Mitsubishi Electric MELSEC iQ-R Series Safety Manual page 112

Guard interlock circuit
■Safety application overview
This application prevents the guard from being opened until a robot is de-energized with the spring-lock safety switch on the
guard of a safety barrier.
The safety switch is usually interlocked with spring. By applying a voltage to a solenoid, the interlock is released and the
guard can be opened. The robot cannot be started while the interlock is released or the guard is open.
This section shows an example where the interlock of the safety switch is released by pressing the stop switch and the safety
switch is re-interlocked by pressing the reset switch.
This controls the start and stop of a robot by turning on or off the main contact of the contractor which opens and closes the
power source of a robot.
Connect the safety switch and electromagnetic contactors to a safety programmable controller.
The Safety CPU controls on or off of the electromagnetic contactors with program.
When the safety programmable controller detects an error with the self-diagnostics, outputs to the electromagnetic contactors
turn off independent of the program.
In this case, regardless of the program, the outputs remain off until the Safety CPU or safety remote I/O module is reset.
Configure the program so that the following functions can be achieved.
1.
Check that safety is ensured (the safety switch is on state) and the worker presses the reset switch first. Pressing the
start switch turns on the electromagnetic contactors.
2.
When a safety electromagnetic contactor is welded, input the safety electromagnetic contactor (normally closed contact)
to the safety programmable controller to prevent starting, and check for welding.
3.
To avoid undesired operation of the reset switch and start switch at welding or short-circuit, set the reset switch and start
switch so that they are activated only when turned on and off.
4.
Pressing the stop switch turns off the electromagnetic contactor output. After that, release the interlock to the safety
switch (the guard can be opened after the interlock is released).
5.
Pressing the reset switch re-interlocks the safety switch.
6.
When an error is detected in the safety remote I/O module after operation starts, outputs to the electromagnetic
contactors turn off.
(Partially quoted from "Safety Guide Book - the safety measures of machinery in the workplace": Nippon Electric Control
Equipment Industries Association)
5 SAFETY APPLICATION CONFIGURATION EXAMPLES
110
5.1 System Configured by a Safety CPU