Yaskawa Varispeed 626M5 - Manual (Page 290)

Appendix
15.3.4 Intermittent Load Operating Capacity
15 -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 15.19 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