Hitachi WJ Series User Manual page 222

Chapter 9
DC braking by frequency command ([A051] = "Enable (Output frequency < [A052]) (02)")
A
 To perform DC braking by frequency command, set the "DC braking selection [A051]" to "Enable
(Output frequency < [A052]) (02)", and then set the "DC braking frequency [A052]".
 When DC braking by frequency command is enabled, the external DC braking using the [DB]
terminal and DC braking when stopping described above do not function.
 DC braking is applied once both the frequency command and the output frequency fall below
[A052] during operation.
 When the frequency command reaches [A052] + 2 Hz or more during operation, the DC braking
is released and normal operation begins.
 DC braking does not trigger if a frequency command of [A052] + 2 Hz or higher is preset, and
then the RUN command is turned on. (Example 6)
 If the frequency command is preset to "0 Hz" by analog input, etc. and the RUN command is
turned on, DC braking is applied at startup because both the command frequency and output
frequency are below the [A052] setting. (Example 7)
 DC braking operation varies depending on the edge operation/level operation settings in the
"DC braking operation method selection [A056]". Configure edge operation or level operation
settings to match the system in use, referring to the operation examples provided in the figure
below. When edge operation is selected, set the "DC braking active time at stop [A055]".
◼
(Example 6) Set a frequency command equal to or higher than [A052] before operation.
If the frequency command is less than/greater than [A052] during operation.
(Example 6-a) [A056] = "Edge operation (00)"
RUN
command
Frequency
command
DC braking
frequency [A052]
Output
frequency
DC braking
* DC braking is applied if the frequency command is less than [A052] when the RUN command is on.
In the case of edge operation, DC braking is applied for the duration of the [A055] setting when the frequency command and output
frequency falls below [A052].
In the case of level operation, DC braking is applied until the RUN command turns on when the frequency command and output
frequency falls below [A052].
◼ (Example 7) Set a frequency command equal to or less than [A052] before operation due to the use of
analog frequency commands. If the frequency command is less than/greater than [A052]
after operation.
(Example 7-a) [A056] = "Edge operation (00)"
RUN
command
DC braking
frequency [A052]
Frequency
command
Output
frequency
DC braking
* DC braking is applied if the frequency command is less than [A052] when the RUN command is on.
In the case of edge operation, DC braking is applied for the duration of the [A055] setting when the frequency command and output
frequency falls below [A052].
In the case of level operation, DC braking is applied until the RUN command turns on when the frequency command and output
frequency falls below [A052].
ON
[A055]
ON
[A055] [A055]
(Example 6-b) [A056] = "Level operation (01)"
RUN
command
Frequency
command
DC braking
frequency [A052]
Output
frequency
DC braking
(Example 7-b) [A056] = "Level operation (01)"
RUN
command
DC braking
frequency [A052]
Frequency
command
Output
frequency
DC braking
9-7-14
Inverter Functions
ON
ON