Functional Safety Shealy Energy Expo
November 6 Mark Madden Product Manager – Safety Detection, Pressure, and Mechanical Sensors 1
Agenda Introduction Safety Standards Risk Assessment Inputs Logic
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Invest in safety– WHY ?
> Health & safety for all personnel health & safety for all personnel > Cut costs associated with: > Physical injuries > Insurance premiums > Lost production, penalties
> Increased productivity due to the prevention of accidents > Better failure detection > Higher worker confidences at work > Improving maintenance efficiency Confidential Property of Schneider Electric
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Why we need strong International Machine Safety Rules
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Standards
> A few of the most important US Standards are: > OSHA 29 CFR1910 > NFPA 79, Electrical Standard for Industrial Machinery > ANSI B11.19, Performance Criteria for Safeguarding > ANSI/RIA R15.06, Industrial Robots and Robot Systems, Safety Requirements
> Locally > UL and CSA (in Canada) > UL is mandatory in most US cities in their codes and requirements. > Customers and users demand these approvals even if local codes do not require it.
> Canada > CSA is mandatory in Canada
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US Standards Organizations
> Occupational Safety and Health Administration (OSHA) > American National Standards Institute (ANSI) > National Fire Prevention Association (NFPA) > Underwriters Laboratories Inc. (UL) > Factory Mutual Research Corporation (FM) > National Electrical Manufacturers Association (NEMA)
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Occupational Safety and Health Act of 1970
> SEC. 5. Duties(a) Each employer > (1) shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees; (2) shall comply with occupational safety and health standards promulgated under this Act.
> “The compliance with OSHA regulations is the responsibility of the employer (user), not the seller of equipment”. > SEC. 6. Agencies. “organizations which are not agencies of the U.S. > Government which are incorporated by reference in this part, have the same force and effect as other standards in this part” Confidential Property of Schneider Electric
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Many Standardization Institutes IEC (electrical standards) ISO (other standards: mechanical parts)
CEN (mechanical standards) CENELEC (electrical standards) CSA ANSI UL
SIS BS NF DIN UNE CEI
GOST JIS
OSHA
(PCB making machines)
SAA
ISO: International Organization for Standardization IEC: International Electrotechnical Commission CEN: Comité Européen de Normalisation CENELEC: Comité Européen de Normalisation Electrotechnique Confidential Property of Schneider Electric
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Many Standardization Bodies All countries use IEC and ISO or adapt them locally. All the institutes work jointly with other international organizations
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A, B, C Standards 1. The functions that are regulated by type B2 standards, and served by dedicated safety products
2. The functions that are specific to one type of machine, and derived from the requirements of type C standards. Those safety functions are solved by machine builders with specific mechanical and automation design > A: Basic Standards (e.g risk assessment & reduction) > B: Generic Standards > B1: Particular Safety aspects (e.g safety distance) > B2: Safeguards (e.g interlocking devices) 10 > C: Standards for particular machines Confidential Property of Schneider Electric
Safety - Acceptable Risk Level
> Zero Risk does not exist but risk must be reduced to an acceptable level > Safety is the absence of risks which could cause serve injury or damage the health of persons. > It’s the machine designer job to reduce all risks to a value lower than the acceptable risk.
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Risk Reduction
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Func%onal Safety PL & SIL
Sector specific standards for the Process Industry and Machinery
Safety of Systems and Equipment
IEC/EN 61508
EN 954-‐1
Func%onal safety of electrical / electronic / programmable electronic safety-‐related systems
Safety related parts of control systems
Machines
Process
SoKware
IEC/EN 61511
IEC/EN 61508-‐3
IEC/EN 62061
Standards highlighted in red are Interna%onal standards
EN/ISO 13849-‐1
New Machinery Directive > EN ISO 13849-1:2006 Machinery safety – safety related parts of control system non electrical and simple electrical > This standard is an evolution of EN 954-1 and provides safety requirements and guiding principles for design and integration of safety-related parts of control system; e.g. electrical, mechanical, pneumatic and hydraulics technologies > EN IEC 62061:2003 Machine safety – functional safety of electrical, electronic and programmable electronic control systems. > This is a machinery sector standard based on IEC 61508 primarily for electrical, electronic and programmable electronic systems. Confidential Property of Schneider Electric
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En/IEC 62061, EN/ISO 13849-1 > Both EN/IEC 62061 and EN/ISO 13849-1 and 2 specify requirements for the design and implementation of safety-related control systems of machinery. The methods developed in both of these standards are different but, when correctly applied, can achieve the same risk reductions. > These standards classify safety-related control systems that implement safety functions into levels that are defined in terms of their probability of dangerous failure per hour (PFHd). > EN/ISO 13849-1 has five Performance Levels (PLs): a, b, c, d and e > EN/IEC 62061 has three Safety Integrity Levels (SILs): 1, 2, and 3. > Machinery designers can choose to use either EN/IEC 62061 or EN/ISO13849-1 or a combination of both.
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Key Points – Control Reliability > Both
OSHA and ANSI refer to a term “control reliability”. > Control reliability described per ANSI B11.19 - Performance Criteria for Safeguarding: “When required by the performance requirements of safeguarding, the device, system or interface shall be designed, constructed and installed such that a single component failure within the device, interface or system shall not prevent normal stopping action from taking place but shall prevent a successive machine cycle. This requirement does not apply to those components whose function does not affect the safe operation of the machine tool.” OSHA has similar wording. > To accomplish this, some sort of redundancy is needed to carry out the stop command if there is a failure of one of the components Confidential Property of Schneider Electric
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Basic Safety Idea
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Appendix 2: Category, structure and behavior! Category B
When a fault occurs it can lead to the loss of the safety function
Input
Category 1
When a fault occurs it can lead to the loss of the safety function, but the MTTFd of each channel in category 1 is higher than in category B. Consequently the loss of the safety function is less likely.
Input
Category 2
Category 2 system behavior allows that: the occurrence of a fault it can lead to the loss of the safety function between the checks; the loss of the safety function is detected by the check.
Input
im
im
im
im
Logic
Logic
Logic
Test equipment
Category 3
Category 4
SRP/CS to category 3 shall be designed so that a single fault in any of these safetyrelated parts does not lead to the loss of the safety function. Whenever reasonably possible the single fault shall be detected at or before the next demand upon the safety function.
Input 1
SRP/CS to category 4 shall be designed so that a single fault in any of these safetyrelated parts does not lead to the loss of the safety function, and the single fault is detected at or before the next demand upon the safety functions, e.g. immediately, at switch on, at end of a machine operation cycle. If this detection is not possible an accumulation of undetected faults shall not lead to the loss of the safety function.
Input 1
! From EN/ISO 13849-1 Section 6.2 – Specifications of Categories
im
Logic 1 cross
Input 2
im
im
Logic 2
Input 2
im
im
Output
Test output
Output 1
m im
Output 2
monitoring
Logic 2
Output
m im
Logic 1 cross
im
monitoring
im
Output
m im
Output 1
m im
Output 2
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5 Pillars of Safety Control system
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Message from our sponsor Use of suitable materials Well-tried safety principles Well-tried component Prevent Common Cause Failures 20
Common types of danger
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Machine Safety – Reduce Risks > Cage around danger > Control access points > Door Safety Interlocks > Light Curtains
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Functional Safety – Where used
Control System
Functional Safety System
Output (motor / contractor / VFD) Confidential Property of Schneider Electric
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Machine Safety Related Solutions A safety related machine solution would include the following:
Logic
Inputs Guarding & Positioning
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Machine Safety Products
E-Stop
Output
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Safety Inputs at a glance Safety switches for machine gates
XCSPA
XCSA
XCSDM
XY2CH
XY2CE
XCSLE/LF
Safety light curtains
Safety cable pull switches
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Limit Switches
XY2CJ
XUSL 25
Safety Interlock Switches - XCS >
> >
Safety interlock switches send a signal to the safety related control circuit when the gates and guards are closed and it is appropriate to start the machine Safety interlock switches also send a stop signal to the safety related control circuit when the gates or guards are opened so the machine can be stopped Many varieties of safety interlocks are available > > > > > > >
>
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Locking with electromagnet Locking with key release Locking with push button release Rotary shaft Lever type Compact pre-wired Metal or plastic bodies
Most are available with connector options
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Basic Guidelines When designing a door or gate guarding system, these guidelines must be followed: > The actuating key alone must not be used as the sole means to hold the gate or guard closed. A separate locking or latching mechanism must be used to hold the door closed. > The safety interlock switch must not be used as a mechanical stop for the moving guard. A separate mechanical stop must be provided. > The actuating key must not be used as a gate guiding device. Install a guide for the guard to ensure proper alignment. > Actuating keys must be securely attached to gates, guards, and doors only. They should not be attached to cables, cords, or chains.
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The Product Range Type
Non-Contact
Non-Contact
Non-Contact
Non-Contact
Family
XCSDMC
XCSDMP
XCSDMR
XCSDM3/4
Operating Zone
Sao: 0.20 in (5 mm) Sar: 0.59 in (15 mm)
Sao: 0.31 in (8 mm) Sar: 0.79 in (20 mm)
Sao: 0.31 in (8 mm) Sar: 0.79 in (20 mm)
Sao: 0.39 in (10 mm) Sar: 0.79 in (20 mm)
Wiring
Cable or connector
Size
2.01 x 0.63 x 0.28 in
Cable or connector 3.56 x 0.98 x 0.51 in
Cable or connector 30 mm dia. 1.51 in
Cable or connector 3.94 x 1.34 x 1.26 in 28
Non-Contact Safety Interlocks – Why ? >
Food and beverage and pharmaceutical applications do not allow contaminants to be trapped in or around devices
>
Zero operating force is needed – such as lightweight or plexiglass doors where cracking or breakage is prevalent with standard safety interlocks. Non-contact devices have no inherent operating force.
>
Wash down applications where a standard mechanical safety interlock switch would be much more difficult to clean, especially in the actuating key receptacle.
>
Smallest size in the marketplace for Category 4 applications, .63” x 2” x .28”
>
Tolerates gate or guard alignment problems
>
Wider temperature range for a plastic bodied device than any of the competition
>
6 operating directions allows for maximum flexibility of mounting options
>
Suitable for Category 4 safety circuits
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Key Points Primary Selection Factor The primary factor in the selection of safety interlock switches is the access time of personnel vs. the stopping time of the machine, if the: > 
Stopping time of the hazard is less than the access time of personnel to the hazardous area, then the door or guard does not need to locked
> 
Stopping time of the hazard is greater than the access time of personnel to the hazardous area, then the door or guard must be locked until the hazard poses no threat to personnel
This question must be answered first, before any other criteria are considered
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The Product Range Type
Safety Limit Switch
Safety Limit Switch
Safety Limit Switch
Family
XCSM
XCSP
XCSD
Enclosure
Metal
Plastic
Metal
Wiring
Cable
Conduit
Conduit
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Why Safety Limit Switches? >
US and European safety standards require that switches used in safety applications have positive opening contacts.
>
Safety limit switches are many times used in conjunction with safety interlocks for mechanical and electrical redundancy
>
Also used for end of travel and overtravel applications
>
XCS Safety Limit Switches have tamper resistant covers over mounting screws.
>
Red color allows easy visibility and identification of safety related limit switches
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Light Curtains – Type 2 vs Type 4 > Type 2 light curtains > Generally used as a perimeter guard > These devices run a self-check when they are turned on or reset. A component anomaly could cause loss of safety function and won't be detected until the next self-check. > Type 4 Light Curtains > Required in point of operation applications - such as presses where serious injury could result > Point of operation - that point (pinch point) where material is actually positioned and work is being performed during any process such as shearing, punching, forming, or assembling. > These devices continuously check themselves and will detect loss of function immediately.
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Light Curtains – Where used? > Type 2 Light Curtain Applications: > Packaging and assembly plants > Conveyor and mechanical handling systems > Warehousing and storage systems > Waste disposal skips > Robot areas > Type 4 Light Curtain Typical Applications: > Presses (all types), shears and trimmers > Hoisting equipment > Saws (all types) Confidential Property of Schneider Electric
Machine Tools Woodworking machines Assembly machines 34
Different Styles of light curtains > Finger, hand, and body detection Light Curtain Typical Applications: > Protected height 160 – 1810 mm (6” – 72”) > 2 PNP outputs > Operating temperature range: -10 °C +55 °C (14 - +131 F) > Cascadable (master / slave) > Sensing distance from 0 – 20 meters (0 – 65 feet)
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Different Styles of light curtains > IP69K Light Curtains > Protected height 310 – 1060 mm (12” – 42”) > 2 PNP outputs > Operating temperature range: -25 °C +55 °C (-13 - +131 F) > Resistance to acidic and alkaline cleaning agents, and aliphatic hydrocarbons > Sensing distance from 0 – 17 meters (0 – 55 feet)
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XUSL 2/4 Light Curtain > No External > Safety Relay > Required > Lowest installation costs
XUSL2E and XUSL4E compliant with: Type 2, SIL2 – SILCL2 and PLd- Cat.2 Confidential Property of Schneider Electric
Type 4, SIL3, SILCL3 and PLe- Cat.4
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Taut Cable vs. Slack Cable > Taut Cable > Cable is tight (taut) with a specified tension applied to set switch > Device trips if either the cable is pulled or if the cable is loose or cut > The distance the operator has to pull on the cable is constant throughout the cable run > The force the operator has to place on the cable is constant throughout the cable run
> Slack Cable > Cable is slack, and rests on eyelets placed around machine > Device trips only if the cable is pulled > If the cable is loose or cut, the operator can pull on the cable until they reach the end of their rope > The distance the operator has to pull on cable is directly related to the overall cable length, how loose the cable was, and how far the operator was away from the switch. Confidential Property of Schneider Electric
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Requirements for E-Stops (EMO for SEMI) > E-Stop must have absolute priority over all other functions > Must have e-stop capability at each workstation and other locations where e-stop is required > Every machine must have a category 0 or category 1 emergency stop > Must be mushroom push button, cable pull or foot switch (without cover) – Cannot be flat panel types of operators or graphical displays > Must have mechanical latch means (pull to release or rotate) > Shall be initiated by a single human action > Reset of e-stop command shall not restart machinery – only permit restarting > Must (shall) have positive opening contacts > RED actuator with a YELLOW background required > The emergency stop devices must be continuously operable, clearly identifiable, clearly visible and readily accessible Confidential Property of Schneider Electric
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Stop Categories > Three categories of emergency stop function: > Category 0: Immediate removal of power (all machines must have a category 0 or 1 emergency stop) > Category 1: Power to machine actuators to achieve the stop, then the removal of power (all machines must have a Category 0 or 1 emergency stop) > Category 2: Power to machine actuators to achieve the stop; power remains on the circuit
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Key Points > No
teasing
> Red
mushroom actuator
> Positive
opening contact
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Cable Pull Vs. E- Stop Buttons > A machine can be stopped by either an e-stop button or cable pull switch. Which should you use? > An E-Stop button > Designed for an individual’s protection at a single workstation > May be more expensive to use if many operators are in close proximity and each require their own e-stop > Best choice if operators are far apart or if cable pull’s cable would be difficult to run (e.g.: many turns or just physically challenging to mount) > A Cable Pull Switch > Designed for use by several personnel over a longer distance, up to 230feet > One operating cable needs to be run, fewer electrical connections > Can be used in place of many e-stop buttons, reducing installation costs Confidential Property of Schneider Electric
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Safety Interlocks vs. Light Curtains There are a lot of questions on when to use light curtains and when to use guards with safety interlocks Light Curtains can be used where: > Operators need easy physical access to hazardous areas >
Clear visibility of the operation is desired Gates and guards may not be practical
>
They cannot be used where there is potential for flying debris that could harm personnel
>
Safety Interlocks can be used where: ● ● ● ●
Access is not desired or where access needs to be limited Large areas of a machine need to be protected, where there are multiple points of access There may be flying debris, fluids or coolants, or other materials you want to keep away from personnel Lower cost is a primary concern
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Cable Pull Switches XY2CE
XY2CH
Price
XY2CJL/R
XY2CJS
65 feet Confidential Property of Schneider Electric
98 feet
230 feet
Cable length 44
Monitor and processing Type
Safety Relay
Safety Controller
Safety PLC
AS-i
Safety Card
Family
XPS
XPSMC
XPSMF
ASISAFE
Lexium 32
Function
Solution for monitoring one function
Solution for monitoring many functions simultaneously and communication over Safe Ethernet
Solutions using a safety related communications bus
Solutions using a motion controller
Solution for monitoring several functions simultaneously
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Key Points - Logic > Different amount of inputs and different software solutions
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Support resources
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Telemecanique Safety Sensors
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Need for quantification approach Whichever sensors or switches are used, machine builders need to demonstrate and document the functional safety of their machinery in front of regulatory agencies Sistema has become the most popular tool to calculate the safety level of an automation safety chain
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Sistema > Electronic sensors (component/block) > MTTFd, Mission Time, DC > Switches (component) > B10d > Safety related sensors (sub system) > PL, PFHd, category, Mission Time > Available on demand from our specialist sales people, > and directly from www.tesensors.com web site or http:// www.schneider-electric.com/us/en/
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Typical Customer Application Examples
Solutions driven sales will also need: Harmony XB4 - Emergency stop Phaseo ABL8 - Power supply Preventa XUSL - Safety light curtains OsiSense XU Photo-electric when Muting Relay Used Modicon TM3SAFL5R(G) - Safety Module Tesys D - Contactor Harmony XVB - Modular beacon and tower lights Confidential Property of Schneider Electric
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Machine Safety Solutions for Doors, Gates, Panels
• Related Products • Switches, pushbuttons, emergency stop - Harmony XB4 • Switch mode Power supply Phaseo ABL8 • Safety Module - Preventa XPSAC • Safety switches - Preventa XCS • Contactor - TeSys D • Modular beacon and tower light - Harmony XVB
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Machine Safety Solutions for Doors, Gates, Panels
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Key Points > US standards are important to the development of safety related systems here in the US > Many of the requirements are similar to the European (EN) and IEC standards > Many different products and solutions available for cost effective and safety related solutions to meet your requirements
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Š2015 Schneider Electric. All Rights Reserved. All trademarks are owned by Schneider Electric Industries SAS or its affiliated companies or their respective owners.
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Glossary Appendix Functional Safety
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Glossary * >
Safety-Related Parts of Control Systems (SRP/CS)
>
Category
>
Performance Level (PL)
>
Safety Integrity Level (SIL)
>
Mean Time To dangerous Failure (MTTFd)
>
Diagnostic Coverage (DC)
>
Common Cause Failure (CCF)
A part of a control system that responds to input signals and generates safety-related output signals. The classification of safety-related parts of a control, respective their resistance against faults and their behaviour in the fault condition, which is achieved by the structural arrangement of the parts, fault detection and/or by their reliability. The ability of safety-related parts to perform a safety function under foreseeable conditions (which should be taken into account) to fulfil the expected risk reduction. The performance level is indicated in five possible discrete levels from a to e according to Table 1. One of three possible discrete levels for specifying the safety integrity requirements to be allocated to the safety-related electrical control system (SRECS), where the SIL 3 has the highest level of safety integrity for machinery and SIL 1 the lowest. Expectation of the mean time to dangerous failure.
The DC is a measure for the effectivity of diagnostics, may be determined as the ratio between the rate of the detected dangerous failures (λDD) and the rate of total dangerous failures (λD): DC = ΣλDD / ΣλD total The CCF-factor b is a measure for a failure, which is the result of one or more events causing coincident failure of two or more separate channels in a multiple channel (redundant architecture) subsystem, leading to failure of a safety function.
* From EN/ISO 13849-1
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Glossary > > > > >
Risk
Combination of the probability of the occurrence of a harm and severity of that harm.
Risk assessment
Overall process comprising of risk analysis and risk evaluation.
Risk analysis
Combination of the specification of the limits of the machine, hazard identification and risk estimation.
Risk evaluation
Judgment, on the basis of risk analysis, of whether risk reduction objectives have been achieved.
Low Complexity Component
component in which > >
>
failure modes are well-defined, and the behavior under fault conditions can be completely defined
Complex Component
component in which > >
failure modes are not well-defined, or the behavior under fault conditions cannot be completely defined
* From EN/ISO 13849-1
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Appendix 1:Use of suitable materials • correct dimensioning and shaping • proper selection, combination, arrangements, assembly and installation of components/system • correct protective bonding • proper fastening • insulation monitoring • use of de–energisation principle • transient suppression • energy limitation (pressure, speed) • reduction of response time • compatibility • withstanding environmental conditions • secure fixing of input devices • protection against unexpected start–up • protection of the control circuit • sequential switching for circuit of serial contacts of redundant signals • simplification (reduce the number of components in the safety–related system) • separation • proper temperature range • sufficient avoidance of contamination of the fluid • proper range of switching time • limitation of the generation and/or transmission of force and similar parameters • limitation of range of environmental parameters • proper lubrication • proper prevention of the ingress of fluids and dust [Summary of Table A.1, B.1, C.1 and D.1 in [ISO13849-2]
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Appendix 2:Well-tried safety principles • positive mechanically linked contacts • fault avoidance in cables • separation distance • energy limitation • limitation of electrical parameters • no undefined states • failure mode orientation • over–dimensioning • minimise possibility of faults • balance complexity/simplicity • use of carefully selected materials and manufacturing • use of components with oriented failure mode • over–dimensioning/safety factor • safe position • increased OFF force • carefully selection, combination, arrangement, assembly and installation of components/system related to the application • carefully selection of fastening related to the application • positive mechanical action • multiple parts • use of well–tried spring • Proper avoidance of contamination of the fluid • Sufficient positive overlapping in piston valves • Limited hysteresis [Summary of Table A.2, B.2, C.2 and D.2 in [ISO13849-2] 60
Appendix 3: Well-tried component • A “well-tried component” for a safety-related application is a component which has been either a) widely used in the past with successful results in similar applications, or b) made and verified using principles which demonstrate its suitability and reliability for safety-related applications. • switch with positive mode actuation e.g.: push–button, position switch, cam-operated selector switch e.g. for mode of operation • emergency stop device • fuse, circuit breaker, or differential circuit breaker/ RCD (Residual current detection) • switches, disconnectors • main contactor • control and protective switching device or equipment (CPS) • auxiliary contactor (e. g. contactor relay) • relay • transformer • cables • plug and socket • temperature switch • pressure switch • solenoid for valve • Screw • Spring • Cam • Break–pin • [Summary of Table A.3, B.3, C.3 and D.3 in [ISO13849-2]
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Appendix 4:Common Cause Failure (CCF) ●
The common cause failures (CCF) should also be taken into account (see Annex F of EN/ISO 13849-1).
●
In Category B and 1 the common cause failures (CCF) are not relevant.
●
Examples of measures against CCF: ●
prevention of contamination and electromagnetic compatibility (EMC)
●
separation
●
diversity
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Appendix 5 Positive Opening Contacts >
>
>
Traditionally, Positive Opening Contacts have been slow-make slow-break type. There are now snap action type contact units that have positive opening mechanisms which force the NC contacts open to meet EN 60947-5-1. Either type is suitable (and required) for use in safety related applications. The actuator travel for snap acting contact opening is different than the actuator travel to the point of positive opening. If this difference is not designed into the application, the actuator may not be operated far enough to invoke the positive opening function in the event of a contact weld or anomaly. Slow-make slow-break positive opening construction is overwhelmingly PREFEERED in safety related circuits.
Unactuated State Confidential Property of Schneider Electric
Approach Travel
Snap Action Contact Change of State
Positive Opening 63
Appendix 6– Linked Contacts Mechanical link
> Mechanically linked contacts have: > A mechanical link between the contacts. > A minimum distance between the points of an open contact in the event of a closed contact being welded.
Linked contacts
Mechanical guiding (forced guiding) does not allow the closing of the normally closed and normally open contact simultaneously. Contact B
> Linked Contacts are used on > Control Relays > Starters > Contactors/starters > Auxiliary contacts of starters/contactors > Safety Relays Confidential Property of Schneider Electric
Minimum gap
Contact A - welded If an anomaly occurs –i.e.: contact A becomes welded - then contact B stays open 64