YASKAWA VS-626M5, Instruction Manual, Page: 290 / 305

Appendix
15.3.4 Intermittent Load Operating Capacity
1 5 -18
15.3.4 Intermittent Load Operating Capacity
If operations, such as tapping a machine-tool or driving a conveyer table, are frequently reversed, care must
be taken in selecting the capacity. When using an operation cycle that includes acceleration/deceleration
operations such as those shown in Fig. 15.19, make a selection so that the motor equivalence efficiency
torque T
R
is less than the inverter continuous rated torque. (The maximum value of T
P
will be 120% of
the Inverter 30 min. rating.)
T
R
= (N
•
m)
T
P
2 (
t
r
+
t
f
) +
T
L
2
t
s
t
C
Motor torque
Motor speed
t
r
t
c
t
s
T
L
T
P
− T
P
N
M
Time
Time
t
f
Fig 1 5 . 19 Motor Torque and Speed Timechart
The motor reverse rating is the rating over the load where the motor load changes cyclically. When the
reverse rated output is taken to be t
1
, and with no load is taken to be t
2
, a as expressed in the following
formula is called %ED (Einschalt Dauer).
t
1
+
t
2
is regulated to 10 minutes.
α
=
t
1
t
1
+
t
2
×
100
(%)
15