YASKAWA Varispeed f7, Programming Manual

Page: 130 / 202

Programming 122
Fig. 87 Stall Prevention
If L3-04=2, the intelligent stall prevention function is enabled. The active deceleration time is used as a starting point and the
Drive will attempt to decelerate as quickly as possible without causing the DC Bus voltage to exceed the stall prevention level.
The fastest time possible is 1/10 the active deceleration time.
If L3-04=3, the stall prevention with braking resistor function is enabled. The DC bus voltage level is controlled during fast
deceleration and allows for a faster than normal deceleration time. Use this setting with a braking resistor when overvoltage fault
(OV) sometimes occurs even under settings 1 or 2.
L3-05 Stall Prevention Selection During Running
L3-06 Stall Prevention Level During Running
Setting Range: 30 to 200% of Drive rated output current
Factory Default: 120% of Drive rated output current
The Stall Prevention During Running function will attempt to avoid a Drive OC fault occurrence while the Drive is operating at
a constant speed. If L3-05= “0: Disabled”, the Drive may fault if the load increases sufficiently to cause the output current to
reach the OC fault level (180% of Drive rated output current).
If L3-05= “1: General Purpose”, the Drive is outputting a constant speed, and the Drive’s output current level exceeds the level
set by parameter L3-06 for more than 100 ms the Drive will begin to decelerate at the rate specified by parameter C1-02. The
Drive will continue to decelerate until the output current level drops below the L3-06 level (less a 2% hysteresis). Once the
output current drops below the L3-06 – 2% level the Drive will begin to accelerate at the currently active acceleration rate (either
C1-01 or C1-03).
If L3-05= “2: Decel Time 2”, the Drive will function as described above except C1-04 will be used instead of C1-02 as the
deceleration rate used when the output current exceeds L3-06 for more than 100 ms.
IMPORTANT
In Flux Vector Control Mode (A1-02=3), setting stall prevention with DB resistor (L3-04=3) cannot be done.
Setting Description
0 Disabled
1 Decel Time 1 ( factory default )
2 Decel Time 2
t
a
380/660/760 Vdc
t
Output
Frequency
DC Bus
Voltage
b
a - Set decel time
b - Decel time is extended
Output
Frequency
DC Bus
Voltage
a - Set decel time
b - Decel time is extended
t
380/660/760Vdc
t
a
b