RAS 74.40 - Page 214

ANALOGUE
REGUI-ATION
ELECTRONICS
REG-3
9.6.4.
COMMUTATION
LIMIT
The commutotion
limit
hos io
be respected
when using
direct
current
motors
with
o
permonent
excitqtion (no
field)
ond
iron
core, The
limiting
curve of
the
suitoble
motor
current
dependont
on speed,
is
indicoted in
the doto sheets
for motors
Concerning
motors,
the
moximum
torque,
which corresponds
to
ihe moximum
current,
comes
up to
3 to 6 tlmes the
vqlue
of the
constont
torque,
lt is double
the
volue with
servo-ompllflers.
Toke this
mofor
curve
here os on
3xlnenn
exomple,
The lineor
limit
choroc-
teristic
of the servo-ompllfier
must
be
within
the
motor chorocteristic.
The
li-
miting
line
for omplifiers is
morked
qt
2x lnenn
(which
corresponds
to l0
V
nominol
current volue),
The
stroight
reduction
line is
then
ploced
tongen-
tiolly to
the
motor chorocteristic.
The
stroight
line
is defined
os
S=V/7on
volue
S
=
V
eurrent
chonge
/
,
%
t:era.ue
chonge
I nenn
Rlta
ltol
The
volues
for the
exomple
given
ore
d5 tra
-<
s
(v/z^)
insertion
point
=
50 %
speed
slope
=
6/50
=
0,.l2 Yl"/on
The
option
commutotion
limit
is
set
with
the resistonces
Rl I I
ond Rl
.l2,
At first
the resistonce
Rl l2
for
the slope
is fixed,
then ihe
resistonce
Rl I I
for the insertion
point
is derivoted,
Rll
lko
Einsotzpunkt
Exomple:
Rl
12
=
220
kA
Rill
=8,2ko
The
odjustment con
be controlled
by introducing
o
direct current
volt-
oge which
corresponds
to the
tochometer
voltoge
of
the
tocho-
meter input
ond
by
meosuring
the
reduction
of
the nominol
current
vo-
lue
ot X4:.l5
(10
V
=
2x
lnenn),
The volues
ore
good
for
o
nominql
vqlue
of
l0 V,
.B
!a
E
tr
50'/-
l00Z Dnehzoht
Ste{hcrt
OJ
t0
e0 30
{0
!0 60 70
g0
90 r00 h
I
rl
rl
t5
ta
l3
lt
t0
9
I
I
6
a
3
?
I
0
-)n-
llNlTtrK lndrretrio
Flalzlrnnilz
GmFrU
lAriiniaaara+raD
^
o
-
h
?{ 44, l^n;6^-i^^ , Oa..s--r A
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