AERCO Belimo AF120-S US Actuator - Manual (Page 8)

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WARNING The wiring technician must be trained and experienced with electronic
circuits. Disconnect power supply before attempting any wiring connections or
changes. Make all connections in accordance with wiring diagrams and follow all
applicable local and national codes. Provide disconnect and overload protection as
required. Use copper, twisted pair, conductors only. If using electrical conduit, the
attachment to the actuator must be made with flexible conduit.
Always read the controller manufacturer's installation literature carefully
before making any connections. Follow all instructions in this literature. If you
have any questions, contact the controller manufacturer and/or Belimo.
Transformers
The AF24 . . actuators require a 24 VAC class 2 transformer and draws a maximum
of 10 VA per actuator. The actuator enclosure cannot be opened in the field, there
are no parts or components to be replaced or repaired.
– EMC directive: 89/336/EEC
– Software class A: Mode of operation type 1
– Low voltage directive: 73/23/EEC
CAUTION: It is good practice to power electronic or digital controllers from a
separate power transformer than that used for actuators or other end devices. The
power supply design in our actuators and other end devices use half wave
rectification. Some controllers use full wave rectification. When these two different
types of power supplies are connected to the same power transformer and the DC
commons are connected together, a short circuit is created across one of the diodes
in the full wave power supply, damaging the controller. Only use a single power
transformer to power the controller and actuator if you know the controller power
supply uses half wave rectification.
Multiple Actuators, One Transformer
Multiple actuators may be powered from one transformer provided the following rules
are followed:
1. The TOTAL current draw of the actuators (VA rating) is less than or equal to the
rating of the transformer.
2. Polarity on the secondary of the transformer is strictly followed. This means that
all No. 1 wires from all actuators are connected to the common leg on the
transformer and all No. 2 wires from all actuators are connected to the hotleg.
Mixing wire No. 1 & 2 on one leg of the transformer will result in erratic operation
or failure of the actuator and/or controls.
Multiple Actuators, Multiple Transformers
Multiple actuators positioned by the same control signal may be powered from
multiple transformers provided the following rules are followed:
1. The transformers are properly sized.
2. All No. 1 wires from all actuators are tied together and tied to the negative leg of
the control signal. See wiring diagram.
Wire Length for AF... Actuators
Keep power wire runs below the lengths listed in the Figure H. If more than one
actuator is powered from the same wire run, divide the allowable wire length by the
number of actuators to determine the maximum run to any single actuator.
Example:
3 actuators, 16 Ga wire
350 Ft ÷ 3 Actuators = 117 Ft. Maximum wire run
MAXIMUM WIRE LENGTH FOR 10VA
Wire Size Max. Feet. Wire Size Max. Feet
12 Ga 900 Ft. 18 Ga 220 Ft.
14 Ga 550 Ft. 20 Ga 120 Ft.
16 Ga 350 Ft. 22 Ga 60 Ft.
FIGURE H
Wire Type and Wire Installation Tips
For most installations, 18 or 16 Ga. cable works well with the AF24... actuators. Use
code-approved wire nuts, terminal strips or solderless connectors where wires are
joined. It is good practice to run control wires unspliced from the actuator to the
controller. If splices are unavoidable, make sure the splice can be reached for
possible maintenance. Tape and/or wire-tie the splice to reduce the possibility of
the splice being inadvertently pulled apart.
The AF24... proportional actuators have a digital circuit that is designed to ignore
most unwanted input signals (pickup). In some situations the pickup may be severe
enough to cause erratic running of the actuator. For example, a large inductive load
(high voltage AC wires, motors, etc.) running near the power or control wiring may
cause excessive pickup. To solve this problem, make one or more of the following
changes:
1. Run the wire in metallic conduit.
2. Re-route the wiring away from the source of pickup.
3. Use shielded wire (Belden 8760 or equal).
Ground the shield to an earth ground.
Do not connect it to the actuator common.
Initialization of the AF24-SR US
When power is initially applied, the actuator will first release its manual preload
position (This assumes a manual position has been set). The actuator will then rotate
to the full fail-safe position. At this point the microprocessor recognizes that the
actuator is at full fail-safe and uses this position as the base for all of its position
calculations. The microprocessor will retain the initialized zero during short power
failures of up to 20 seconds. For power failures greater than 20 seconds, the actuator
would naturally return to its full fail-safe position prior to the microprocessor losing
its memory. The actuator will also re-initialize if the manual position mechanism is
used.
Installation Instructions
General Wiring Instructions
M40024 - 05/10 - Subject to change.
© Belimo
Aircontrols (USA),
Inc.