Mitsubishi Electric FR-A700 Technical Manual page 119

1.5.9 Input/output phase loss protection selection
(1) Input phase loss protection (E.ILF)
When [Pr. 872 = 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 input phase is lost when [Pr. 872 = 1] (with input
phase loss protection)
(instantaneous power failure stop function is enabled)
are set in
A700 F700
(E.ILF) is not provided but power-failure deceleration is
made. For
E700
protection (E.ILF) is activated.
*1 As phase loss is detected according to the bus
voltage change in
be detected if the load is light. As phase loss is
detected according to the bus voltage change, it
can not be detected if the load is light. Large
unbalanced phase-to-phase voltage of the three-
phase power supply may also cause input phase
loss protection (E.ILF).
*2 When an input phase loss occurs in the R/L1 and
S/L2 phases of
protection is not provided but the inverter output is
shut off.
*3 If an input phase loss continues for a long time, the
converter section and capacitor lives of the inverter
will be shorter.
Initial
[Pr. ] Name
Value
A700
Input phase
F700
loss
872
protection D700
selection
E700
(2) Output phase loss protection (LF)
The output current unbalance due to the phase loss
is checked by the output phase loss detection. When
the current value between the lost phase and other
two phases differs, it is regarded as output phase
loss and the inverter will come to a fault.
When [Pr. 251 = 0], output phase loss protection
(E.LF) becomes invalid.
Initial
[Pr. ] Name
Value
Output phase
failure
251
protection
selection
1) When the output phase loss protection
activates properly
The output phase loss protection (E.LF) activates
when
a) The average output current of the phase where
lowest current flows is 5% or less than the
rated inverter current
and
common
*1
and [Pr. 261
, input phase failure protection
, input phase
D700
, phase loss cannot
E700 D700
, input phase loss
A700 F700
Setting
Description
Range
Without input
0 phase loss
0
protection
With input phase
1
loss protection
1
common
Setting
Description
Range
Without output
0 phase loss
protection
1
With output phase
1
loss protection
(common)
b) The difference between the average output
Output current
0]
5% of the
rating
failure
2) When the output phase loss protection
malfunctions
When the motor capacity is smaller than the
inverter capacity, the output current value is small
as compared to the rated inverter current. At this
time, if any of the phases enters the dead zone
(assumed as 0A if within 5% of the rated inverter
current value) due to noises, etc. when the output
current flows more than 5% on average, the
output
malfunction. To prevent this, set 0 in [Pr. 251
Output phase loss protection selection] and make
output phase loss protection invalid.
Output current
The average current exceeds 5%
5% of the
rating
112
SPECIFICATIONS
common
current of other two phases and rated inverter
current is 5% or more
b)
a)
Time
phase loss protection
The current enters the dead zone
The period of time where the current
of one phase is instantly less than 5%
Time
U phase current
V phase current
W phase current
(E.LF) may
U phase current
V phase current
W phase current