GUIDELINES FOR INSTALLING the AVA series of VSD controllers
How does the controller work? Fantech single phase controllers vary available power to the load using phase angle conduction control. As the conduction angle is reduced, the
power to the load is reduced. This reduction is accompanied by a reduction in the AC voltage across the load and can be used as an indicator of the power change or calibration
reference. In resistive, transformer, universal motor and shaded pole motor applications, the main output is used. For PSC motors, either 2 or 3 wire control can be used. 3 wire has
separate outputs for the main and aux windings of the motor from the controller.
How effective and efficient? There is much to be said for keeping things simple! It is in this spirit that Fantech single phase controllers have been designed. There are no micro
controllers or sensitive electronic components – justsimple rugged commercially designed circuitry and industrially rated power components that can be protected using standard
MCB’s and fuses. There are many ways to vary power to AC loads. For resistive and transformer type inductive loads, Fantech Controllers are highly effective and very efficient
(~95%) . For universal brush type motors they are also efficient but for some motors minor “cogging” can occur at very low speed settings due to AC waveform and brush / commutator
being out of sync. For induction type capacitor run PSC motors using a permanent aux/ run capacitor, phase angle control is highly effective for loads where the torque requirements
changes with speed – eg fans and pumps. Efficiency is ~70% for the 2-wire method and can be >90% for 3-wire configurations & comparable to the more complex 3-phase variable
frequency V/F or inverter drives. The graph below shows typical power efficiencies for a single phase fan using std 3-speed windings, 2-wire and 3-wire control.
Motor considerations Phase angle conduction control is suitable for all types loads connected to universal (brush) or shaded pole motors. For PSC capacitor run motors there
are some criteria essential for successful speed control. If a reasonably linear change in speed is required, the motor mustbe suitable for speed control, it must be optimally sized for
the load and the load torque characteristics must change (increase) with speed. Fans and centrifugal pumps are ideal but high starting torque loads such as compressors or loads
whose torque does not change with speed, are not. Split phase and capacitor start capacitor run motors cannot be used with a speed control due to the startcircuit which is usually
motor speed dependant. Inefficient & poorly matched motor / load combinations are more difficult to speed control particularly where the motor is sized much larger than the load
requires.
Output Configurations The AVA can be connected in two different configurations. For transformer, resistive loads, shaded pole motors or universal (brush) motors, the output is
between Mm and Mc. For PSC motors there are two ways in which the motor may be wired. Generally the 2-wire is simplest and can be used for smaller motors <150W output power.
The 3-wire configuration involves connecting the main and auxiliary windings of the motor to different parts of the AVA controller. Three wires are thus involved – input, main output and
auxiliary output. The 3-wire is slightly more complex but for most motors offers better speed control over the range, higher efficiency, lower motor noise and lower motor temperature.
NB: For all Fantech fans, CMG motors and motors >200w, the 3-wire configuration MUST be used. The AVA series of VSD’s can individually control more than one motor (similar or
dissimilar) provided the maximum current of all motors does not exceed the maximum controller current.
Wiring For resistive loads and shaded pole / universal (brush) AC/DC motors use terminals Mm and Mc for the output. This is termed simple 2-wire control. Terminal Ma (ver D) is a
solid state 240 VAC output, uses zero voltage switching & cuts in slightly after the main output. This minimises switching surges and EMI. Terminal Ma in ver D controllers can also be
used for switching auxiliary loads ON/OFF - eg pilot lamps, shutters, contactor, aux motor windings – NB max total power of main and aux outputs must not exceed 100% of total
controller rated power.
For PSC (capacitor run) motors, there are 2 ways in which the motor may be wired to the controller. The 3-wire configuration requires disconnection of one side of the capacitor from
the main motor terminal & route this as the 3rd wire from the motor to the controller aux output – Ma. Fantech fan motors make this easy by removing the link between L1 & L2. L1
goes to Ma and L2 to Mm. On some motors the main, auxiliary and capacitor are wired in the neutral side with the common windings going to active. The mains input to the controller
may be connected either way around in terms of whether the active goes to~L or ~Lc. It is also acceptable to change the motor wiring to a common neutral – there is no difference.
CAUTION: Always isolate the controller / motor OFF via the feed MCB or isolator before working on any wiring. Be careful connecting cables to terminals. Make sure the opposite end
plate (adjusting potentiometers end), is in place and secure as it provides a mechanical end stop for the PCB. Divide individual cable cores evenly across each terminal spade. Tighten
terminals securely. Support back of connector with finger whilst tightening & pushing with a screwdriver. A slot screwdriver may provide better grip than a star or Phillips type.
Electromagnetic Compliance No additional snubbers or external suppressors are required. When properly installed, the AVA series of Fantech controllers meet the
Electromagnetic Compliance (EMC) requirements of Australia & New Zealand. Correct installation requires the Mm conductor between the controller and the load, be screened
(shielded), and that the screen be earthed at one point. Screening may be accomplished by enclosing all the cables between the controller and motor in an earthed screen or metal
conduit. If the motor and controller are installed within a common earthed metal chassis or are close together, then cable screening may not be necessary.
Earthing. The controller must be installed in accordance with AS3000:2000. Thecase of the controller is earthed through the separate external earth lug provided. Caution -
Screened output cable – the cross-sectionalarea of screening on a single screened cable may not be sufficient for it to act as an earth conductor.
Overload Protection. The AVA range is adequately rated for motor starting and a generous short term overload margin is provided for in its design. It is recommended that both
the load and controller are protected by a thermo-magnetic circuit breaker rated according to the motor or appliance manufacturer recommendations and/or local wiring regulations. As
a guide fit circuit breakers: AVA5.0 – 5 or 6 amp AVA8.0 – 8 amp AVA10.0 – 10 amp AVA15.0 – 15 amp AVA120 – 20 amp AVA130 – 30 amp.
Controller Fuse: The controller is fitted with a replaceable fuse just behind terminals A B C. If it blows, something is wrong with your wiring, installation or motor! To check, isolate OFF
then carefully prise out the fuse with a small screwdriver or long nose pliers. Only the following fuses should be used.
AVA5.0 6A slow blow (SB) / 7A fast blow (FB) AVA8.0 10A SB / 12A FB AVA10.0 12A SB / 15A FB AVA15.0 20A SB AVA120 25A SB AVA130 35A SB
When replacing the fuse make sure that the clips are a tight grasp onto the fuse. If not, gently squeeze them together to effect a firm grip on the fuse when it is inserted. Each clip has
an end stop and the fuse should be located centrally between the two opposite end stops. If a fuse blows, there is usually a serious problem that must be investigated & resolved.
Control Signal Screen. A control cable screen earthing point is provided near the terminals. This should be used with caution. Best practice is to earth the screen at one end only
and this ideally should be the source end. Do not earth both ends of a screened control cable as earth loops could result causing erratic control signal problems.
0
10
20
30
40
50
60
70
Relative Power Consumption VA
2400 2000 1600 1200
Fan Speed rpm
COMPARISON OF POWER CONSUMPTION FOR 3
DIFFERENT SPEED CONTROL CONFIGURATIONS
standard 3 speed switched windings 2 wire configuration 3 wire configuration
EBM R2E190.A062-39 fan
3 spd
2W
3W
Partno.INST‐AVAVSDADVICE August2012 Page3of5
