Panasonic FPS Series, User Manual

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Installation and Wiring
FP Σ User's Manual
76
6.2 Safety Instructions for Wiring
In certain applications, malfunction may occur for the following reasons:
•
Power ON timing differences between the PLC system and input/output or motorized
devices
• A response time lag when a momentary power drop occurs
•
Abnormality in the PLC, external power supply circuit, or other devices
In order to prevent a malfunction that results in a system shutdown, choose the adequate
safety measures listed below:
Interlock circuit
When a motor's clockwise/counter-clockwise operation is controlled, provide an interlock
circuit that prevents clockwise and counter-clockwise signals from being input into the motor
at the same time.
Emergency stop circuit
Provide an emergency stop circuit externally to turn off the power supply of controlled devices
in order to prevent a system shutdown or an irreparable accident if a malfunction occurs.
Start-up sequence
The PLC should be operated only after all of the field devices are energized. To ensure this
sequence, the following measures are recommended:
•
Turn ON the PLC with the operation mode selector set to PROG mode, and then
switch to RUN mode
•
Program the PLC so as to disregard the inputs and outputs until the field devices are
energized
NOTE
When stopping the operation of the PLC, also have the input/output devices
turned off after the PLC has stopped operating.
Grounding
When installing the PLC next to devices that generate high voltages from switching, such as
inverters, do not ground them together. Use an exclusive ground for each device.
Momentary power failures
The FP Σ continues to operate normally for a certain period of time in case of a momentary
power failure. We call this the momentary power off time. However, if the power failure
exceeds this period of time, operation depends on the combination of units, the power supply
voltage, etc. In some cases, operation mirrors a power supply reset.
For the momentary power off time values, see "General Specifications" on page 274.