5-128
F codes
E codes
C codes
P codes
H codes
A codes
b codes
r codes
J codes
d codes
U codes
y codes
Ch
ap
. 5
FUNCTION C
O
DES
H69
Automatic Deceleration (Mode selection)
H76 (Torque Limiter, Frequency increment limit for braking)
H69 enables or disables the anti-regenerative control.
In the inverter not equipped with a PWM converter or braking unit, if the regenerative energy returned exceeds the inverter's
braking capability, an overvoltage trip occurs.
To avoid such an overvoltage trip, enable the automatic deceleration (anti-regenerative control) with this function code, and
the inverter controls the output frequency to keep the braking torque around "0" in both the deceleration and constant speed
running phases.
FRENIC-MEGA series of inverters have two braking control modes; torque limit control and DC link bus voltage control.
Understand the feature of each control and select the suitable one.
Control mode
Control process
Operation mode
Features
Torque limit
control
(H69=2 or 4)
Controls the output frequency
to keep the braking torque
around "0."
Enabled during acceleration,
running at the constant
speed, and deceleration.
Quick response.
Causes less overvoltage trip
with heavy impact load.
DC link bus
voltage control
(H69=3 or 5)
Control the output frequency
to lower the DC link bus
voltage if the voltage exceeds
the limiting level.
Enabled during deceleration.
Disabled during running at
the constant speed.
Shorter deceleration time
by making good use of the
inverter's regenerative
capability.
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 forcibly.
Data for H69
Function
Control mode
Force-to-stop with actual deceleration time exceeding
three times the specified one
0 Disable
automatic
deceleration
―
2 Torque
limit
control
Enable
3
DC link bus voltage control
Enable
4 Torque
limit
control
Disable
5
DC link bus voltage control
Disable
Torque Limiter (Frequency increment limit for braking) (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 fre 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.
• Enabling the automatic deceleration (anti-regenerative control) may automatically increase the deceleration time.
• When a braking unit is connected, disable anti-regenerative control. Automatic deceleration control may be
activated at the same time when a braking unit starts operation, which may make the deceleration time fluctuate.
• 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. In such a case, specify a longer deceleration time.
Summary of Contents for FRENIC-MEGA
Page 36: ...2 6 Unit inch mm Refer to Section 2 3 3 9...
Page 356: ...MEMO...
