Yaskawa Varispeed 626M5 - Manual (Page 127)

Wide Constant Power Control Using Winding Selection
7 -4
7.3 Motor Characteristics
Motors with switchable windings with a 1:12 constant power range have a 1:4 constant power range for both
the low-speed and high-speed windings, as shown in the following diagram.
This can be written as S
ML
/S
BL
= S
MH
/S
BH
= 4. Also, the base speed ratio and maximum speed ratio are set
to S
BH
/S
BL
= S
MH
/S
ML
= 3 to optimize the motor characteristics.
Consequently, the rated output will occur for both the low-speed and high-speed windings between S
BH
and
S
ML
, so winding selection is performed within this speed range.
(If the same output occurs in both the low-speed and high-speed coils between S
BH
and S
ML
, the load factor
meter signal may be off by approximately ±10%.)
Low-speed Winding Application Precautions
The characteristics cannot be assured if the low-speed winding speed range exceeds S
ML
, so avoid excessive
use.
Speed
Rated output range
Low-speed coil range
High-speed winding range
Winding selection range
1.0
0 0.083
0.33
S
BL
S
ML
(P.U)
(P.U)
S
B S
M
S
MH S
BH
1.0
0
(P.U)
0.25 1.0
High-speed
winding
output
Low-speed
winding
output
Fig 7.2 Motor Output Characteristics
7
IMPORTANT