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Operation setting at fault occurrence
4.18.3 Input/output phase loss protection selection (Pr. 251, Pr. 872)
You can disable the output phase loss protection function that trips the inverter if one phase of the inverter output
side (load side) three phases (U, V, W) is lost.
The input phase loss protection function of the inverter input side (R/L1, S/L2, T/L3) can be valid.
Parameter
Number
Output phase loss protection
251
selection
Input phase loss protection
872
selection
(1) Output phase loss protection selection (Pr. 251)
When Pr. 251 is set to "0", output phase loss protection (E.LF) becomes invalid.
(2) 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.
REMARKS
If an input phase loss has occurred when Pr. 872 = "1" (input phase loss protected) and a value other than "0" (power failure stop
function valid) is set in Pr. 261, input phase loss protection (E.ILF) is not provided but power-failure deceleration is made.
CAUTION
When an input phase loss occurs in the R/L1 and S/L2 phases, input phase loss protection is not provided but the inverter
output is shut off.
If an input phase loss continues for a long time, the converter section and capacitor lives of the inverter will be shorter.
Parameters referred to
Pr. 261 Power failure stop selection
4.18.4 Overspeed detection (Pr. 374)
Parameter
Number
374
Overspeed detection level
Motor speed *
Pr. 374
ALM
4.18.5 Encoder signal loss detection (Pr. 376)
When the encoder signal is lost during encoder feedback control, orientation control, or vector control, signal loss
detection (E.ECT) is activated to trip the inverter.
Parameter
Number
Encoder signal loss
376
detection enable/disable
selection
* Setting can be made only when the FR-A7AP/FR-A7AL (option) is mounted.
280
Name
Initial Value
Refer to page 274
Name
Initial Value
140Hz
Coast to stop
Time
ON
E.OS
Name
Initial Value
Setting Range
0
1
1
0
0
1
Setting Range
0 to 400Hz
* The output frequency and Pr. 374 are compared during
Real sensorless vector control.
V/F
V/F
V/F
Setting Range
0
0
1
Description
Without output phase loss protection
With output phase loss protection
Without input phase loss protection
With input phase loss protection
Description
When the motor speed reaches or exceeds
the speed set in Pr. 374 during encoder
feedback control, Real sensorless vector
control, or vector control, over speed (E.OS)
occurs and the inverter trips.
Magnetic flux
Magnetic flux
Magnetic flux
Vector
Vector
Vector
Description
Signal loss detection is invalid
Signal loss detection is valid
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