SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.

Chapter 4 Explanation of Functions
(4) Internal DC braking (triggered only when the output frequency reaches a set frequency) (A051: 02)
You can also operate the internal DC braking function so that DC braking is applied to the motor when the
inverter output frequency falls to the DC braking frequency setting (A052) or below.
When the internal DC braking function is used in this mode, the external DC braking described in Item (2)
and the internal DC braking described in Item (3) cannot be used.
In this mode, DC braking operates only when the operation command signal is on (i.e., the start command
is input).
The inverter starts DC braking when both the frequency set by the frequency command and the current
output frequency fall to the DC braking frequency setting (A052) or below. (See example 7-a.)
When the frequency set by the frequency command increases to the "setting of 'A052' + 2 Hz" or more, the
inverter stops DC braking and restores its normal output. (See example 7-a.)
If the frequency set by the frequency command is 0 Hz when the start command is input via an analog
input terminal, the inverter will start operation with DC braking because both the frequency set by the
frequency command and current output frequency are 0 Hz. (See example 7-b.)
If the operation command signal (start command) is turned on when the frequency command specifies a
frequency larger than the DC braking frequency (A052), the inverter will start operation with the normal
output.
(Example 7-a)
(Example 7-b)
Operation
command
ON
Operation
command
ON
A052
Frequency
command
A052
Frequency
command
Output
frequency
Output
frequency
How the inverter returns to the normal output varies depending on the setting of the DC braking/edge or
level detection for [DB] input (A054).
(a) Edge mode
(b) Level mode
Operation
command
ON
Operation
command
ON
A052
Frequency
command
A052
Frequency
command
Output
frequency
Output
frequency
A053
4 - 23