Hitachi WJ Series

Chapter 9 Inverter Functions
9-7-2
9.7.2 Starting with DC Braking
 How to start operation after stopping the rotating fan?
 How to start operation after stopping the motor rotation?
 By performing "External DC braking [DB](07)" before outputting a frequency to the motor, you
can start operation after stopping the motor rotation.
 The following settings are required for DC braking at start.
- Set "DC braking selection [A051]" to "Enable (01)".
- Set the required braking force for "DC braking force at start [A057]".
- Set a value other than 0.0 for "DC braking active time at start [A058]".
 DC braking at start is performed for the time set in "DC braking active time at start [A058]" after
the RUN command is applied.
 Set and operate the DC braking force at start and DC braking active time at start, paying
attention to motor heating.
 When "Enable (Output frequency < [A052]) (02)" is set for "DC braking selection [A051]",
regardless of whether the product is starting or stopping, DC braking starts when both the
frequency command and output frequency are at or below the "DC braking frequency [A052]".
In such a case, "DC braking force [A054]" is enabled, regardless of whether the product is
starting or stopping, and both "DC braking force at start [A057]" and "DC braking active time at
start [A058]" will be disabled. For details, refer to "9.7.8 Stopping with DC Braking".
 If "Carrier Frequency [b083]" is 2 kHz or greater, the DC braking force is limited. For details, refer
to "9.7.8 Stopping with DC Braking".
Code
Item
Description
Data
[A051]
DC braking
selection
Internal DC braking: Enable
01
Internal DC braking: Enable (Output frequency < [A052])
02
[A052]
DC braking
frequency
Sets the level of frequency at which DC braking is
performed when "Enable (Output frequency < [A052]) (02)"
is selected for [A051].
0.00 to 60.00 (Hz)
[A054]
DC braking
force
Sets the braking force for when DC braking is performed
when "Enable (Output frequency < [A052]) (02)" is selected
for [A051].
0 to 100 (%)
(ND mode)
0 to 70 (%)
(LD mode)
[A057]
DC braking
force at start
Adjusts the DC braking force at start when "Enable (01)" is
selected for [A051]. When this is set to 100%, the maximum
braking force is applied.
0 % (Weak: zero current)  100 % (Strong: rated current)
0 to 100 (%)
(ND mode)
0 to 70 (%)
(LD mode)
[A058]
DC braking
time at start
Sets the DC braking time at start when "Enable (01)" is
selected for [A051].
0.0 to 60.0 (s)
◼ Operation of DC braking at start
([A051] = 01)
◼ Operation of frequency command DC braking
([A051] = 02)
* If a frequency command higher than [A052] is set
before operation, as shown in the figure on the right
(Example 1), DC braking at start is not performed.
(Example 1)
(Example 2)
* As shown in the figure on the right (Example 2), if the RUN
command is turned ON while the frequency command and
output frequency are at or less than [A052] at start due to
an analog frequency command or the like, then the DC
braking will start. When the frequency command reaches
[A052] + 2 Hz or more, the DC braking is released and
normal operation begins.
RUN
command
Output
frequency
ON
Frequency
command
[A052] Set frequency
ON
DC
braking
[A058]
DC
braking
RUN
command
Output
frequency
ON
A
!
Q