Interlock
An interlock is a control condition that prevents or changes equipment operation unless defined safety, process, or sequence requirements are satisfied.
What this term means in maintenance
An interlock is a control condition that prevents or changes equipment operation unless defined safety, process, or sequence requirements are satisfied.
Types of interlock
Interlocks may be:
- Safety-related
- Process-related
- Sequence-related
- Mechanical
- Electrical
- Software-based
Practical example
A conveyor cannot start unless the guard switch is closed and the downstream conveyor is running.
Testing
Interlocks should be tested against defined cause-and-effect requirements.
Bypass
Bypassing an interlock requires controlled authorization, risk assessment, visibility, and restoration.
Common mistake
Changing an interlock without management of change can create unexpected process and safety consequences.
How this term differs
Interlock is a condition that prevents or changes equipment operation. It is related to Safety Instrumented System, Safety Integrity Level, and Emergency Shutdown System, but these terms describe different records, measures, roles, strategies, or decisions and should not be used interchangeably.
Related concepts
Related maintenance terms
Keep exploring connected CMMS, reliability, and maintenance planning terms.
Alarm Management
Alarm management is the lifecycle control of industrial alarms so they remain relevant, prioritized, understandable, and actionable.
Bypass Management
Bypass management controls temporary disabling or overriding of alarms, trips, interlocks, protective functions, or equipment safeguards.
Functional Test
A functional test confirms that equipment, a component, or a protective function performs its required operation under defined test conditions.
Interlock FAQs
- What is an interlock?
A condition that prevents or changes equipment operation until defined requirements are satisfied.
- What types exist?
Mechanical, electrical, software, process, sequence, and safety interlocks.
- Can interlocks be bypassed?
Only through controlled authorization, risk assessment, visibility, and restoration.