Input/Output Phase Failure Protection Selection (Pr. 251, Pr. 872); Overspeed Detection (Pr. 374); Encoder Signal Loss Detection (Pr. 376) - Mitsubishi Electric FR-B-750 to 75K Instruction Manual

Operation setting at alarm occurrence

4.14.3 Input/output phase failure protection selection (Pr. 251, Pr. 872)

You can disable the output phase failure protection function that stops the inverter output if one of the inverter
output side (load side) three phases (U, V, W) opens.
The input phase failure protection function of the inverter input side (R/L1, S/L2, T/L3) can be made valid.
Parameter
Number
Output phase failure protection
251
selection
Input phase failure protection
872
selection
(1) Output phase failure protection selection (Pr. 251)
⋅ When Pr. 251 is set to "0", output phase failure protection (E.LF) becomes invalid.
(2) Input phase failure protection selection (Pr. 872)
⋅ When Pr. 872 is set to "1", input phase failure protection (E.ILF) is provided if a phase failure of one phase among
the three phases is detected for 1s continuously.
REMARKS
If an input phase failure has occurred when Pr. 872 = "1" (input phase failure protected) and a value other than "0" (power failure
stop function valid) is set in Pr. 261, input phase failure protection (E.ILF) is not provided but power-failure deceleration is made.
CAUTION
⋅ When an input phase failure occurs in the R/L1 and S/L2 phases, input phase failure protection is not provided but the
inverter output is shut off.
⋅ If an input phase failure 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

4.14.4 Overspeed detection (Pr. 374)

Parameter
Number
374 Overspeed detection level
Motor speed
Pr. 374
ALM

4.14.5 Encoder signal loss detection (Pr. 376)

When the encoder signal is lost during encoder feedback control, orientation control, signal loss detection
(E.ECT) is activated to stop the inverter output.
Parameter
Number
Encoder signal loss
376 detection enable/disable
selection
* Setting can be made only when the FR-A7AP is mounted.
158
Name Initial Value
Refer to page 152
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
Setting Range
0
0
1
Description
Without output phase failure protection
With output phase failure protection
Without input phase failure protection
With input phase failure 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 stops the inverter output.
Description
Signal loss detection is invalid
Signal loss detection is valid