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Figure 10. CNA 250-400/D and CNB 400/D
CNA & CNA-M, 500, -630/D and
CNB & CNB-M, 500, -630/D (See fig. 11)
The motor is mounted on a motor brack-
et which is mounted on a conical cover in
the back plate of the fan casing.
Dismount the motor by removing both
bracket and conical cover from the fan
casing. After that withdraw the impeller
from the motor shaft and remove the
cover, then remove the motor from the
motor bracket.
Figure 11. CNA 500 & 630/D &
CNB 500 & 630/D
6.9 Fault localization
Deficiency in performance
– Blocked air supply on fan inlet side
– Damper closed
– Duct choked
– Installation conditions resulting in
poor air flow to impeller
– Impeller has wrong direction of rota-
tion
– Motor defective
– Motor cut out
Noise/vibrations
– Bearings in motor or bearing assem-
bly defective
– Impeller out of balance
– Impeller worn/damaged
– Loose screws/components
– Impeller has wrong direction of rota-
tion
7. Sound
The sound generation of the fan depends
on installation and operating conditions
which means that no general data of the
sound generation can be given. Refer-
ence is made to our catalogues or PC pro-
grams for calculation of the specific
sound generation.
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