YASKAWA A1000 Series Technical Manual page 270

5.8 L: Protection Functions
Setting 4: Operation with reduced speed
If an overheat alarm occurs, the operation is continued but the speed is reduced to the level set in parameter L8-19. If
after 10 s the oH alarm is still present, the speed is reduced once more. The amount of reduction depends on how often
the alarm repeats. If the oH alarm disappears while the drive is operating at a reduced speed, then the drive will switch
back to the previous speed it was reduced to before.
oH alarm. A digital output programmed for 4D is switched when the oH alarm is still active after ten reduction cycles.
Figure 5.104
Output frequency
f
ref
f × (L8-19)
ref
f × (L8-19) 2
ref
f × (L8-19) 3
ref
4
f × (L8-19)
ref
oH alarm number
Digital ouput (4D)
L8-19: Frequency Reduction Rate during Overheat Pre-Alarm
■
Specifies how much the output frequency is reduced when L8-03 is set to 4 and an oH alarm is present. Set as a factor of
the maximum output frequency.
No.
L8-19
L8-05: Input Phase Loss Protection Selection
■
Enables or disables the input phase loss detection.
No.
L8-05
Setting 0: Disabled
Setting 1: Enabled
Enables input phase loss detection. As detection is performed by measuring the DC bus ripple, a phase loss fault (PF) can
also be triggered by a power supply voltage imbalance or main circuit capacitor deterioration. Detection is disabled if:
• The drive is decelerating.
• No Run command is active.
• Output current is less than or equal to 30% of the drive rated current.
■ L8-07: Output Phase Loss Protection Selection
Enables or disables the output phase loss detection, which is triggered when the output current falls below 5% of the
drive rated current.
Note: 1. Output phase loss detection can mistakenly be triggered if the motor rated current is very small compared to the drive rating. Disable
this parameter in such cases.
2. Output phase loss detection is not possible when the drive is running a PM motor with light load.
270
10 s 10 s
10 s
oH
Alarm
oH
Alarm
oH
Alarm
Figure 5.104 Output Frequency Reduction During Overheat Alarm
Name
Frequency Reduction Rate During Overheat Pre-Alarm
Name
Input Phase Loss Protection Selection
Figure 5.104 explains the operation with reduced speed during an
10 s 10 s 10 s
Reset oH
Alarm Reset oH
Alarm
YASKAWA ELECTRIC SIEP C710616 27C YASKAWA AC Drive A1000 Technical Manual
common_TMonly
10 s
oH
etc.
Alarm
time
Setting Range
0.1 to 0.9
Setting Range
0 or 1
Default
0.8
Default
1