5.11.1 Electronic bypass function
The inverter contains complicated sequence circuits for switching between the commercial power supply operation and inverter
operation. Therefore, interlock operation of the magnetic contactor for switching can be easily performed by simply inputting
start, stop, and automatic switching selection signals.
Restart coasting time
Restart cushion time
Start waiting time
Bypass selection at a
frequency from inverter
to bypass operation
frequency range from
bypass to inverter
The coasting time when Pr.57 = "0" is as shown below. (When Pr.162 Automatic restart after instantaneous power failure selection is set to
the initial value.)
FR-F820-00077(1.5K) or lower and FR-F840-00038(1.5K) or lower: 0.5 s
FR-F820-00105(2.2K) to FR-F820-00340(7.5K), FR-F840-00052(2.2K) to FR-F840-00170(7.5K): 1 s
FR-F820-00490(11K) to FR-F820-02330(55K), FR-F840-00250(11K) to FR-F840-01160(55K): 3.0 s
FR-F820-03160(75K) or higher, FR-F840-01800(75K) or higher: 5.0 s
Electronic bypass sequence function
• When operating the motor at 60 Hz (or 50 Hz), the motor can be more efficiently operated with a commercial power supply.
In addition, if the motor cannot be stopped for a long period of time even for an inverter maintenance and inspection, it is
recommended that a commercial power supply circuit be installed.
• When switching between inverter operation and commercial power supply operation, commercial power supply may be
accidentally applied to the output side of the inverter. To avoid such situation, provide an interlock where the magnetic
contactor at the commercial power supply side turns ON at turn OFF of the magnetic contactor at the inverter output side.
The inverter's electronic bypass sequence that outputs timing signals for the magnetic contactors can act as a complicated
interlock between the commercial power supply operation and the inverter operation.
Coasting time differs according to the inverter capacity.
Set the waiting time for the inverter to perform a restart after restoring
0.1 to 30 s
power due to an instantaneous power failure.
0 to 60 s
Set the voltage cushion time for restart.
Without electronic bypass sequence
With electronic bypass sequence
0 to 100 s
Set the operation interlock time for MC2 and MC3.
Set a time period that is a little longer than the time period from the ON
0 to 100 s
signal input to the actual pick-up operation of MC3 (0.3 to 0.5 s).
Inverter output stop (motor coasting) at inverter failure
Automatic switchover to commercial power supply operation at inverter
failure. (Switchover is not possible when an external thermal relay
(E.OHT) or CPU fault (E.CPU) is occurring.)
Set the frequency where the inverter operation is switched to commercial
power supply operation.
0 to 60 Hz
The inverter operation is performed from a start to Pr.139 setting, then it
switches automatically to the commercial power supply operation when
the output frequency is equal to or above Pr.139.
Without automatic switchover
Set the frequency where the commercial power supply operation, which
has been switched from the inverter operation with Pr.139, switches back
to inverter operation.
When the frequency command becomes less than (Pr.139 - Pr.159), the
0 to 10 Hz
motor switches automatically to inverter operation and operates at the
frequency of the frequency command. Turning OFF a inverter start
command (STF/STR) also switches the operation to the inverter
To switch the commercial power supply operation, which has been
switched from the inverter operation with Pr.139, to the inverter operation
again, the inverter start command (STF/STR) is turned OFF. The
operation switches to the inverter operation, and the motor decelerates to
5.11 (A) Application parameters