these for the Part 2 requirements. Conformance Demonstration Template IEC Part 2 For embedded software designs, with new hardware design, the demonstration might involve a reprint of all the tables from the Standard.
The evidence for each item would then be entered in the right-hand column as in the simple tables below. The following tables might be considered adequate for relatively simple designs, particularly with existing platforms and simple low variability code as in the case of PLCs. General Paras 7. Description of overall novelty, complexity, SILs, rigour needed etc. Sections 4. Whereas the reliability prediction of hardware failures, as addressed in Section 3.
All that can be reasonably claimed is that, given the state of the art, we believe the measures specified are appropriate for the integrity level in question and that therefore the systematic failures will probably be similar to and not exceed the hardware failure rate of that SIL. The Annexes of Part 3 offer appropriate techniques, by SIL, in the form of tables followed by more detailed tables with cross-references.
This chapter attempts to provide a simple and usable interpretation. Chapter 5, using the restricted subset of IEC , also caters for the Type 2 case. Progressive testing of the system starts with the lowest level of software module, followed by integrating modules, and working up to testing the complete safety system. Normally, a level of testing for each level of design would be required.
The life-cycle should be described in writing as well as graphical figures such as are shown in Figures 4. System and hardware interfaces should be addressed and it should reflect the architectural design. At SIL 2 and above there needs to be evidence of positive justifications and reviews of departures from the life-cycle activities listed in the Standard.
Figures 4. Beneath each of the figures is a statement describing how they meet the activities specified in the Standard. Figure 4.
The life-cycle model in Figure 4. Integration is a part of the functional test and validation is achieved by means of acceptance test and other activities listed in the Quality and Safety Plan. Validation is achieved by Requirements specification Quality and Safety plan Acceptance tests Functional specification Sub-system specifications Reviews Integration tests Module descriptions Functional tests Reviews Source code C and assembler maybe Static analysis semantic Figure 4.
The specification should extend down to the configuration control level. The document should be free from ambiguity and clear to those for whom it is intended. For SIL 1 and SIL 2 systems, this specification should use semiformal methods to describe the critical parts of the requirement e. For SIL 3 and SIL 4, semiformal methods should be used for all the requirements and, in addition, at SIL 4 there should be the use of computer support tools for the critical parts e. In the event of detecting an error or fault the system should, if appropriate, be allowed to continue but with the faulty redundant element or complete part of the system isolated.
Semi-formal methods should be applied, together with design and coding standards including structured programming, suitable for the application. This is called for from SIL 2 upwards. There should also be limited use of interrupts, pointers, and recursion.
Meeting IEC Part 3 4. At SIL 2 and above, dynamic objects and unconditional branches should be forbidden. At SIL 3 and SIL 4 more rigorous rules should be considered such as the limiting of interrupts and pointers, and the use of diverse functions to protect against errors which might arise from tools. Version numbers of modules and of test instructions should be clearly indicated.
Discrepancies from the anticipated results should be clearly visible. Any modifications or changes to the software, which are implemented after any phase of the testing, should be analysed to determine the full extent of retest that is required.
As an example, for SIL 1 and SIL 2 systems the testing should include boundary value testing and partitioning testing and in addition, for SIL 3 and SIL 4, tests generated from cause consequence analysis of certain critical events.
The Functional Safety Management requirements Chapter 2 should cover the requirements for both validation and verification. It should cover the entire lifecycle activities and will show audit points. At SILs 3 and 4 a more rigorous coverage of accuracy, consistency, conformance with standards e.
This paragraph applies for all SIL levels. The modification records should make it clear which documents have been changed and the nature of the change. There are packages available which carry out the procedures and, indeed, modern compilers frequently carry out some of the static analysis procedures such as data flow analysis. It should be remembered, however, that static analysis packages are only available for procedural high-level languages and require a translator that is language specific.
It is, however, not trivial and might well involve several mandays of analysis effort for a line segment of code. It is not referred to in the Standard. Static analysis, although powerful, is not a panacea for code quality. It only reflects the functionality in order for the analyst to review the code against the specification. Furthermore it is concerned only with logic and cannot address timing features. It is worth noting that, in Table B8, design review is treated as an element of static analysis.
The term formal methods is much used and much abused. In software engineering it covers a number of methodologies and techniques for specifying and designing systems, both non-programmable and programmable. These can be applied throughout the life-cycle including the specification stage and the software coding itself.
The term is often used to describe a range of mathematical notations and techniques applied to the rigorous definition of system requirements which can then be propagated into the subsequent design stages. The strength of formal methods is that they address the requirements at the beginning of the design cycle. One of the main benefits of this is that formalism applied at this early stage may lead to the prevention, or at least early detection, of incipient errors.
The cost of errors revealed at this stage is dramatically less than if they are allowed to persist until commissioning or even field use. This is because the longer they remain undetected the potentially more serious and far reaching are the changes required to correct them.
The potential benefits may be considerable but they cannot be realised without properly trained people and appropriate tools. Formal methods are not easy to use. As with all languages, it is easier to read a piece of specification than it is to write it. A further complication is the choice of method for a particular Meeting IEC Part 3 71 application. Unfortunately, there is not a universally suitable method for all situations.
Ladder Logic which is a limited variability language usually having no branching statements. These earlier languages are suitable for use at all SILs with only minor restrictions on the instruction set. Currently PLCs have wider instruction sets, involving branching instructions etc. With the advent of IEC there is a range of limited variability programming languages and the choice will be governed partly by the application. Again restricted subsets may be needed for safety-related applications.
Some application specific languages are now available, as, for example, the facility to program plant shutdown systems directly by means of Cause and Effect Diagrams. Inherently, this is a restricted sub-set created for safety-related applications. They are used in slightly different contexts but basically refer to the same concept of empirical evidence from use.
It is frequently assumed that the reuse of software, including specifications, algorithms and code will, since the item is proven, lead to fewer failures than if the software were developed anew. There are reasons for and against this assumption. The item has been subject to more than average test. The time saving can be used for more development or test. The item has been tested in real applications environments.
If the item has been designed for reuse it will be more likely to have stand-alone features such as less coupling. If the item has been designed for reuse it may contain facilities not required for a particular application therefore the item may not be ideal for the application and it may have to be modified.
Problems may arise from the internal operation of the item not being fully understood. In conclusion, provided that there is adequate control involving procedures to minimise the effects of the above then significant advantages can be gained by the reuse of software at all SILs. An obvious example would be the number of branching statements in other words a measure of complexity which might be assumed to relate to error rate. There has been interest in this activity for many years but there are conflicting opinions as to its value.
In the long term metrics, if collected extensively within a specific industry group or product application, might permit some correlation with field failure performance and safety-integrity.
The term metrics is also used to refer to statistics about test coverage, as called for in earlier paragraphs. It should also have satisfied suitable procedures, testing and verification for the SIL in question or have evidence to support its use from satisfactory previous use.
Also, the operating experience should have exercised all the safety-related functions associated with the module. In Part 3, Paragraphs 7. In Part 7 Annex D there are a number of pieces of statistical theory which purport to be appropriate to the confidence in software. Conformance Demonstration Template IEC Part 3 For embedded software designs, with new hardware design, the demonstration might involve a reprint of all the tables from the Standard. Feature SIL 2 and above Alternative life-cycle models to be justified Configuration control to level of smallest compiled unit Feature SIL 3 and above Alternative life-cycle models to be justified and at least as rigorous Sample review of configuration status Feature SIL 4 Alternative measures to the life-cycle to be separately reviewed Evidence Evidence Evidence Evidence Specification Para.
The standard was issued at the beginning of and is in three parts: Part 1 Part 2 Part 3 The normative standard Informative guidance on Part 1 Informative guidance on hazard and risk analysis Part 1 of the standard covers the life-cycle including: Management of Functional Safety Hazard and Risk Analysis Safety Instrumented Systems SIS Design through to SIS decommissioning The standard is intended for the activities of SIS system level designers, integrators and users in the process industry. Component level product suppliers, such as field devices and logic solvers, are referred back to IEC as is everyone in the case of SIL 4.
Part 2 gives general guidance to the use of Part 1 on a paragraph-by-paragraph basis. Part 3 gives more detailed guidance on targeting the Safety Integrity Levels and has a number of appendixes covering both quantitative and qualitative methods. Since the standard is only aiming at the integration level of the SIS, rather than the individual elements, the requirements Meeting IEC 81 for design and development of the SIS covered by Parts 2 and 3 of IEC have been significantly simplified.
The software requirements are restricted to the applications software using either limited variability languages or fixed programs. For applications software using full variability languages the user is referred to IEC Unless specifically identified the same techniques and measures will be used for SILs 1, 2 and 3.
Where a project involves the development and modification of a system architecture and application software for SIL 4, or the use of Full Variability Languages for applications software or the development of a sub-system product then IEC should be used.
Figure 5. The life-cycle is required to be included in the project Quality and Safety Plan. The assessment team should include at least one senior, competent person not involved in the project design. Part 1 of describes the typical layers of risk reduction namely Control and monitoring, Prevention, Mitigation, Plant emergency response and Community emergency response. Part 3 gives examples of numerical approaches, a number of risk graphs and LOPA as mentioned in Section 2.
Action taken on bad process variables e. The Standard gives guidance on the use of field devices and non-PE logic solvers for up to SIL 3 safety functions using proven-in-use justification. Unfortunately, both tables are formatted differently to the IEC table and assume type B sub-systems only i. At any time the table in IEC can be used see Chapter 3. For interest the version is shown below. The complete system shall be validated by inspection and testing that the installed system meets all the requirements, that adequate testing and records have been completed for each stage of the life-cycle and that any deviations have been adequately addressed and closed out.
As part of this system validation the application software validation, if applicable, needs to be closed out. Change proposals will be positively identified, by the Project Safety Authority, as safety related or non-safety related.
All safety-related change proposals will involve a design review, including an impact analysis, before approval. As a minimum the plan should include checking for completeness earthing, energy sources, instrument calibration, field devices Meeting IEC 89 operation, logic solver operation and all operational interfaces. Records of all the testing results shall be kept and any deviations evaluated by a competent person.
If there are any significant increases in hazard demand rate or decreases in the safety system availability between the design assumptions and those found in the operation of the plant which would compromise the plant safety targets then changes to the safety system will have to be made in order to maintain the plant safety. This model was not often seen in WA but offers the flexibility of a very capable rotto overnighter or even an offshore fishing trip.
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