YOKOGAWA FA-M3V e-RT3 Plus, Hardware Manual

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A3-19
IM 34M06C11-01E
 Immediate Detection Mode
(when F3PU16-0N, F3PU16-0S, F3PU26-0N, F3PU26-0S, F3PU36-0N or F3PU36-0S is used)

Momentary Power Failure Detection
- System operation continues without interruption even if the power fails momentarily
for no longer than 2ms (undetected momentary power failure).
- If a power failure longer than 2ms and less than 10ms occurs, the controller may or
may not recognize a momentary power failure condition because an uncertainty is
involved. When the controller detects a momentary power failure, it holds or resets
its outputs (in accordance with the output set at stop) , it suspends program
execution, and then it turns on the FAIL contact. (Refer to Section A2.3 of this
manual for details on how the FAIL contact works). It also records the date and time
at which the momentary power failure occurred into the error log file in the CPU.
The controller restarts in the reset restart mode after a momentary power failure is
detected.
- The controller always detects any momentary power loss conditions that are longer
than 10ms.

Power Failure Detection
The entire functionality of the controller is disabled when the CPU operating voltage
(+5V) falls below 95% of the rated voltage.

Automatic Recovery
The controller resumes normal operation automatically when the power recovers from a
momentary power failure condition and the CPU operating voltage (+5V) rises above
95% of the rated voltage. The controller restarts in the reset restart mode following the
detection of a power failure condition.

Power on/off sequences
ON
Allowable momentary
power failure time
Momentary power
failure detected
Power failure
detected
Power restored
Power supply
Power Loss
Detected
CPU operating
voltage (+5V)
Reset
Program
FAIL 1 contact
OFF ON OFF ON
Approx. 2 s
Approx. 2 s
OFF
Power
shutdown
Power-on 2 ms or less Longer than 2 ms
Momentary power
failure detected
Power failure detected
Reset restart
Reset restart
Longer than 2 ms
and less than 10 ms
Approx. 3 s
Approx.3 s
FA030308.VSD
Figure A3.16 Detection of Abnormal Supply Voltage Levels in Immediate Detection Mode
(for F3PU16, F3PU26 and F3PU36)