YASKAWA T1000A Technical Manual page 254

5.11 S: Functions for Textile Applications
3. When the supply power is restored during Power KEB and the drive is set to reaccelerate to the frequency reference in effect before
KEB, a small step in the output frequency might occur at the end of KEB deceleration and before the S4-12 time starts.
Figure 5.93
Main Power Supply
0 V
DC Bus Voltage
0 V
Output Frequency
0 Hz
Synchronous Accel/Decel (KEB 2)
Synchronous KEB can be used when multiple drives have to be decelerated during power loss while keeping the speed
ratio between the drives constant.
KEB 2 begins when one of the conditions that triggers the KEB function becomes true. To have multiple drives remain in
sync with one another while accelerating and decelerating during KEB 2, Yaskawa recommends setting a multi-function
input to "KEB" (H1-
KEB 2 decelerates the drive using the deceleration time set in S5-01 and S5-02. This deceleration time is referred as the
time needed to decelerate from the active frequency reference to stop.
When the power returns the drive accelerates back to the frequency reference using the time set in S5-05. This
acceleration time is referred as the time needed to accelerate from the current output frequency to the frequency
reference.
254
Power Loss
S4-03 (KEB Start Voltage)
S4-04 (KEB Start dv/dt Level)
S4-10 (KEB 1Phase Loss
Detection Time)
S5-07 (Frequency Gain at KEB Start during Constant Speed)
S5-08 (Frequency Gain at KEB Start during Acceleration)
S5-09 (Frequency Gain at KEB Start during Deceleration)
Deceleration using
S5-01 and S5-02 or Power KEB
Figure 5.93 KEB Function when S4-01 = 1 or 3
= 65 or 66) to activate the synchronous accel/decel provided by KEB 2.
Power Restored
S4-06 (KEB End Voltage)
S4-11 (KEB Target Voltage)
S4-12 (KEB
Hold Time)
S4-07 (KEB End
Detection Time)
YASKAWA ELECTRIC SIEP C710616 30B YASKAWA AC Drive T1000A Technical Manual
S5-05 (KEB Synchronous
Acceleration Time) or
C1-01, C1-03, C1-05, C1-07
(Acceleration Time 1, 2, 3, 4)