Operation setting at fault occurrence
4.14.2 Input/output phase loss protection selection (Pr. 251, Pr. 872)
You can choose whether to make Input/output phase loss protection valid or invalid.
Output phase loss protection is a function to stop the inverter output if one of the three phases (U, V, W) on the
inverter's output side is lost.
Input phase loss protection is a function to stop the inverter output if one of the three phases (R/L1, S/L2, T/L3) on the
inverter's input side is lost.
Output phase loss
Input phase loss protection
The above parameters can be set when Pr. 160 Extended function display selection = "0". (Refer to page 197)
Output phase loss protection selection (Pr. 251)
If phase loss occurs during inverter operation (except for during DC brake operation, or output frequency is 1Hz or less),
output phase loss protection (E.LF) activates, and inverter trips.
When Pr. 251 is set to "0", output phase loss protection (E.LF) becomes invalid.
Input phase loss protection selection (Pr. 872)
When Pr. 872 is set to "1", input phase loss protection (E.ILF) is provided if a phase loss of one phase among the three
phases is detected for 1s continuously.
If an input phase loss continues for a long time, the converter section and capacitor lives of the inverter will be
If the load is light or during a stop, lost phase cannot be detected because detection is performed based on the
fluctuation of bus voltage. Large unbalanced phase-to-phase voltage of the three-phase power supply may also
cause input phase loss protection (E.ILF).
Phase loss can not be detected during regeneration load operation.
4.14.3 Earth (ground) fault detection at start (Pr. 249)
You can choose whether to make earth (ground) fault detection at start valid or invalid. Earth (Ground) fault detection is
executed only right after the start signal is input to the inverter.
Protective function will not activate if an earth (ground) fault occurs during operation.
Earth (ground) fault
detection at start
The above parameter can be set when Pr. 160 Extended function display selection = "0". (Refer to page 197)
As detection is executed at start, output is delayed for approx. 20ms every start.
If an earth (ground) fault is detected with "1" set in Pr. 249, output side earth (ground) fault overcurrent (E.GF) is detected and
the inverter trips. (Refer to page 305)
If the motor capacity is smaller than the inverter capacity when using the 5.5K or higher, earth (ground) fault detection may not
Without output phase loss protection
With output phase loss protection
Without input phase loss protection
With input phase loss protection
Without earth (ground) fault detection
With earth (ground) fault detection