Fan Starter - Lennox BCK 020 Installation Operating & Maintenance Manual

VENTILaTION : FANSTART
AIR SOCK CONTROL
FANSTART OPERATION
The use of air socks for space conditioning allows high air
volumes to be distributed at low velocity and is becoming a
common feature in many applications. To accommodate this
trend, Air-sock control is offered which allows the air socks
to be progressively filled with air on start up. BALTIC has
been enhanced with an electronic device to soft start the
fan. It takes up to 1 minute to go from 0% of air to full air
flow.
This time can be divided in several stages:
- The aim of this first voltage input is to overcome the
resistance of the transmission (Pulleys and belts): 0.5s and
up to 1000 rpm
- The second stage is to inflate the air sock: 5 to 30s. and
600 to 900 rpm
Finally the air sock is gradually pressurised during the last 5
to 30 second. The motor reaches nominal speed and the
controller is bypassed.
Current
1 voltage Input to Overcome
st
transmission resistance
Over-current limit
Air sock
Inflation
5 to 30s Acceleration 15 to 30s
The motor speed control is achieve through a variation of
the supply voltage of each phase at constant frequency.
The thermal overload limit on the motor imposes a current
limitation during the acceleration stage. Hence if the
selected slope is to steep, a predefined current limit can be
reached (potentiometer adjustment) and the controller will
automatically reduce the voltage set-point accordingly. Then
once the current is back under the high current limit it
carries on with the start up cycle.
Safety
Excessive "slow down" limit
The FANSTART will display a fault (red LED) and stop the
motor, if the motor slows down excessively (voltage could
reach 0V) because of the current limitation during the
acceleration stage.
Missing phase safety
The FANSTART will display a fault (red LED) if the current
in the third phase is too low or reaches 0 Amps (Three
phase supply or motor problem)
Current protection of the Thyristor
The FANSTART will display a fault (red LED) if the current
exceeds the thyristor current limits
Start up sequence too long
A fault (red LED) will appear if after 1min20s the FANSTART
Control is not bypassed and the motor running from the
mains.
Phase rotation check
If the phase rotation is incorrect the FANSTART Control will
display a fault ( Red LED). Two of the phases must then be
inverted and the start up cycle resumed.
Fig. 42
FAN START
Power + Control ON
FANSTART off
125A during 0.4s
87.4A during 2s
75A during 6s.
62.5A during 20s.
MOTOR OFF
OFF
Green LED = 0
Red LED = 0
Control ON
Green LED = 1
Power OFF
Red LED = 0
PHASE
ROTATION
NOT OK
CHECK
OK
INFLATION I > I max
Speed = 0
Green LED = 1
T > 1 min20s
Red LED = 0
I < Imin
ACCELERATION
I > I max
Green LED = 1
Speed = 0
Red LED = 0
T > 1 min20s
(If current control ON)
I < Imin
CONTROL OFF
motor connected
to mains
IOM / ROOFTOP BALTIC Series - 0803 - E Page 41
MOTOR OFF
Green LED = 1
Red LED = 1
T°C Fault
Thyristor
Fig. 43