Safety Measures; Safety Instructions - Panasonic fp2/fp2sh User Manual

Installation and Wiring
4.6

Safety Measures

4.6 Safety Measures
4.6.1

Safety Instructions

Precautions Regarding System Design
In certain applications, malfunction may occur for the following reasons:
Power on timing differences between the PLC system and I/O or motorized devices
An operation time lag when a momentary power failure occurs
Abnormality in the PLC, external power supply, or other devices
In order to prevent a malfunction resulting in system shutdown choose the adequates
safety measures listed in the following:
Interlock circuit
When a motor clockwise/counter-clockwise operation is controlled, provide an interlock
circuit that prevents clockwise and counter-clockwise signals from inputting into the mo-
tor at the same time.
Emergency stop circuit
Add an emergency stop circuit to controlled devices in order to prevent a system shut-
down or an irreparable accident when malfunction occurs.
Start up sequence
The PLC should be operated after all of the outside devices are energized. To keep this
sequence, the following measures are recommended:
Turn on the PLC with the mode selector set to the PROG. mode, and then switch to the
RUN mode.
Program the PLC so as to disregard the inputs and outputs until the outside devices are
energized.
Note
When stopping the operation of PLC also, have the I/O devices
turned off after the PLC has stopped operating.
Alarm function
When an alarm occurs, the PLC turns off the output and stops operation. Even while
in this condition, take the appropriate safety precautions outside of the PLC to ensure
no malfunction or damage is transmitted to anywhere else in the system.
Grounding
When installing the PLC next to devices that generate high voltages from switching,
such as inverters, do not ground them together.
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FP2/FP2SH