5.4 Details of Function Codes
5-199
Chapter 5 Function Code
Details of
Function Codes
F codes
E codes
C codes
P codes
H63 to H70
A codes
b codes
r codes
J codes
d codes
U codes
y codes
The 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.
Table 5.4-133
Control Method Control process Operation mode Features
Torque limit
control
(H69 = 2 or 4)
Controls the output
frequency to keep
the braking torque at
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.
Torque Limiter (braking) (increasing frequency limiter) (H76)
- Data setting range: 0.0 to 500.0 (Hz)
In the torque limit method, the output frequency is increased, and the torque is limited. The increasing
frequency limiter (H76) is provided because the output frequency, which is too high, is dangerous. Due to
this limiter, the output frequency does not increase to "set frequency + H76" or higher. Note that the torque
limiter activated restrains anti-regenerative control, resulting in an overvoltage trip in some cases. Increasing
the H76 data improves the anti-regenerative control capability.
In addition, when the operation command is turned off, the frequency increases due to anti-regenerative
control and may not stop according to the load status. For safety measure, 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. Selection of valid/invalid of the function is possible by the H69 setting.
- Due to anti-regenerative control, there are cases that the deceleration time automatically
become long.
- 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.
H70
Overload Prevention Control
H70 sets the decelerating rate of the output frequency in overload prevention control. 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.
Table 5.4-134
Data for H70 Function
0.00
Follow the deceleration time set in F08 or E11.
0.01 to 100.0
Decelerate by deceleration rate from 0.01 to 100.0 (Hz/s)
999
Disable overload prevention control
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