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User Constant Settings and Functions
5.6.2 Calculating the Required Capacity of Regenerative Resistors
5 -86
D
n = J
L
/J
M
D
J
M
:
Servomotor rotary inertia (kg·m
2
) (oz·in·s
2
)
D
J
L
:
Motor axis conversion load inertia (kg·m
2
) (oz·in·s
2
)
Servopacks with Capacities of 6.0 kW or More
Servopacks with capacities of 6.0 kW or more do not have built-in regenerative resistors. The
following table shows the allowable frequencies in regeneration mode when the Servopack is
combined with the JUSP-RA04 or JUSP-RA05 Regenerative Resistor Unit.
The equation used to calculate the allowable frequency from the Servomotor drive conditions
andloadinertia arethe sameastheone giveabove forServopack withcapacitiesof0.5 to5.0 kW.
Voltage
Series
Allowable Frequencies in Regeneration Mode (r/min)
Voltage
Capacity
Symbol
55
75
1A
1E
200 V
SGMGH-
j
A
j
A
26
36
36
32
SGMGH-
j
A
j
B
44
--
--
--
400 V
SGMGH-
j
D
26
18
36
32
J
J
By Calculating the Regenerative Energy
This section shows the procedure for calculating the regenerative resistor capacity when accel-
eration and deceleration operation is as shown in the following diagram.
Rotation speed
Motor torque
T
L
: Load torque
t
D
0
0
Regenerative
torque
N
M
: Motor rotation speed
T
Calculation Procedure
The procedure for calculating the capacity is as follows:
Step
Item
Symbol
Equation
1
Find the rotational energy of the servo system.
E
S
E
S
= JN
M2
/182
2
Find the energy consumed by load system loss
during the deceleration period.
E
L
E
L
= (
p
/60) N
M
T
L
t
D
3
Calculate the energy lost from Servomotor
winding resistance.
E
M
(Value calculated from “Servo-
motor Winding Resistance Loss”
diagrams)
¢
t
D
4
Calculate the servoamp energy that can be
absorbed.
E
C
Calculate from the “Absorbable
Servoamp Energy” diagrams.
5
Find the energy consumed by the regenerative
resistor.
E
K
E
K
= E
S
-- (E
L
+E
M
+E
C
)
6
Calculate the required regenerative resistor
capacity.
W
K
W
K
= E
K
/ (0.2
¢
T)
5
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