YASKAWA USAREM-A5A Bulletin page 30

6. 3 EXTERNAL CURRENT LIMIT REFERENCE
CIRCUIT [P-CL, N-CL]
C u r r e n t can be limited f r o m t h e outside
as within SERVOPACK. T h e external
limit is used f o r the following cases:
To p r o t e c t t h e m o t o r f r o m o v e r l o a d c u r r e n t
when a n a b n o r m a l l o a d l o c k o c c u r s i n t h e
load.
• T o c h a n g e t h e c u r r e n t l i m i t v a l u e a c c o r d i n g
to t h e e x t e r n a l sequence.
The c u r r e n t c a n b e l i m i t e d b y m u l t i -stage
setting b y t h e u s e o f r e l a y s ( F i g . 6 . 6 ) . T h e
same e f f e c t c a n b e o b t a i n e d b y g i v i n g v o l t a g e
signals making analog change.
CONSTANTt
VOLTAGE ,
SUPPLY
Relay L o w - l e v e l relay type G2A-432A made by OMRON
Fig 6 6 Multi-stage Switching of
Current Value at Forward Side
6 3 1 Method for Giving External Current
Limit Reference
Forward c u r r e n t a n d r e v e r s e c u r r e n t c a n b e
controlled i n d e p e n d e n t l y. T h e f o r w a r d c u r r e n t
can b e c o n t r o l l e d b y g i v i n g a r e v e r s e v o l t a g e
(0 t o - 9 . 0 V) between SERVOPACK terminals 1CN-
0 a n d © ; t h e r e v e r s e c u r r e n t c a n b e c o n -
trolled b y a f o r w a r d v o l t a g e ( 0 t o + 9 . 0 V )
between terminals 1CN - 8 a n d
The r e l a t i o n b e t w e e n t h e r a t e d c u r r e n t o f
the motor a n d c u r r e n t l i m i t values i s r a t e d c u r -
rent a t 3 . 0 V f o r applicable m o t o r. T h e p o w e r
supply must use a n i n t e r n a l resistance less t h a n
2k G. T h e i n p u t r e s i s t a n c e a t SERVOPACK side
must b e g r e a t e r t h a n 5 k n . W h e n e x t e r n a l c u r -
r e n t i s n o t r e s t r i c t e d , c o n t a c t s between t e r m i -
nals 1 C N - ( 3 a n d 0
and Q a r e opened.
6 3. 2 Set Voltage and Current Limit Values
The r e l a t i o n s h i p b e t w e e n s e t v o l t a g e s o f 0 t o
±9.0 V a n d c u r r e n t l i m i t v a l u e s a r e s h o w n i n
Fig. 6 . 7 .
as well
current
SERVOPACK
-44
Q
a n d between 1 C N -
— 23 —
300
200
CONTINUOUS
CURRENT
RATIO
(%)
100
O (APPROX \ -3
k -06V )
(a) Current Limit at Forward Side
300
CONTINUOUS 2 0 0
CURRENT
RATIO
(%)
100
O ( A P P R O X \ 3
\ — 0 6 V I
(b) Current Limit at Reverse Side
Note I f setting value exceeds max output current value of servopock.
max output current value becomes saturation value
Fig 6 7 S e t Voltage and Current Limit Values
6 3 3 Current Limit when Motor is Locked
When l o c k i n g a m o t o r b y a p p l y i n g a c u r r e n t
limit, d e t e r m i n e a c u r r e n t l i m i t v a l u e l e s s t h a n
the r a t e d c u r r e n t o f t h e motor. I f t h e load condi-
tion r e q u i r e s a c u r r e n t l i m i t exceeding t h e r a t e d
motor, c u r r e n t , r e f e r to P a r. 6 . 5 ( 3 ) , " O v e r l o a d
detection level" a n d make s u r e t o u n l o c k t h e
motor before reaching t h e t r i p level.
Note t h a t w h e n t h e s p e e d r e f e r e n c e v o l t a g e
is less t h a n t e n s o r s o millivolts(affected by s e t -
ting o f G A I N [LOOP ) , t h e m o t o r l o c k c u r r e n t
sometimes p u l s a t e s . I f t h i s i s n o t d e s i r a b l e ,
the c u r r e n t p u l s a t i o n c a n b e r e m o v e d b y i n -
creasing t h e speed reference v o l t a g e .
- 6
-9
SET VOLTAGE (V)
9
6
SET VOLTAGE (V)