Fuji Electric FRENIC-HVAC User Manual page 475

In addition, during deceleration triggered by turning the run command OFF, 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 anti-regenerative control to apply when three times the specified deceleration
time is elapsed, thus decelerating the motor forcibly.
Data for H69
0
2
3
4
5
 Torque Limiter for braking (Frequency increment limit) (H76)
- Data setting range: 0.0 to 500.0 (Hz)
Since increasing the output frequency too much in the torque limit control mode 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 an
overvoltage trip in some cases. Increasing the H76 data improves the anti-regenerative
control capability.
 Automatic deceleration (Operation level) (H114)
- Data setting range: Auto, 0.0 to 50.0 (%)
H114 specifies the anti-regenerative control operation level under torque limit control. The
inverter controls the output frequency to keep the braking torque at the value specified with
H114. When H114 = Auto (factory default), the anti-regenerative control starts with the
inverter internal fixed value (approx. 2% to 5%). Do not change the factor default except
when necessary.
• Enabling
automatically increase the deceleration time.
• If the set deceleration time is too short, the DC link bus voltage of the inverter
rises quickly, and consequently, the automatic deceleration may not follow the
voltage rise. If this is the case, set longer deceleration time.
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
OH1 or OLV, 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
Inherit
0.01 to 100.0
OFF
Control mode
Disable automatic deceleration
Torque limit control
DC link bus voltage control
Torque limit control
DC link bus voltage control
the automatic deceleration
Decelerate the motor with the preset deceleration time
Decelerate the motor by deceleration rate from 0.01 to 100.0 (Hz/s)
Cancel overload prevention control
6-165
6.3 Details of Function Codes
Function
Force-to-stop with actual
deceleration time exceeding three
times the specified one
―
Enable
Enable
Disable
Disable
(anti-regenerative
Function
control) may