Second Acceleration And Deceleration Functions - Hitachi SJ300 Series Instruction Manual

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"A" Group: Standard Functions
Second
Acceleration and
Deceleration
Functions
frequency
2CH
input
Optimal Accel/Decel Operation, continued...
The acceleration time is controlled to maintain output current below the level set by the
Overload Restriction Function if enabled (Parameters B021/B024, B022/B025, and B023/
B026). If Overload Restriction is not enabled, then the current limit used is 150% of the
inverter's rated output current.
The deceleration time is controlled so that the output current is maintained below 150% of the
inverter's rated current, and the DC bus voltage is maintained below the OV Trip level (358V or
770V).
NOTE: DO NOT use Optimal Accel/Decel (A085 = 02) when an application...
• has a requirement for constant acceleration or deceleration
• has a load inertia more than (approx.) 20 times the motor inertia
• uses internal or external regenerative braking
• uses any of the vector control modes (A044 = 03, 04, or 05). This function is ONLY
compatible with V/F control.
NOTE: If the load exceeds the rating of the inverter, the acceleration time may be increased.
NOTE: If using a motor with a capacity that is one size smaller than the inverter rating, enable
the Overload Restriction function (B021/B024) and set the Overload Restriction Level (B022/
B025) to 1.5 times the motor nameplate current.
NOTE: Be aware that the acceleration and deceleration times will vary, depending on the
actual load conditions during each individual operation of the inverter.
The SJ300 inverter features two-stage acceleration and deceleration ramps. This gives flexibil-
ity in the profile shape. You can specify the frequency transition point, the point at which the
standard acceleration (F002) or deceleration (F003) changes to the second acceleration (A092)
or deceleration (A093). These profile options are also available for the second motor settings
and third motor settings. All acceleration and deceleration times are time to ramp from zero
speed to full speed or full speed to zero speed. Select a transition method via A094 as depicted
below. Be careful not to confuse the second acceleration/deceleration settings with settings for
the second motor!
A094=00
Accel 2
Accel 1
1
0
frequency
A094=01
Accel 2
t A095
Accel 1
0
Frequency
transition point
t