Operation selection at power failure
and instantaneous power failure
(4) Restart coasting time (Pr. 57)
⋅ Coasting time is the time from when the motor speed is detected until automatic restart control is started.
⋅ Set Pr. 57 to "0" to perform automatic restart operation. The coasting time is automatically set to the value below.
Generally this setting will pose no problems.
⋅ Operation may not be performed well depending on the magnitude of the moment (J) of inertia of the load or
running frequency. Adjust the coasting time between 0.1s and 5s according to the load specifications.
(5) Restart cushion time (Pr. 58)
⋅ Cushion time is the length of time taken to raise the voltage appropriate to the detected motor speed (output
frequency prior to instantaneous power failure when Pr. 162 = "1" or "11").
⋅ Normally the initial value need not be changed for operation, but adjust it according to the magnitude of the
moment (J) of inertia of the load or torque.
⋅ Pr. 58 is invalid during encoder feedback control (Pr. 162 = "2, 12"), real sensorless vector control or vector control.
Changing the terminal assignment using Pr. 178 to Pr. 189 (input terminal function selection) may affect the other functions. Please
make setting after confirming the function of each terminal.
When automatic restart operation is selected, undervotage protection (E.UVT) and instantaneous power failure protection
(E.IPF) among the alarm output signals will not be provided at occurrence of an instantaneous power failure.
The SU and FU signals are not output during a restart. They are output after the restart cushion time has elapsed.
Automatic restart operation will also be performed after a reset made by an inverter reset is canceled or when a retry is made
by the retry function.
Automatic restart after instantaneous power failure function is invalid when load torque high speed frequency control (Pr. 270 =
"2, 3") is set.
Provide mechanical interlocks for MC1 and MC2. The inverter will be damaged if the power supply is input to the
inverter output section.
When automatic restart after instantaneous power failure has been selected, the motor and machine will start
suddenly (after the reset time has elapsed) after occurrence of an instantaneous power failure. Stay away from
the motor and machine. When you have selected automatic restart after instantaneous power failure function,
apply in easily visible places the CAUTION stickers supplied to the installation guideline.
♦ Parameters referred to ♦
Pr. 7 Acceleration time, Pr. 21 Acceleration/deceleration time increments
Pr. 13 Starting frequency
Refer to page 175
Pr. 65, Pr. 67 to Pr. 69 Retry function
Pr. 78 Reverse rotation prevention selection
Pr. 178 to Pr. 189 (input terminal function selection)
00080 or less
00040 or less
(6) Automatic restart operation adjustment (Pr. 163 to
Refer to page 268
Refer to page 306
Refer to page 228
00110 to 00330
00460 to 02150
00060 to 00170
00230 to 01100
Pr. 165, Pr. 611)
⋅ Using Pr. 163 and Pr. 164, you can adjust the voltage rise time at a
restart as shown on the left.
⋅ Using Pr. 165, you can set the stall prevention operation level at a
⋅ Using Pr. 611, you can set the acceleration time until the set
frequency is reached after automatic restart operation is performed
besides the normal acceleration time.
⋅ If the setting of Pr. 21 Acceleration/deceleration time increments is
changed, the setting increments of Pr. 611 does not change.
Refer to page 173
02880 or more
01440 or more