In addition, the actual power consumption of all phases’ shall be measured and compared with the
nameplate. If the actual power consumption is too high, there is maybe a faulty connection. The
system must be shut down immediately.
Measure the volume flow and the pressure difference. Often the measured airflow does not match
with the design data of the device.
Two cases can occur:
The airflow is too low
-
The reason is that the external pressure drop is higher than indicated on the technical data
sheet.
-
Remedy: By replacing or adjusting the pulleys the airflow can be increased.
-
Attention! Increase the fan speed only to the extent that the motor rated current is not exceed-
ed. If this is not enough only the motor replace helps.
The airflow is too high
-
The reason is, that the external pressure drop is less then indicated in the technical data sheet.
-
Result: The electrical absorbed power rises sharply.
-
Attention! Possible motor damage due to overload.
-
Remedy: Either change or adjust pulleys to reduce fan speed or reduce airflow by closing a
damper partially.
Adjusting variable pulleys
Figure 125:
Smallest working diameter
Figure 126:
Biggest working diameter
