Safety Systems Safety Integrated

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1 Why do you want to use machine safety products? Are you a global supplier? Are you aware of the achinery Directive? The achinery Directive was implemented in 1993 in the European market to harmonize the national standards and regulations of all of the European Communities. The definition of a machine according to the achinery Directive is: "achinery also means an assembly of machines which, in order to achieve the same end, are arranged and controlled so that they function as an integral whole." Basically, the achinery Directive defines the objectives of machine design in terms of the basic health and safety requirements mandatory for the safety of new machines so that they may be sold within the European Union. The manufacturer of a machine must prove that the basic requirements are fulfilled. The CE mark is the only marking which certifies that the industrial product conforms to the EU machinery directive. (See Figure 1.) The key requirements of the EU are: A file must be established containing the technical construction of the machine. The machinery s compliance must be certified with the technical requirements. An instruction manual must be provided with each machine. To obtain the requirements for the CE mark, the achinery Directive describes the steps for the machine builder. Siemens SIRIUS safety devices have been specifically designed to meet and exceed the stringent safety requirements mandated by the European achinery Directive 98/37/ EC for machine safety. (For further explanation of the achinery Directive and Standards, reference the SIE- ENS Safety Integrated Application anual). The European Standards of CENa for the safety of machines are hierarchically structured as follows: What are the main CE-Standards according to achine Safety? Type A Standards: Fundamental safety standards giving basic terminology and general design principles that can be applied to all machines. Type B Standards: Group safety standards dealing with one aspect or one type of safety related device that can be used across a wide range of machinery. Type B Standards are divided into higher level aspects (B1-Standards) and safety devices (B2-Standards). Type C Standards: Requirements regarding to a specific group of machinery Type C Standards often include requirements which, under certain circumstances, deviate from the Basic- and Group Standards. For the machine OE, type C Standards have the highest priority. CEN: European Committee for Standardization Self-operative machine referred to in no Annex IV 98/37/EC yes fr. documentation (self- certification ) acc. to Annex V no eet harmonized EN-Standards? yes Certification optional Verification (by notified body) or certification Declaration of conformity / CE-ark Figure 1: Evaluation Process for Obtaining the CE ark 13/6

2 Type A standards EN 292 Basic principles, general design principles EN 1050 Risk assessment EN 414 Rules for elaboration and presentation of safety standards Type B1 standards Type B2 standards EN EN 954 achines-electrical equipment Safety related parts of control systems IEC/EN Electrosensitive protective equipment general requirements EN 294 Safety distances to prevent upper limbs from reaching danger zones IEC/pr EN Electrosensitive protective equipment-ac tive optoelectronic area protective devices pr EN 811 Safety distances to prevent lower limbs from reaching danger zones EN 1760 EN 1088 Pressure-sensitive protective devices Locking and interlocking devices pr EN 999 Hand/arm speed approach speeds of parts of the human body for positioning protective devices EN 418 EN 574 IEC/EN Emergency stopping equipment Two-hand controls Electromechanical control circuit devices Type C standards Cold working of metals pr EN 692 echanical presses pr En 693 Hydraulic presses achines for plastic and rubber pr EN 201 Injection presses, injection moulding machines pr EN 289 Compression and transfer presses pr EN 1114 Extrusion machines and extrusion lines pr EN 1417 Two-cylinder mixers pr EN 422 ould blowing machines Packaging machines pr EN achines for pre-formed rigid packaging pr EN Form, fill and seal machines pr EN Palletizers, depalletizers pr EN Wrapping machines pr EN achines to form collective packaging pr EN achines to ensure cohesion of load units Graphic and paper machines pr EN 1010 Graphic machines pr EN 1034 Paper machines achines for wood pr EN 691 pr EN 859 pr EN 860 pr EN 861 pr EN 1807 pr EN 848 pr En 940 pr EN 1218 Tanning machines pr EN 972 pr EN 1035 pr EN 930 pr EN 931 iscellaneous pr EN EN 775 pr EN 1525 Common requirements Surfacing machines with manual feed One-side planing machines Surfacing and planing combined machines Bandsaws illing machines with spindle Combined machines Tenoning machines Reciprocating machine with roller achines with mobile tables Carding, sandpapering, polishing and milling machines Assembling, folding, nailing machines Safety of laser machines for treatment of materials Safety of manipulating robots Industrial trucks without drivers and their systems 13/7

3 Are your customers requiring safety designs for their machines? Have you been asked or required to implement safety in the design of new machines? With an increased concern for personnel safety and required legal standards, incorporating safety has become a priority in the US market. There are many organizations that affect safety in the US. Two such bodies overseeing the "control reliability" of machinery in the United States are the American National Standards Institute (ANSI) and the Occupational Safety and Health Administration (OSHA). ANSI is an association of industry representatives who, working together, develop safety and technical standards. OSHA is a government agency responsible for monitoring and regulating workplace safety. ANSI and OSHA have provided the following definitions for control reliability: "Control reliability" means that when a component, module, device or system failure occurs, such that it or a subsequent failure of another component, module, device or system would lead to the inability of the safetyrelated function(s) to respond to a normal stop command or an immediate stop command, the safety-related function shall: Prevent initiation of hazardous machine motion (or situation) until the failure is corrected or until the control system is manually reset; or, Initiate an immediate stop command and prevent re-initiation of hazardous machine motion (or situation) until the failure is corrected or until the control system is manually reset; or, Prevent re-initiation of hazardous machine motion (or situation) at the next normal stop command until the failure is corrected or until the control system is manually reset. (ANSI B , 6.1) "The control system shall be constructed so that a failure within the system does not prevent the normal stopping action from being applied to the press when required but does prevent initiation of a successive stroke until the failure is corrected. The failure shall be detectable by a simple test, or indicated by a control system." (OSHA 29 CFR ) OSHA regulations and definitions for machine safety can be found in OSHA ANSI standards for machine safety can be found in ANSI B11 series. Where is safety used today? Automotive Industry Pulp, Paper, and Paperboard ills Packaging and Wrapping Industry achine Tooling olding and Power Presses Robotic Work Cells Automated Production Equipment Pipe, Tube and Shape Bending achines Gear Cutting achines etal Sawing achines Assembly Lines ost common applications for safeguarding machines: Emergency-STOP Circuit Protected Doors or Gates Sliding Edges Access Protection Perimeter Protection Two-Hand Control 13/8

4 Is increased safety for your personnel and equipment a priority? As a result of their general design and functionality, machine and plants represent potential risks. Risk assessment is a sequence of steps which allows hazards caused by machines to be systematically investigated. Risk is a function of the severity of possible harm for the considered hazard and the probability of occurrence of that harm. The following Standards may be applied to assess risks: EN 292 "Safety of machinery Basic concepts, general principles for design." This standard mainly handles the risks to be evaluated and design principle to reduce risks. EN 1050 "Safety of machinery Principle for risk assessment." This standard basically handles the iterative process with risk assessment and risk reduction to achieve safety. EN 954 "Safety related parts of control systems." This standard provides the safety requirements and guidance for the design of the safety related parts of control systems. It gives guidance on the specification, design process and validation including the selection of categories as reference points. After following the risk assessment process (see Figure 2), a risk category or level of risk can be assigned. The requirements of the safety related parts of the control system are then determined from the risk category. Risk Assessment in America for machine tools is covered by the ANSI B11 TR3 part of the ANSI B11 series of technical reports and standards pertaining to the design, construction, care and use of machine tools. The ANSI B11 TR3 report defines a method of conducting a risk assessment and risk reduction for machine tools, provides some guidance in the selection of appropriate protective measures (safeguarding) to achieve tolerable risk, and describes the risk assessment and risk reduction responsibilities of both the machine tool supplier and user. Risk Assessment in America for robotic applications is covered by the ANSI / RIA (Please refer to the SIEENS Safety Integrated Application Handbook for further information regarding Risk Assessment). S1 (slight, normally reversible injury) S2 (severe, normally irreversible injury including death) F1 (seldom) F2 (frequent to continous) P1 (possible) P2 (scarcely possible) P1 (possible) P2 (scarcely possible) S - Severity of the injury F - Frequency and /or exposure time to the hazardous condition P - Possibility of avoiding the hazard Categories for safety related parts of control systems : Preferred categories for reference points : Possible categories requiring further steps : easures which can be overdimensioned for the relevant risk Figure 2: Risk Assessment Acc. to EN /9

5 What makes a system safe? any components make up a safety system. A safety device may consist of a sensor or switch, which initiates the "safety condition." Switches or sensors used in safety circuits are control devices with high reliability. They interrupt the control circuit of the machine in order to create a safe condiiton. Devices with "direct opening action" contacts are specified in circuits where the safety of machine operators and equipment depend on the opening of one or more contacts when actuated in safety situations. Devices meeting these requirements are marked with the symbol shown below and must be installed in circuits protected by a short-circuit protective device specified by the manufacturer. This will avoid welding of the contact in case of a fault condition. Devices with "direct opening action" contacts: Emergency-Stop Pushbuttons Limit Switches, All Types Rope-Pull Switches Foot Switches The term, positive opening operation, was previously used in the IEC and EN standard, but is now replaced by the term "direct opening action." Redundancy is incorporated in the safety circuit to ensure safety functionality even if a failure disables one channel. A safety relay unit performs fault detection and evaluation. It opens the circuit when it detects a failure. The feedback loop monitors the correct operation of the output device. In some safety circuits, a start sensor or switch is incorporated to reactivate the safety circuit. See example of the functionality of a safety circuit below. (See Figure 3.) The overall safety category depends on the components used in the safety circuit as well as on the wiring and installation. Beside the relay units, sensors and contactors also may affect the overall safety category required for the whole circuit. "Positive opening action" or "mechanical linked contacts" are requirements which are essential for machine safety products. Command devices as well as our SIRIUS contactors meet these requirements and can be used in any safety circuit up to Cat.4, acc. to EN For correct wiring examples and usage of the components please refer to the wiring examples and the proper product instruction sheet. Symbol for Direct Opening Action: Figure 3: Principle of a Safety Circuit 13/10

6 What is a Category and which impact does it have on the circuitry? Category acc. to EN954-1 is a terminology very often used to express the requirements for a particular safety level. EN954-1 divides the safety levels into 5 Categories (B, 1, 2, 3 and 4) with B being the lowest and 4 the highest level. All parts and devices, from the origin of the command ultimately down to the lockout or stop of the machine, have to at least meet the requirements of the selected Category. With the increase of the Category, the degree of the failure detection rises. That entails additional effort in product functionality as well as in wiring. The following table should give a brief overview of the requirements of each Category: For safety circuits from Category 3 and higher, EN954-1 requires a redundant structure to avoid the loss of the safety function in case of a failure. This requirement of single fault detection does not mean that all faults will be detected. The accumulation of undetected faults still may lead to an unintended output signal. For Category 4 any single fault should be detected and will not lead to the loss of the safety function. To meet the requirements acc. to EN954-1 redundancy shall affect every component of the safety circuit. Two contactors or even two interlocking switches, wired in series, should be used and connected to the safety relay unit. For Category 4 in addition one NC auxiliary contact from each of the two contactors should be integrated in the feedback loop. Without both of these NC contacts wired in series in the feedback loop, the safety circuit is reduced to a maximum Category 3 level. The two NC safety contacts for a Emergency-STOP pushbutton should be seperated within two contact blocks If manual restart is used the device should be monitored from the safety relay unit. Table 1: Categories Acc. to EN954-1 Categories EN Consequences of faults Requirements of the control system Circuitry examples (not contractual) Techniques for circuitry examples B Possibility of loss of safety function after a single fault Equipment designed according to basic principles intended to ensure reliability Conventional relays 1 Possibility of loss of safety function after a single fault Design based on well established components and principles mechanically linked contacts (direct opening; reliabilbility) t 2 Possibility of loss of safety function if a fault appears between 2 test circle The integrity of the safety function is based upon a periodic test. A failure should be detected at the following test circle on cyclical test 3 Safety function maintained in case of a single fault. Accumulation of undetected and non-dangerous faults may lead to the loss of the safety function + - on K2 redundancy (dual channel) 4 Safety function maintained in case of multiple faults Same as Category 3, but accumulation of undetected faults never leads to the loss of the safety function K2 on K2 redundancy; feedback loop; cross fault detection 13/11

7 What is the advantage in using SIRIUS in the complete safety application? achine Safety, not only because of the existing regulations, is a need in today s world of total automation. Very often, achine Safety is considered a separate application serviced only by specially trained personnel with detailed knowledge. Siemens, as a worldwide solution provider, offers a complete range of standard control products. Safety Integrated, achine Safety will be integrated within the standard automation process. Siemens strengths include: Worldwide Certifications Complete Product Lines Global Support and Service Technical Leadership International Experience Within our Siemens Safety Integrated product range we will provide the link between standard automation and machine safety. When setting up a machine design, the potential risk should be determined and reduced to a tolerable level. The particular risk level, called "Category" in the EN954-1 Standard, always refers to the whole safety circuitry of the special part of the machine. This includes safety related Sensors, Command Devices, Evaluation Units and Contactors. One single product can not meet the intended safety level and does not solve the problem. Only the combination of correct risk determination, mechanical protection equipment, failsafe evaluation, correct wiring and reliable devices will provide the required solution. (See Figure 4.) Safety Integrated products encompass: a wide variety of applications all levels of machine safety latest requirements in standardization electromechanical and optical sensors complete line of safety relays wiring and application examples contactors and circuit breakers designed for machine safety applications and will help your company shape a safer, more productive workplace by integrating machine safety into standard automation processes. Figure 4: Complete Safety Circuit 13/12