YASKAWA SGM7J-A5A, Technical Supplement

Page: 601 / 622

Appendices
Capacity Selection for Regenerative Resistors
583
Appendices
Selecting External Regenerative Resistor
Use Yaskawa’s SigmaJu, an AC servo drive capacity selection program, to determine if you
need an External Regenerative Resistor.
You can use one of the following two methods to manually calculate whether an External Regenerative
Resistor is required. Refer to the following information if you do not use the SigmaJu.
Simple Calculation (page 583)
Calculating the Regenerative Energy (page 588)
Simple Calculation
When driving a Servo Motor with a horizontal shaft, check if an External Regenerative Resistor is required
using the following calculation method. The calculation method depends on the model of the SERVOPACK.
 SERVOPACK Models SGD7S-R70A, -R90A, -1R6A, and -2R8A
Regenerative resistors are not built into the above SERVOPACKs. The total amount of energy that can
be charged in the capacitors is given in the following table.
If the rotational energy (E
S
) of the Servo Motor and load exceeds the processable regenerative energy,
then connect an External Regenerative Resistor.
Calculate the rotational energy (E
S
) of the servo system with the following equation:
E
S
= J

(n
M
) 2 /182 (Joules)
•
J = J
M
+ J
L
• J
M
: Servo Motor moment of inertia (kg

m
2
)
• J
L
: Load moment of inertia at motor shaft kg

m 2 )
• n
M
: Servo Motor operating motor speed (min
-1
)
Applicable SERVOPACK
Processable Regenerative Energy
(Joules)
Remarks
SGD7S-
R70A, R90A, 1R6A 24.2
Value when main circuit input voltage
is 200 VAC
2R8A 31.7