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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
Wire Size Max. Feet. Wire Size Max. Feet
12 Ga 900 Ft. 18 Ga 225 Ft.
14 Ga 550 Ft. 20 Ga 125 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, and AF24-MFT 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. The AF24-MFT US will also return to
its position prior to the 20-second-or-less power loss. 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
K20901 - 01/09 - Subject to change. © Belimo Aircontrols (USA), Inc.
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