User Manual
800-543-9038 USA 866-805-7089 CANADA 203-791-8396 LATIN AMERICA
61
I
nsta
ll
at
i
on
I
nstruct
i
on
s
Electrical
Op
eratio
n
General
T
he AF series actuators utilize brushless DC motor technolo
g
y. The AF uses this
m
otor in con
j
unction with an Application
S
pecific Inte
g
rated
C
ircuit
(
A
S
I
C)
. In the
O
n
/
Off versions of the AF, the ASIC monitors and controls the actuator’s rotation and a
d
igital rotation sensing function to prevent damage to the actuator. The AF24…
m
odulating type actuators incorporate a built in microprocessor. The microprocessor
provides the intelligence to the ASIC to provide a constant rotation rate and knows
t
he actuator’s exact zero position.
Brushless DC Motor Operation
B
elimo’s brushless DC motor spins by reversing the poles of stationary
e
lectromagnets housed inside o
f
a rotating permanent magnet. The electromagnetic
poles are switched by a special ASIC circuit developed by Belimo. Unlike the
c
onventional D
C
motor, there are no brushes to wear or commutators to foul.
Overload Protection
T
he AF series actuators are protected
f
rom overload at all an
g
les o
f
rotation. The
A
A
SIC circuit constantly monitors the rotation of the DC motor inside the actuator and
stops the pulses to the motor when it senses a stall condition. The DC motor
remains energized and produces full rated torque to the load. This helps ensure that
d
ampers are fully closed and that edge and blade seals are always properly
c
om
p
ressed.
Motor Position Detection
B
elimo brushless DC motors eliminate the need for potentiometers for positioning in
m
odulating type actuators. Inside the motor are three “Hall E
ff
ect” sensors. These
sensors detect the spinnin
g
rotor and send pulses to the microprocessor which
c
ounts the
p
ulses and calculates the
p
osition to within 1/3 of a revolution of the
m
o
t
or.
Control Accuracy and Stability
A
F24-
S
R U
S
actuators have built-in
brushless DC motors which provide
better accuracy and longer service life.
The AF24-SR US actuators are designed with a unique non-symmetrical dead
-
b
and. The actuator follows an increasing or decreasing control signal with a
80 mV resolution. I
f
the signal changes in the opposite direction, the actuator
w
ill
not respon
d
unt
il
t
h
e contro
l
s
i
gna
l
c
h
anges
b
y 200 m
V
.
Thi
s a
ll
ows t
h
ese
a
ctuators to trac
k
even t
h
e s
li
g
h
test
d
ev
i
at
i
on very accurate
l
y, yet a
ll
ow
i
ng
the actuator to “wait”
f
or a much lar
g
er chan
g
e in control si
g
nal due to control
s
ignal instability
.
M40024 - 05/10 - Subject to change. © Belimo Aircontrols (USA), Inc
.