Hitachi Sj7002 Owners Manual

“A” Group: Standard Functions
Configuring Drive Parameters
3–18
DC Braking 
SettingsThe DC braking feature can provide additional  stopping torque when compared to a normal 
deceleration to a stop. It  can also ensure the motor and load  are stopped before acceleration.
When decelerating  – DC braking is 
particularly useful at low speeds when 
normal deceleration torque is minimal. 
During deceleration,  the inverter injects 
a DC voltage into the motor windings 
during decelerati on below a frequency...

SJ7002 Inverter
Configuring Drive Parameters
3–19
You can configure DC braking to initiate in one of two ways:
1. Internal DC braking  – Set A051=01 to enable internal  braking. The inverter automatically 
applies DC braking as configured  (during stopping, starting, or both).
2. External DC braking  – Configure an input terminal  with option code 7 [DB] (see “
Exter-
nal Signal for DC Injection Braking” on page 4–19 for more details). Leave A051=00, 
although this setting is ignored when a [DB] input is...

“A” Group: Standard Functions
Configuring Drive Parameters
3–20
Derating of DC Braking  – The inverter uses an internal carrier frequency (set by A059) to 
generate a DC braking voltage (do not confuse wi th main inverter output carrier frequency set 
by B083). The maximum DC braking force available  to the inverter is more limited with higher 
DC braking carrier frequency settings fo r A059 according to the graphs below.
Frequency-
related FunctionsFrequency Limits – Upper and lower 
limits can be...

SJ7002 Inverter
Configuring Drive Parameters
3–21
Jump Frequencies –  Some motors or machines exhibit  resonances at particular speed(s), 
which can be destructive for prolonged running at  those speeds. The inverter has up to three 
jump frequencies  as shown in the graph. The hysteresis around the jump frequencies causes the 
inverter output to skip around the sensitive frequency values.   
Acceleration 
Pause FunctionThe acceleration pause function can be 
used to minimize the occurrence of...

“A” Group: Standard Functions
Configuring Drive Parameters
3–22
PID ControlWhen enabled, the built-in PID loop calculates  an ideal inverter output value to cause a loop 
feedback process variable (PV) to move closer  in value to the setpoint (SP). The current 
frequency command serves as the SP. The PID loop  algorithm will read the analog input for the 
process variable (you specify either current or voltage input) and calculate the output.
 A scale factor in A075 lets you multiply the  PV by a factor,...

SJ7002 Inverter
Configuring Drive Parameters
3–23
Automatic 
Vo l t a g e
Regulation (AVR) 
FunctionThe Automatic Voltage Regulation (AVR) feature keeps the inverter output voltage at a 
relatively constant ampl itude during power input fluctuations. Th is can be useful if the installa-
tion is subject to input volta ge disturbances. However, the  inverter cannot boost its motor 
output to a voltage higher than the power input  voltage. If you enable this feature, be sure to 
select the proper voltage...

“A” Group: Standard Functions
Configuring Drive Parameters
3–24
NOTE: DO NOT use Optimal Accel/Decel (A 085 = 02) when an application...
  acceleration or deceleration


 044 = 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...

SJ7002 Inverter
Configuring Drive Parameters
3–25
NOTE:  For A095 and A096 (and for 2nd motor settings), if you set a very rapid Acc1 or Dec1 
time (less than 1.0 second), the in verter may not be able to change rates to Acc2 or Dec2 before 
reaching the target frequency. In that case, the in verter decreases the rate of Acc1 or Dec1 in 
order to achieve the second ramp to the target frequency.
A093 Deceleration (2) time setting — — 0.01 to 99.99, 100.0 to 999.9, 
1000. to 3600. (seconds)15.0 15.0 15.0 ✔...

“A” Group: Standard Functions
Configuring Drive Parameters
3–26
Accel/Decel 
CharacteristicsStandard (default) acceleration and deceleration is linear with time. The inverter CPU can also 
calculate other curves shown in the graphs belo w. The sigmoid, U-shape, and reverse U-shape 
curves are useful for favoring the load characteri stics in particular applications. Curve settings 
for acceleration and deceleration  are independently selected via parameters A097 and A098, 
respectively. You can use the...

SJ7002 Inverter
Configuring Drive Parameters
3–27
The acceleration and dece leration curves can deviate from a st raight line to a varying degree. 
Parameters A131 and A132 contro l the amount of deviation for the acceleration and decelera-
tion curves respectively. The following graphs show intermediate output frequency points as a 
percentage of the target frequency, for 25%,  50%, and 75% acceleration time intervals.   
Additional 
Analog Input 
SettingsThe parameters in the following table adjust the...