How to Select Safety Relays             Image credit:  Automationdirect | Banner Engineering Corp. | Schmersal Inc.   Safety relays are electromechanical switching devices designed to prevent failure in critical switching operations.   Understanding Safety Relays Relays are designed to isolate circuits or control a high powered circuit using a low power signal. Simple relays contain a magnetic core wrapped in a wire coil,...
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Q & A on Safety Relays

We asked our users for their input on Safety Relays. Here are the results of 84 users familiar with Safety Relays.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice |

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing safety relay design?
12 answers
Answers:
Microprocessor based technologies are providing flexible functionality, reducing space requirements, improving diagnostics, and generally reducing the T.C.O.
~Ken M, Technical manager, Laverton Nth., Australia
Safety relays now can be cascaded to perform simple logic behavior.
~Craig I, Engineer, Melbourne, Australia
ABS (automatic brake system); efficiency of power/energy consumption.
~Subur Subur, Engineer, Batam, Indonesia
OSHA safety specifications, company standards and z136.1.
~Jeff T, Marketing/Sales, Commerce twsp, MI
Programmable relay permits the optimal use.
~Technical Support, Alger, Algeria
Programmable safety relay
~Goran Poznic, Sales engineer, Stara Pazova, Serbia
Modular build, fiber optic
~Marek Kozlowski, Engineer, Clinton, CT
Anti defeatable systems
~Engineering, Design, Nottinghamshire, Great Britain
Electronic interlocking
~Maurice Headland, Marketing/Sales, Johannesburg, South Africa
Remote controlled.
~Syed D, Engineer, Riyadh, Saudi arabia
SMD technology
~Marketing/Sales, Belgium
I/O platforms
~Engineering, Design, Columbus, OH

Q:
From your perspective, which companies are creating the most innovative safety relays?
14 answers
Answers:
Leuze electronic (Asi based technologies), Pilz, Sick, Rockwell
~Ken M, Technical manager, Laverton Nth., Australia
Trying to determine, as selection seems limited.
~Jeff T, Marketing/Sales, Commerce twsp, MI
Pilz and Schmersal...also Rockwell is coming.
~Marketing/Sales, Belgium
We only have PILZ and try to standardize.
~Maintenance/Facilities Management, Leeton, Australia
ASO Safety, Sick, Banner, Omron/STI
~Marketing/Sales, Rockaway, NJ
Banner (fiber optic), Pilz
~Marek Kozlowski, Engineer, Clinton, CT
Nais, Coto, Pickering
~Subur Subur, Engineer, Batam, Indonesia
Pilz Allen Bradley
~Engineering, Design, Nottinghamshire, Great Britain
Mors-Smitt, Holland
~Maurice Headland, Marketing/Sales, Johannesburg, South Africa
Siemens, Crouzet.
~Syed D, Engineer, Riyadh, Saudi arabia
Pilz, Sick
~Goran Poznic, Sales engineer, Stara Pazova, Serbia
Rockwell
~Craig I, Engineer, Melbourne, Australia
SIK, A-B
~Engineering, Design, Columbus, OH
Omron
~Technical Support, Alger, Algeria

Applications and UseTop

Q:
What are some of the applications you have used safety relays for?
22 answers
Answers:
Two out of three trip loops, four out of six loops, and two out of five loops on a Honeywell ESD system as well as other loops, which although they do not contain voter logic from the inputs, are critical to the process as far as safety is concerned.
~Technical Support/Services, Secunda, South Africa
As components, part of safety control system hardware. As modules, used to monitor Safety devices (emergency stops, interlocks, AOPD's, etc) and interface to Isolating devices (Contactors, safety valves etc.), in automation equipment.
~Ken M, Technical manager, Laverton Nth., Australia
In all safety applications from cat.3 or PLd. So for surveillance of E-stops,door switches,light curtains, 2-hand control devices, safety mats etc...
~Marketing/Sales, Belgium
Machine safety, light curtains, emergency stop, captive key and two hand controls, all kinds of machines in the automotive industry.
~Engineering, Consulting, Hartlepool, United Kingdom
Monitoring safety light curtains and emergency stop circuits on automatic palletizers.
~Other, Alfreton, United Kingdom
Safety control circuits for motor-driven equipment, light curtains and safety gates.
~Engineering, Design, Columbus, OH
Emergency stop circuits, contactor anti-weld in circuits, run permissive circuits
~Engineering, Design, Nottinghamshire, Great Britain
In a safety circuit of the running machinery; E-stop, guards, jog button.
~Marek Kozlowski, Engineer, Clinton, CT
Used to safe and simulation on test functional of automotive relay board.
~Subur Subur, Engineer, Batam, Indonesia
Safety Mats, Safety Edges, Safety bumovers for machine tool industry
~Marketing/Sales, Rockaway, NJ
Protection of systems balanced and starting engines in few steps.
~Technical Support, Alger, Algeria
E-stop control of multiple motors, guard interlocking
~JEFF K, SENIOR CONTROLS DESIGNER, MARION, NY
Safety curtain, safety laser scanner, area protection
~Goran Poznic, Sales engineer, Stara Pazova, Serbia
Safety doors/ covers on paper converting mc-s.
~Technical Support/Services, Budapest, Hungary
Guarding safety circuits on packing machines.
~Maintenance/Facilities Management, Leeton, Australia
Safety gate protection for the machines.
~Syed D, Engineer, Riyadh, Saudi arabia
General machine guarding applications
~Craig I, Engineer, Melbourne, Australia
Railway signalling system
~Maurice Headland, Marketing/Sales, Johannesburg, South Africa
As per international law.
~Architect/Builder/Contractor, AL AIN, United Arab Emirates
Class 1 laser safety
~Jeff T, Marketing/Sales, Commerce twsp, MI
Robot cell guarding
~Engineering, Design, Cudahy, WI
Machine guarding
~General Corporate Mgmt, Smithfield, RI

Q:
Please share with us any “non-standard” applications that safety relays have been used for.
3 answers
Answers:
Used to provide remote device (Safety valves) cross monitored back checking.
~Ken M, Technical manager, Laverton Nth., Australia
Hazardous location
~Marek Kozlowski, Engineer, Clinton, CT
Unspecified
~Technical Support, Alger, Algeria

Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of safety relays?
5 answers
Answers:
I know of several accidents, which resulted in fatality, which were attributed to incorrect application, installation or operation of safety relays. In one case the selection of the appropriate device was also questioned as the requirements were not properly understood and documented. This resulted in the wrong device being used.
~Ken M, Technical manager, Laverton Nth., Australia
For example, using an automatic reset wiring on the safety relay which is controlling a light curtain in a robot cell.
~Marketing/Sales, Belgium
Yes, because people don't understand safety standard.
~Goran Poznic, Sales engineer, Stara Pazova, Serbia
Non activation of ABS on automotive application.
~Subur Subur, Engineer, Batam, Indonesia
Non malheuresement.
~Technical Support, Alger, Algeria

FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
9 answers
Answers:
Simple modular input expansion (allow low cost multiple input expansion for high risk applications where maximum diagnostics and redundancy is required).
~Ken M, Technical manager, Laverton Nth., Australia
Multifunction between protection and allowed to perform operations remotely programmable operating.
~Technical Support, Alger, Algeria
Dual input, ability to connect to multiple safety devices and cascading ability.
~Craig I, Engineer, Melbourne, Australia
Heavy current with DC or AC operating coils. Also latching safety relays.
~Maurice Headland, Marketing/Sales, Johannesburg, South Africa
For many simple applications, define with rotary switch function.
~Goran Poznic, Sales engineer, Stara Pazova, Serbia
Dual channel, tamper evident, smaller the better, fail safe
~Jeff T, Marketing/Sales, Commerce twsp, MI
Better wiring information (examples) and simpler wring.
~JEFF K, SENIOR CONTROLS DESIGNER, MARION, NY
Create the safety relay with SMD package.
~Subur Subur, Engineer, Batam, Indonesia
More inputs
~Marketing/Sales, Rockaway, NJ

Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using safety relays?
12 answers
Answers:
Sometimes limiting yourself to one supplier, means you do not get the best solution for a given application. Choose a supplier who knows their weaknesses and will help you find the right alternative when you need it. Talk to several suppliers on a regular basis, technology and standards can change and more sources of information will help you keep up to date and find the right solution/partner/supplier.
~Ken M, Technical manager, Laverton Nth., Australia
Study specifications of relays offered before purchasing and whether they comply to international standards.
~Maurice Headland, Marketing/Sales, Johannesburg, South Africa
Make sure you cam trust the supplier of the product,; you should look for third party certification.
~Craig I, Engineer, Melbourne, Australia
A-B modular system. Avoid a module MSR338DP. It can stick and you have to cycle power to reset it.
~Marek Kozlowski, Engineer, Clinton, CT
Make sure they are certified to proper safety standard...not just 'design to meet'.
~Marketing/Sales, Rockaway, NJ
Highly recommended for security protection of industrial installations.
~Technical Support, Alger, Algeria
Make sure it's not going to be obsolete the day after you buy it.
~Engineering, Design, Columbus, OH
Check the spec to get the good live time of used.
~Subur Subur, Engineer, Batam, Indonesia
Understand your safety categories and needs.
~JEFF K, SENIOR CONTROLS DESIGNER, MARION, NY
Use a quality brand.
~Marketing/Sales, Belgium
Sale and using
~Goran Poznic, Sales engineer, Stara Pazova, Serbia
Research
~Jeff T, Marketing/Sales, Commerce twsp, MI

Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of safety relays?
7 answers
Answers:
Research, Research, Research. Do not take suppliers word as gospel, make sure you understand what your application needs and check it yourself, with the supplier's assistance.
~Ken M, Technical manager, Laverton Nth., Australia
I think we need to ensure maximum security of networks for parallel and also a better selectivity that allows the appropriate response.
~Technical Support, Alger, Algeria
Do not over design or get too complicated. Break down your systems into smaller groups if possible.
~JEFF K, SENIOR CONTROLS DESIGNER, MARION, NY
Understand the correct operation of the relays before attempting to fault find.
~Maintenance/Facilities Management, Leeton, Australia
Please use the relay with protect diode to avoid damage of relay.
~Subur Subur, Engineer, Batam, Indonesia
Watch out to do correct wiring according to the standards!!
~Marketing/Sales, Belgium
Good training
~Goran Poznic, Sales engineer, Stara Pazova, Serbia


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