interlock is a device used to help prevent a machine from harming its operator or damaging itself by stopping the machine when tripped.
Trapped key interlocking is a method of ensuring safety in industrial environments by forcing the operator through a predetermined sequence using a defined selection of keys, locks and switches.
It is called “Trapped Key” as it works by releasing and trapping keys in a predetermined sequence. After the control or power has been isolated, a key is released that can be used to grant access to individual or multiple doors
1. A mechanical device that prevents a component from functioning when another component is functioning or situated in a particular way.
2. A stretchy fabric knitted with interlocking stitches by alternating sets of needles on a circular knitting machine.
A safety interlock is a normally open valve that closes in the event of a process upset. Usually it is attached to electronics that perform logic operations on process conditions, and only trips (closes) in the event that exceeding those conditions will cause harm to equipment or personnel.
Process Interlock : Something that prevents incorrect operation or possible damage to the process or equipment.
Safety Interlock : Something that prevents possible damage or death to people operating that process or equipment.
DCS and many PLC systems are not considered reliable enough for you to risk your life on. Hence safety PLC systems require a greater level of reliability. In addition there are usually legal considerations involved.
Safety interlocks are implemented in your ESD system which can be relay logic, PLC or safety PLC.
Process interlocks are implemented in your DCS.