YASKAWA USAREM-A5A Bulletin page 16

4. CHARACTERISTICS
4. 1 OVERLOAD CHARACTERISTICS
T h e o v e r l o a d p r o t e c t i v e c i r c u i t b u i l t i n SERVOPACK
p r e v e n t s t h e m o t o r a n d S E R V O PA C K f r o m o v e r -
l o a d i n g a n d r e s t r i c t s t h e a l l o w a b l e c o n d u c t i o n
time o f S E R V O PA C K . ( S e e F i g . 4 . 1 . )
I f t h e a l l o w a b l e p o w e r - o n t i m e d u r i n g m o t o r
l o c k i n g i s m a x i m u m , t h e h i g h e r t h e m o t o r s p e e d
i s , t h e q u i c k e r t h e m o t o r r e s p o n c e t o t h e s a m e
o v e r l o a d .
T h e o v e r l o a d d e t e c t i o n l e v e l i s s e t p r e c i s e l y
b y t h e h o t s t a r t c o n d i t i o n s a t a n a m b i e n t t e m -
p e r a t u r e o f 5 5 ° C a n d c a n n o t b e c h a n g e d .
NOTE
Hot start i s t h e overload characteristics when t h e
SERVOPACK is running at the rated load and thermally
saturated
1000
100
OPERATING
TIME
(s)
10
N= 3000 r/min
(AT RATED
\ SPEED )
1
0 7100
MOTOR RATED CURRENT (%)
Fig 4 1 O v e r l o a d Characteristics
N=0 r/mun
(AT MOTOR
\LOCK
200 3 0 0
4. 2 STARTING AND STOPPING TIME
T h e s t a r t i n g t i m e a n d s t o p p i n g t i m e o f S E R V O -
MOTOR u n d e r a c o n s t a n t l o a d i s s h o w n b y t h e
f o r m u l a b e l o w. V i s c o u s o r f r i c t i o n t o r q u e o f
t h e m o t o r i s d i s r e g a r d e d .
S t a r t i n g T i m e :
NR ( h i +
t r = 1 0 4 . 7 x
Kt h t ( a - /3)
S t o p p i n g T i m e :
NR (JM
tf= 104. 7 x ( m
Kt I R ( a -t-fl)
Where,
NR R a t e d m o t o r s p e e d ( r / m i n )
JM : M o t o r i n e r t i a o f m o t o r ( k g . m 2 x 1 0 - 4 = lb•1n2)
JL : M o m e n t o f i n e r t i a o f m o t o r ( kg • m2 x10-4= l b . in2 )
Kt: T o r q u e c o n s t a n t o f m o t o r ( N • m / A )
tit : M o t o r r a t e d c u r r e n t ( A )
= I r //R : A c c e l / d e c e l c u r r e n t c o n s t a n t
I r .
A c c e l / d e c e l c u r r e n t ( A c c e l / d e c e l c u r r e n t cr
times t h e m o t o r r a t e d c u r r e n t ) ( A )
=
IL /IR : L o a d c u r r e n t c o n s t a n t
C u r r e n t e q u i v a l e n t t o l o a d t o r q u e
IL :
(Load c u r r e n t /3 t i m e s t h e m o t o r r a t e d
c u r r e n t ) ( A )
MOTOR
ARMATURE
CURRENT
MOTOR!
SPEED
Fig. 4 . 2 Ti m i n g Chart of
Motor Armature Current and Speed
(Constant Load)
( ms)
s )
TIME
TIME