Mitsubishi Electric FR-F800 Series Instruction Manual page 482

 Undervoltage avoidance function (Pr.261 = "11 or 12", Pr.294)
• When "11 or 12" is set to Pr.261, the deceleration time is adjusted (shortened) to prevent an undervoltage from occurring
during deceleration at occurrence of power failure.
• Adjust the downward frequency slope and the response level using Pr.294 UV avoidance voltage gain. Setting a large
value improves the response to the bus voltage.
 Automatic adjustment of deceleration time (Pr.261 = "21 or 22", Pr.294,
Pr.668)
• When "21 or 22" is set to Pr.261, the deceleration time is automatically adjusted to keep (DC bus) voltage constant in the
converter when the motor decelerates to a stop at a power failure. Setting of Pr.262 to Pr.266 is not required.
• If a phenomenon such as motor vibration occurs during operation of the deceleration time automatic adjustment function,
adjust the response level by setting the Pr.668 Power failure stop frequency gain. Increasing the setting improves the
response to change in the bus voltage. However, the output frequency may become unstable.
• If setting Pr.294 UV avoidance voltage gain lower also does not suppress the vibration, set Pr.668 lower.
Pr.261 = 21
Power
supply
Output
frequency
STF
Y46
 Deceleration stop by the Power failure stop external (X48) signal
• By turning OFF X48 signal, the power failure time deceleration-to-stop function is activated. This function is used, for
example, when an external power failure detection circuit is installed.
• To use the power failure time deceleration-to-stop function for the separated converter type, use X48 signal. Connect the
terminal to which the PWF signal of the converter unit is assigned and the terminal to which the X48 signal of the inverter
is assigned.
• In the initial setting, the X48 signal is used with the normally closed (NC contact) input specification. Use Pr.606 Power
failure stop external signal input selection to change the specification to the normally open (NO contact) input.
• To use the X48 signal, set "48" in any parameter from Pr.178 to Pr.189 (Input terminal function selection) to assign the
function to an input terminal.
 During deceleration at occurrence of power failure (Y46) signal
• After deceleration by a power failure, the inverter is not restarted even though the start command is input. Check the During
deceleration at occurrence of power failure (Y46) signal at a power failure. (For example, when input phase loss protection
(E.ILF) occurs.)
• The Y46 signal is turned ON during deceleration at occurrence of power failure and in a stop status after deceleration at
occurrence of power failure.
• For the Y46 signal, set "46 (positive logic)" or "146 (negative logic)" in any parameter from Pr.190 to Pr.196 (Output
terminal function selection) to assign the function.
 Power failed (Y67) signal
• Y67 signal turns ON when the output is shut off due to detection of power failure (power supply fault) or undervoltage, or
the power failure time deceleration-to-stop function is activated.
• To use the Y67 signal, assign the function by setting "67 (positive logic)" or "167 (negative logic)" in any parameter from
Pr.190 to Pr.196 (output terminal function selection).
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During deceleration at
occurrence of power failure
Deceleration time : Automatic adjustment
During stop at occurrence
of power failure
Turn OFF STF once to make acceleration again
search engine
Time
5. PARAMETERS
5.11 (A) Application parameters
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