Emergency Stop Circuit And Interlock Circuit - Fuji Electric MICREX-SX series SPF User Manual

Section 4 Installation and Wiring

(3) Emergency stop circuit and interlock circuit

• To improve operational safety, it is necessary to include an emergency stop circuit which can stop the system operation in an
emergency or at fault occurrence.
The emergency stop circuit should be implemented in a PLC external circuit.
a) Emergency stop circuit
• Configure it in an external circuit.
A normal emergency stop circuit is built into an interlock circuit that detaches an I/O control power at failure.
b) Interlock circuit
• An interlock relay (MC) opens to interrupt the power supply in an emergency or at fault occurrence.
For the interlock circuit, contacts of a relay which works only during normal operation of PLC are inserted into a maintained
circuit.
It is necessary to create PLC application software to turn the contacts of the relay off when a fault is detected.
An emergency stop circuit varies depending on the configuration of the PLC used or controlled object. The example circuit is
shown below.
Transformer
Prepare to
MC
operate
AUX
Emergency
stop
MC
4-15
MC
Use output
unit
PLC
AUX