Understanding SISTEMA

Transcription

1 Understanding SISTEMA Safety Integrity Software Tool for the Evaluation of Machine Applications Like any software tool, SISTEMA is only as useful as the information entered into it. That being said, using the tool can be a significant time-saver as opposed to doing the required calculations by hand. The process of obtaining the appropriate Performance Level calculations is non-trivial. Even with the SISTEMA tool, a strong understanding of the process is required. Inside Downloading the SISTEMA Tool Navigating the SISTEMA Interface SISTEMA Objects The SISTEMA Screen How to Use the SISTEMA Tool omron247.com 1

2 Downloading the SISTEMA Tool 1. Go to softwa/sistema/index.jsp 2. Click on the download link. 3. Enter your address and confirm it. 4. Click the button marked Submit. SC01 5. An will be sent to you with the download instructions. Click on the link to go to the download page. 6. Checking the box will add your name to the newsletter. This is optional. 7. Click the SISTEMA Download button. The downloaded file will be in a.zip format. SC02 8. Unzip the downloaded file and install the software. You will be prompted for a language. SC03 9. If you had a previously installed version, it will automatically un-install and install the new version. When the install is complete you will get a configuration box as shown. SC Accept the defaults and click OK. SISTEMA will launch. 2

3 Navigating the SISTEMA Interface It is important to understand the underlying concepts that drive the tool. Enter the relevant parameters: 1. Category 2. The average component quality (MTTFd) 3. The average test quality (DCavg) of components and blocks, and 4. Common-cause failures (CCFs) The Performance Level (PL) results are calculated and displayed instantly. SISTEMA Objects SISTEMA recognizes seven different types of objects. These can be regarded as the building blocks from which a project is created. Each object in the project can be selected in the Navigation pane and then configured in the workspace. Objects can in turn serve as containers for other objects. A single safety function for example can contain several subsystems. Project: The project file itself is treated as an object in SISTEMA. It generally refers to a machine or dangerous point which is analyzed. A project may contain any desired number of safety functions. Safety Function: A safety function is any function of the machine under analysis where the failure may lead to a direct increase in the risk. A safety function is implemented by one or more subsystem(s). Subsystem: A subsystem is a part of a control system which processes and generates safety-related signals. Several subsystems can be connected in a series arrangement for implementation of a safety function. A subsystem generally implements a designated architecture. In this case, the essential structure is determined by the number of channels and possibly by an item of test equipment (only in category 2). Channel: In SISTEMA, a subsystem may comprise one or two channels. A channel object represents a container for blocks, i.e. its purpose is solely that of structuring, and it permits the modeling of multi-channel architectures. The number of channels is determined by the selection of a Category for the higher-level subsystem and the associated designated architecture. Note: In Category 2 architectures, a test channel or item of test equipment has the function of repeated testing of whether the function of the functional channel is being executed properly. Like the channel, the test channel forms part of a subsystem. A subsystem may possess no more than one test channel. Block: A function block is the context of a logical block diagram. It divides a channel into logical functional units (i.e. sensor, logic, main contactor). A channel should always contain at least one block. In SISTEMA, it may be possible for a block to be modeled in even greater detail by the listing of its component elements. 3

4 Element: An element constitutes the lowest hierarchical level of the objects types. Elements are electronic, electromechanical, hydraulic, mechanical or pneumatic components from which a function block is composed. The diagram below shows the relationship of the various SISTEMA objects. SC05 The SISTEMA Screen Contextual help is available on the right hand navigation panel. SC06 4

5 SISTEMA has performance data installed in a library based on the generic values defined in the ISO standard. Many manufacturers, including OMRON, have created SISTEMA libraries with their specific product performance data. Links to all the available libraries can be found at sistema/bibliotheken/index.jsp To load a library into SISTEMA. you must first download the library and save it. OMRON has multiple libraries. The OMRON libraries can be found at: After saving the library, simply click on the library button at the top of the SISTEMA tool. Click the Add local library button. SC07 Select the location of the desired library and click OK. The library will be added to the SISTEMA tool. Repeat for each desired library. SC08 Click Close to return to the main screen. 5

6 How to Use the SISTEMA Tool Before using the SISTEMA tool, the safety functions must be clearly defined. It is highly recommended that the system designer create a block diagram of the system elements before starting the SISTEMA evaluation. To use the SISTEMA tool: 1. Create a project (PR) and define one or more safety functions (SF) 2. Determine the required PLr by the risk graph (or direct input) 3. Define one/several sub-systems (SB) and select their category 4. For each sub-system: Input the vendors reliability values (PL, PFH, Category) Paste data from supplied libraries or Define blocks (BL) and subordinate elements (EL) Input of all relating reliability data (MTTFd, DC, B10d, CCF, and so on) 5. Compare the achieved PL with the required PLr 6. Save project with check sum, printout/pdf by report function If an adequate risk assessment has already determined the appropriate PLr, enter that value in step 2. It is highly recommended that the Risk Assessment be based on the manufacturer s accepted practice. In general, the risk assessment tool included in SISTEMA is only a guide, and is not comprehensive. Example: For instructional purposes only, the following example demonstrates how to use the SISTEMA tool for a simple safety system. The safety system in this case consists of a safety light curtain, an OMRON G9SX-BC, and 2 contactors with mirrored contacts for monitoring (while the use of the G9SX-BC is not required for use with a modern light curtain, we have added it here for the purpose of demonstration.) SC09 6

7 Before turning to the SISTEMA tool, let us assume we have completed a risk assessment and determined we need a PLr of d. We also need to understand the functional block diagram of our proposed design. The diagram below shows how the different elements might be constructed in a block diagram. This simple system has three sub-systems corresponding to Input, Logic, and Output. SC10 Now let s start entering data into SISTEMA. First we create a new project by clicking on the New Button and then clicking on the PR in the left hand navigation window. SC11 Note the Yellow warning box. SISTEMA will provide you with instructions as you proceed. Enter a name for the project and provide any additional information. Next Define the safety function by selecting the safety function tab and clicking New. SC12 7

8 Open the new safety function by double clicking on it. Provide a name. Select a type of safety function from the drop down list and supply any additional information. SC13 Next select the PLr tab. Since we already have competed our risk assessment and know our PLr, we select the Enter PLr value directly radio button and select the value from the drop down box. SC14 Click on the subsystems tab. The first subsystem we defined was the F3SJ Light curtain. After naming this subsystem click the PL tab. Since we are able to determine the PL for this device from the OMRON documentation, select the enter PL/PFH directly radio button and enter the data. *The F3SJ data sheet states the Pl for this device is e. SC15, SC16 Next return to the safety function tab and create the next Subsystem. For this subsystem we can use the data from the OMRON library, Click the Library link to select the G9SX-BC. SC17 Select the G9SX-BC by clicking on it and then select the Load. (Load and close in this case since this is the only item we are taking from the library.) SC18 8

9 This loads all the required information for this subsystem into the tool. Now we must add the last subsystem. Open the safety function subsystem tab. Click New, and provide a name. This subsystem is the output block. The data for the contactors must be calculated so we need to select the Determine PL/PFH from Category, MTTFd and DCavg button. Open the Category tab. Complete the check boxes for this subsystem. SC19 Click the MTTFd tab. Since contactors do not have a stated MTTFd because their life is based on the number of cycles they go through, select the Determine MTTFd from blocks radio button. SC20 Select the Blocks tab. Double click on the <unknown block> to open the block. Provide a name and select the MTTFd tab and select Determine MTTFd from the elements. (SC21) 9

10 Select the Blocks tab and similarly provide a name. Open the MTTFd tab and select determine the MTTFd from the B10d value. Since we don t know the exact B10d values for these contactors we must use the generic data available from the standard. SISTEMA makes this easy by clicking the typical components value button. SC22 Since we have properly sized our contactors, we can select the small load option and click OK which will load the value into SISTEMA. SC23 Next we need to provide the cycle and life parameters of the machine. Click on the Calculate nop button to add the required data. d_op = number of days per year the machine is expected to operate. h_op = number of hours per day t_cycle = cycle time of the machine 10

11 The Machine Life is preselected for 20 years, modify this value if necessary. Click OK. SC24 The calculated MTTFd for this element is Medium. Select the DCavg tab. Click the select applied measures to evaluate DC. Then click the Library button. SC25 11

12 Select the appropriate description from the Library. In this case, direct monitoring. Click the Load Selection button. Since Channel two in this case is identical to channel one, complete the information for channel two in the same manner. Finally return to the Contactor subsystem and select the CCF tab. Experienced designers may enter the CCF values directly, otherwise select the Select applied measure to evaluate CCF, and click the Library button. Note: The CCF determination requires an in-depth understanding of the design parameters and must be chosen by an experienced engineer. Review and select each of the CCF elements that are appropriate for the system. The CCF value must be greater than 65 for the design to be valid. Each selection must be loaded until the final value is reached and the system indicates this parameter has been fulfilled. SC26 12

13 For this example, we have defined only a single safety function. If multiple safety functions are required, they would be added and the subsystems, elements, etc. would be defined in a similar manner. When all the safety functions are complete the SISTEMA tool indicates the PL for each. For our example, it shows that the PL for this system is d and since that is equal to our PLr the system verification is complete. The file should now be saved and kept as part of the technical file. SC27 The use of the SISTEMA tool is not a substitute for safety system design. It enables the designer to model the structure of the safety-related control components based upon the designated architectures. A practical advantage for the user is that any parameter change is reflected immediately on the user interface with its impact upon the entire system. This enables one to play with parameter values and thus to assess the global effect of modifications with a minimum of effort. The final results can be printed out in a report. Disclaimer: Use of the software is at the user s own risk. To the extent permissible by law, no liability will be accepted for the software on any legal basis. In particular, no liability will be accepted for material defects or defects in title, whether in the software or in the associated documentation and information, particularly with regard to their correctness, freedom from errors, freedom from property rights and copyright of third parties, up-to-dateness, completeness and/or fitness for purpose, except in cases of malicious or wrongful intent. OMRON provides this data for demonstration purposes only and does not warrant the validity of the data or assumptions presented. 13

14 Would you like to know more? Omron Automation and Safety omron247.com Stay in touch twitter.com/omronproducts youtube.com/user/omronautomationtech linkedin.com/company/omron-electronics OMRON AUTOMATION AND SAFETY Americas Headquarters Chicago, IL USA industrial.omron.us OMRON CANADA, INC. HEAD OFFICE OMRON ARGENTINA HEAD OFFICE Toronto, ON, Canada industrial.omron.ca Cono Sur OMRON ELECTRONICS DE MEXICO HEAD OFFICE OMRON CHILE SALES OFFICE México DF industrial.omron.mx Santiago OMRON ELECTRONICS DE MEXICO SALES OFFICE OTHER OMRON LATIN AMERICA SALES Apodaca, N.L industrial.omron.mx OMRON ELETRONICA DO BRASIL LTDA HEAD OFFICE São Paulo, SP, Brasil omron.com.br OMRON EUROPE B.V. Wegalaan 67-69, NL-2132 JD, Hoofddorp, The Netherlands +31 (0) industrial.omron.eu S42I-E-01 Note: Specifications are subject to change 2015 Omron Electronics LLC Printed in U.S.A