YASKAWA F7 Programming Manual page 144

Parameter n3-01 sets the amount of frequency reduction that will be applied in order to create the increase motor slip condition and
lower the DC Bus voltage. Normally this parameter will not need to be adjusted from the factory default. If the OV fault occurs during
HSB increase n3-01 in small increments (~2% per adjustment). n3-01 is set as a percentage of the maximum frequency (E1-04).
n3-02 High-Slip Braking Current Limit
Setting Range: 100 to 200% of Drive rated output current
Factory Default: 150% of Drive rated output current
Parameter n3-02 sets the maximum current to be output during an HSB stop. The higher n3-02 is set the shorter the motor
stopping time will be but the greater the motor winding heating will be. Increasing the setting of n3-02 should only be done in
small increments. Parameter n3-02 is set as a percentage of motor rated current (E2-01).
n3-03 High-Slip Braking Dwell Time at Stop
Setting Range: 0.0 to 10.0 Seconds
Factory Default: 1.0 Seconds
At the end of a HSB action the Drive will hold the frequency reference at the minimum frequency (E1-09) for a period of time
configured by parameter n3-03. If n3-03 is set too short there may be residual motion of the motor shaft after the HSB braking
has completed and the Drive output is shut off. The residual motion can be caused by machine/load inertia.
n3-04 High-Slip Braking Overload Time
Setting Range: 30 to 1200 Seconds
Factory Default: 40 Seconds
The OL7 (HSB Overload) fault will occur if the Drive frequency does not change within the time specified by the n3-04 parameter. The
non-changing frequency can be caused by a load with excessive inertia or a motor that is being overhauled by the load. A good test for the
excessive load inertia is whether the Drive can stop the load normally (w/o a braking resistor but not with HSB) in 180 seconds or less.
Run
Command
HSB
Command
Motor
Motor
Speed
Speed
HSB Current
Output
Current
DC
Voltage
HSB On
N3-02
L2-03
Minimum Baseblock
Fig. 99 High Slip Braking Timing Diagram
Drive will not restart until HSB stop is complete
and run command re-cycled
HSB Off
HSB On
HSB Stop Dwell
Programming 136
N3-03
E1-09
Minimum Frequency
Approx. 90% of
overvoltage trip
t
TIME