• 20 • Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 0105-E
NOTE :
An under-tensioned belt will slip, heat and wear prematurely. On the other hand, if a belt is over-
tensioned, the pressure on the bearings will cause them to over-heat and wear prematurely. Incorrect
alignment will also cause the belts to wear prematurely.
9a)PULLEYS ALIGNMENT
After adjusting one or both of the pulleys, check the transmission alignment using a ruler placed on the inner
face of the two pulleys.
NOTE: The warranty may be affected if any major modification is made to the transmission without
obtaining our agreement beforehand.
The actual resistance of ductwork systems is not always identical to the calculated theoretical values. To rectify
this, it may be necessary to modify the pulley and belt setting. To this effect, the motors are fitted with variable
pulleys.
9b)AIRFLOW BALANCING
Measure the absorbed amps
If the absorbed amps are greater than the rated values, the ventilation system has a lower pressure drop than
anticipated. Reduce the flow by reducing the rpm. If the system resistance is significantly lower than design,
there is a risk that the motor will overheat resulting in an emergency cut out.
If the absorbed amps are lower than the rated values, your system has a higher pressure drop than anticipated.
Increase the flow by increasing the rpm. At the same time you will increase the absorbed power which may result
in having to increase the motor size.
9c)CHECKING AIRFLOW AND ESP
Using the following fan curve, the airflow, the total pressure available (P
TOT
) and the corresponding dynamic
pressure (Pd) can be estimated, for a specific operating point.
10) Before making any electrical connections, check that insulation resistance between power supply connection
terminals is in keeping with applicable regulations. Check the insulation of all electrical motors using a DC 500V
megohmeter, following the manufacturer’s instructions.
CAUTION: Do not start any motor whose insulation resistance is lower than 2 mégaohms.
Never start any motor while the system is under a vacuum.
PRELIMINARY CHECKS
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