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44
Installation Instructions
Electrical Operation
General
The EFB, EFX series actuators utilize both DC Motors and brushless DC motor
technology. The EFB, EFX uses this motor in conjunction with an Application Specific
Integrated Circuit (ASIC). In the On/Off versions of the EFB and EFX, the ASIC
monitors and controls the actuator’s rotation and a digital rotation sensing function
to prevent damage to the actuator. The EFB24, EFX24… modulates type actuators
incorporate a built in microprocessor. The microprocessor provides the intelligence
to the ASIC to provide a constant rotation rate and knows the actuator’s exact zero
position.
Brushless DC Motor Operation
Belimo’s brushless DC motor spins by reversing the poles of stationary
electromagnets housed inside of a rotating permanent magnet. The electromagnetic
poles are switched by a special ASIC circuit developed by Belimo. Unlike the
conventional DC motor, there are no brushes to wear or commutators to foul.
Overload Protection
The EFB, EFX series actuators are protected from overload at all angles of rotation.
The ASIC 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
dampers are fully closed and that edge and blade seals are always properly
compressed.
Motor Position Detection
Belimo brushless DC motors eliminate the need for potentiometers for positioning in
modulating type actuators. Inside the motor are three “Hall Effect” sensors. These
sensors detect the spinning rotor and send pulses to the microprocessor which
counts the pulses and calculates the position to within 1/3 of a revolution of the
motor.
Control Accuracy and Stability
-SR and MFT EF actuators have built-
in brushless DC motors which provide
better accuracy and longer service life.
The -SR and MFT EF actuators are designed with a unique non-symmetrical
deadband. The actuator follows an increasing or decreasing control signal
with a 80 mV resolution. If the signal changes in the opposite direction, the
actuator will not respond until the control signal changes by 200 mV. This
allows these actuators to track even the slightest deviation very accurately, yet
allowing the actuator to “wait” for a much larger change in control signal due
to control signal instability.
8
8
EF
EF
Note:
Resolution is a percentage of operating range. 1% in one direction,
2.5% when changing direction. 2-10 VDC control example shown above.
N40103 - 09/11 - Subject to change.
© Belimo
Aircontrols (USA),
Inc.
