Machine Safety
Machine Safety for Industrial Automation and Control Systems
Automated machinery needs to operate productively while protecting the people who operate, maintain and work around it. Machine safety therefore needs to be considered as an integral part of the control system rather than an addition made after the machine has been designed.
Safety functions may involve emergency stops, guarding, interlocks, safety relays, safety PLCs, drives and other control equipment working together to place machinery into an appropriate safe state when required.
Stratos provides machine safety engineering as part of industrial automation projects, helping businesses develop, upgrade and maintain safety-related control systems around their machinery, processes and operational requirements.
What Is Machine Safety?
Machine safety encompasses the measures used to reduce risks associated with operating, accessing and maintaining industrial machinery.
Within an automated control system, this can involve:
Emergency stop systems.
Safety interlocks.
Machine guarding interfaces.
Safety switches.
Light curtains.
Safety relays.
Safety PLCs.
Safe drive functions.
Access monitoring.
Safety-related control circuits.
The appropriate solution depends on the machine, its hazards, how people interact with it and the required safety functions.
Machine Risk Assessment and Safety Requirements
Effective machine safety begins by understanding the hazards associated with the equipment and how people may be exposed to them.
A machine risk assessment helps identify hazards and determine the measures required to reduce risk.
Considerations may include:
Moving machinery.
Crushing and trapping points.
Rotating equipment.
Unexpected machine movement.
Access during operation.
Maintenance activities.
Stored energy.
Operator interaction.
Start-up and restart conditions.
Existing safeguards.
The findings provide the foundation for defining appropriate safety functions and control measures.
Safety PLC Systems
Emergency stop systems provide a means of initiating a safe response when an immediate hazardous condition occurs.
An emergency stop circuit needs to consider more than simply removing power.
Depending on the machinery, the required response may involve:
Stopping hazardous movement.
Removing drive commands.
Activating appropriate safe functions.
Maintaining necessary control functions.
Preventing unexpected restart.
Providing clear reset procedures.
Emergency stop functionality should be developed around the behaviour of the machine and the risks created by stopping different equipment.
Machine Guarding and Safety Interlocks
Physical guarding helps prevent access to hazardous machinery, while safety interlocks monitor whether protected areas have been opened or accessed.
Safety devices may include:
Guard switches.
Interlocked doors.
Safety gates.
Light curtains.
Safety scanners.
Trapped-key systems.
Access switches.
Position monitoring.
The automation system needs to respond correctly when a safety device changes state and prevent hazardous operation where the required safety conditions are not satisfied.
Safety Relays and Safety Circuits
Not every application requires a safety PLC.
Safety relays can provide an effective solution for defined safety functions such as emergency stops, guard monitoring and other relatively straightforward applications.
Safety circuit design may consider:
Required safety function.
Number of devices.
Reset behaviour.
Feedback monitoring.
Fault detection.
Equipment stopping.
Machine restart.
Control architecture.
The appropriate technology should be selected according to the requirements of the machinery rather than complexity for its own sake.
Drives and Safe Motion Functions
Modern drive systems can provide safety-related functions that help control hazardous machine movement.
Depending on the equipment and application, this may include functions associated with safely removing torque or controlling movement during particular operating conditions.
Drive safety may be relevant to:
Conveyors.
Rotating machinery.
Motors.
Automated production equipment.
Material handling systems.
Machine access requirements.
The required functionality should be considered alongside the wider machine safety architecture and control philosophy.
Machine Safety and Control Panel Design
Safety-related components need to be correctly incorporated into the electrical control system.
As a control panel manufacturer, Stratos can consider machine safety requirements alongside PLC hardware, drives, motor controls, power distribution and the wider automation architecture.
Control panel considerations may include:
Safety PLCs.
Safety relays.
Protective devices.
Emergency stop circuits.
Drive safety connections.
Safety I/O.
Circuit segregation.
Device identification.
Electrical documentation.
Integrating safety requirements during control panel design helps create a more coordinated system than adding safety equipment after the panel has already been developed.
Machine Safety Upgrades and Modernisation
Older machinery may contain safety systems developed around equipment and practices that have since become outdated.
Changes to machinery, production requirements or access arrangements can also mean that existing safeguards no longer reflect how equipment is currently being used.
Machine safety upgrades may include:
Replacing obsolete safety relays.
Introducing safety PLCs.
Improving guard monitoring.
Updating emergency stops.
Adding safety devices.
Updating control panels.
Improving diagnostics.
Updating documentation.
Integrating modern drive safety functions.
Where appropriate, improvements can be incorporated into wider PLC, control panel or machine modernisation projects.
Machine Safety Validation and Testing
Safety-related control functions need to be tested to confirm that the installed system responds as intended.
Testing may include:
Emergency stop operation.
Guard interlocks.
Safety switches.
Light curtains.
Safety PLC inputs and outputs.
Reset functions.
Fault detection.
Drive safety functions.
Prevention of unexpected restart.
Functional safety behaviour.
Results should be documented appropriately so there is a clear record of the functions tested and the condition of the system at handover.
Maintaining Machine Safety Systems
Machine safety needs to remain effective throughout the operational life of the equipment.
Machinery changes, replacement components, control system modifications and production alterations can all affect the original safety arrangement.
Ongoing reviews may consider:
Safety device condition.
Emergency stop functionality.
Guard interlocks.
Safety PLC diagnostics.
Control panel condition.
System modifications.
Documentation.
Obsolete safety components.
Previous faults.
Where ongoing automation support is required, maintenance and service contracts can incorporate appropriate control system and machine safety checks alongside wider PLC, control panel and automation maintenance.
Why Choose Stratos for Machine Safety?
Machine safety is closely connected to the wider automation system. Safety devices, PLC logic, drives, control panels and machinery need to operate together correctly for safety functions to perform as intended.
Stratos combines control panel engineering, PLC programming and industrial automation expertise, allowing machine safety requirements to be considered within the context of the complete control system.
Whether you're developing new machinery, modifying an existing production system or modernising ageing safety equipment, our engineers can help integrate the required safety functionality into a practical and maintainable automation solution.
Integrate Safety into Your Automation System
Machine safety should work as part of the control system, not around it. Stratos develops and upgrades safety-related automation incorporating control panels, PLCs, drives, interlocks and machine safety devices to create practical solutions around industrial machinery and production requirements.
Speak to our engineers about machine safety for a new automation project, machinery modification or existing control system upgrade.
Frequently Asked Questions
What is an industrial machine safety system?
A machine safety system uses measures such as guarding, emergency stops, interlocks, safety relays, safety PLCs and drive safety functions to help reduce risks associated with industrial machinery.
What is a safety PLC?
A safety PLC is a controller designed for safety-related applications. It can monitor multiple safety devices and execute defined safety functions within machinery and automated production systems.
Does every machine need a safety PLC?
No. The appropriate safety architecture depends on the machine and required safety functions. Some applications may be suitably implemented using safety relays, while more complex systems may benefit from a safety PLC.
Can older machine safety systems be upgraded?
Yes. Existing machinery can be assessed and safety-related control systems can potentially be modernised through updated safety devices, relays, safety PLCs, drives, control panels and associated automation equipment.
Should machine safety systems be tested regularly?
Safety-related functions should remain effective throughout the machine's operating life. Appropriate inspection and testing requirements depend on the machinery, risk assessment, safety functions, manufacturer requirements and applicable standards.