SERVO SELECTION AND DATA SHEETS
5.3.4
Starting Time and Stopping Time
240
5.3.4 Starting Time and Stopping Time
1) The motor starting time (tr) and stopping time (tf) under constant load are calculated by
the following formulas. The motor viscous torque and friction torque are ignored.
Starting Time:
Stopping Time:
tf
=
104.7
×
N
R
(J
M
+
J
L
)
K
t·
I
R
(
α
–
β
)
tf
=
104.7
×
N
R
(J
M
+
J
L
)
K
t
·I
R
(
α
+
β
)
[ms]
[ms]
N
R
: Motor rated speed (r/min.)
J
M
: Motor moment of inertia (kg
¡
m
2
=lb
¡
in
¡
s
2
)
(GD
2
M
/4)
. . .
J
L
: Load converted to shaft moment of inertia (kg
¡
m
2
)
(GD
2
L
/4)
. .
K
t
: Motor torque constant (N
¡
m/A=lb
¡
in/A)
I
R
: Motor rated current (A)
α=
I
P
/I
R
: Accel/decel current coefficient
[where I
P
is accel/decel current (accel/decel current is
α
times the motor rated current) (A)]
β=
I
L
/I
R
]: Load current coefficient
[I
L
]: Load torque equivalent current (load current is
β
times the motor rated current) (A)]
Motor Current
Time
Motor Speed
Motor Current (size) - Motor Speed Timing Chart
Time
5
