Fuji Electric Frenic-Mini - Page 302

9-100
H69
Automatic Deceleration (Anti-regenerative control) (Mode selection)
H76 (Torque Limiter, Frequency increment limit for braking)
H69 specifies anti-regenerative control.
In inverters not equipped with a PWM converter or braking resistor, if regenerative energy
returned exceeds the inverter's braking capability, an overvoltage trip occurs.
When H69 = 1: The anti-regenerative control is functionally equivalent to that of the original
FRENIC-Mini series (FRNC1-). That is, when the DC link bus voltage exceeds
the preset voltage limiting level, the inverter lengthens the deceleration time to three times the
specified time to decrease the deceleration torque to 1/3. In this way, the inverter reduces the
regenerative energy tentatively. This control applies only in deceleration. When the load on
the motor results in a braking effect, the control does not have any effect.
When H69 = 2 or 4: The inverter controls the output frequency to keep the braking torque at
around 0 N·m in both acceleration/deceleration and constant speed running phases in order to
avoid an overvoltage trip.
Since increasing the output frequency too much under anti-regenerative control is dangerous,
the inverter has a torque limiter (Frequency increment limit for braking) that can be specified
by H76. The torque limiter limits the inverter's output frequency to less than "Reference
frequency + H76 setting."
Note that the torque limiter activated restrains the anti-regenerative control, resulting in a trip
with an overvoltage alarm in some cases. Increasing the H76 data (0.0 to 400.0 Hz) makes the
anti-regenerative control capability high.
In addition, during deceleration triggered by turning the run command OFF, the
anti-regenerative control increases the output frequency so that the inverter may not stop the
load depending on the load state (huge moment of inertia, for example). To avoid that, H69
provides a choice of cancellation of the anti-regenerative control to apply when three times
the specified deceleration time is elapsed, thus decelerating the motor.
Data for H69 Function
0 Disable
1 Enable (Lengthen the deceleration time to three times the specified time
under voltage limiting control) (Compatible with the original FRENIC-Mini
series (FRNC1-)
2 Enable (Torque limit control: Cancel the anti-regenerative control if the
actual deceleration time exceeds three times the specified one.)
4 Enable (Torque limit control: Disable force-to-stop processing.)
Enabling the anti-regenerative control may automatically increase the deceleration
time.
When a brake resistor is connected, disable the anti-regenerative control.
H70 Overload Prevention Control
H70 specifies the decelerating rate of the output frequency to prevent a trip from occurring
due to an overload. This control decreases the output frequency of the inverter before the
inverter trips due to a heat sink overheat or inverter overload (with an alarm indication of
0h1 or 0lu , respectively). It is useful for equipment such as pumps where a decrease in the
output frequency leads to a decrease in the load and it is necessary to keep the motor running
even when the output frequency drops.
Data for H70 Function
0.00 Decelerate the motor by deceleration time 1 (F08) or 2 (E11)
0.01 to 100.00 Decelerate the motor by deceleration rate from 0.01 to 100.00 (Hz/s)
999 Disable overload prevention control
In equipment where a decrease in the output frequency does not lead to a decrease in
the load, the overload prevention control is of no use and should not be enabled.