YASKAWA USAREM-A5A Bulletin page 17

4. 3 ALLOWABLE FREQUENCY OF OPERATION
T h e a l l o w a b l e f r e q u e n c y o f o p e r a t i o n i s r e s t r i c t e d
b y t h e S E RV O M O TO R a n d S E R V O PA C K , a n d t h e
c o n d i t i o n s m u s t b e c o n s i d e r e d f o r s a t i s f a c t o r y
o p e r a t i o n .
A l l o w a b l e f r e q u e n c y o f o p e r a t i o n r e s t r i c t e d b y
t h e S E R V O PA C K
T h e a l l o w a b l e f r e q u e n c y o f o p e r a t i o n i s r e -
s t r i c t e d b y t h e h e a t g e n e r a t e d i n t h e r e g e n -
e r a t i v e r e s i s t o r i n t h e S E R V O PA C K , a n d v a r i e s
d e p e n d i n g o n t h e m o t o r t y p e s , c a p a c i t y , l o a d
GD2 , a c c e l e r a t i o n / d e c e l e r a t i o n c u r r e n t v a l u e s ,
and m o t o r s p e e d . I f t h e f r e q u e n c y o f o p e r a -
t i o n e x c e e d s 6 0 t i m e s /min w h e n l o a d i n e r t i a J r ,
(GD2L) b e f o r e t h e m o t o r becomes r a t e d s p e e d ,
o r i f i t e x c e e d s m 6 + 0 1 c y c l e s / m i n w h e n l o a d
i n e r t i a J L (GD2L) = m o t o r i n e r t i a J M (GD2M) x m ,
c o n t a c t y o u r YA S K A W A r e p r e s e n t a t i v e .
A l l o w a b l e f r e q u e n c y o f o p e r a t i o n r e s t r i c t e d b y
t h e S E RV O M O TO R
T h e a l l o w a b l e f r e q u e n c y o f o p e r a t i o n v a r i e s
d e p e n d i n g on t h e load c o n d i t i o n s , m o t o r r u n n i n g
time a n d t h e o p e r a t i n g c o n d i t i o n s . T y p i c a l
examples a r e s h o w n b e l o w. S e e P a r . 4 . 2 , " S t a r t i n g
a n d S t o p p i n g T i m e " f o r s y m b o l s .
When t h e m o t o r r e p e a t s r a t e d - s p e e d o p e r a t i o n
and b e i n g a t s t a n d s t i l l ( F i g . 4 . 3 ) .
C y c l e t i m e ( T ) s h o u l d b e d e t e r m i n e d s o t h a t
RMS v a l u e o f m o t o r a r m a t u r e c u r r e n t i s l o w e r
t h a n t h e m o t o r r a t e d c u r r e n t :
T. 1 p 2 ( t r + t f ) + I f t s
/ R 2
Where c y c l e t i m e ( T ) i s d e t e r m i n e d , v a l u e s
I p , t r , t f s a t i s f y i n g t h e f o r m u l a a b o v e , s h o u l d
be s p e c i f i e d .
MOTOR
ARMATURE
CURRENT
MOTOR I
SPEED
Fig 4 . 3 Ti m i n g Chart of
Motor Armature Current and Speed
(Restricted by SERVOMOTOR)
( s )
TIME
TIME
When t h e m o t o r r e m a i n s a t s t a n d s t i l l b e t w e e n
c y c l e s o f a c c e l e r a t i o n a n d d e c e l e r a t i o n w i t h o u t
c o n t i n u o u s r a t e d s p e e d r u n n i n g ( F i g . 4 . 4 ) .
T h e t i m i n g c h a r t o f t h e m o t o r a r m a t u r e c u r -
r e n t a n d s p e e d i s a s s h o w n i n F i g . 4 . 4 . T h e
allowable f r e q u e n c y o f o p e r a t i o n " n " c a n b e
c a l c u l a t e d a s f o l l o w s :
Kt • I R
n=286.5 x
N R G r A i
MOTOR
ARMATURE
CURRENT
MOTOR
SPEED
Fig 4 4 Ti m i n g Chart of
Motor Armature Current and Speed
'The motor remains at standstill between
cycles of accel/decel without continuous
`rated speed running
When t h e m o t o r a c c e l e r a t e s , r u n s a t c o n s t a n t
speed, a n d d e c e l e r a t e s i n a c o n t i n u i n g c y c l e
w i t h o u t b e i n g a t s t a n d s t i l l ( F i g . 4 . 5 ) .
The t i m i n g c h a r t o f t h e m o t o r a r m a t u r e
c u r r e n t a n d s p e e d i s a s s h o w n i n F i g . 4 . 5 .
The a l l o w a b l e f r e q u e n c y o f o p e r a t i o n " n " c a n
be c a l c u l a t e d a s f o l l o w s .
Kt •
n= 286. 5 X N R ( J m + J D
MOTOR
ARMA TURE
CURRENT
MOTOR 1
SPEED
Fig 4 . 5 Ti m i n g Chart of
Motor Armature Current and Speed
[The motor accelerates, runs at constant speed,
and decelerates in a continuing cycle without be-
ing at standstill
( 1 f i ' 2 \
+ h i a a 3
(times / m i n )
TIME
TIME
I R ( 1 # 2 \
a a )
(times /min)
TIME
TIME