Maico DAD 63/4 Montage- Und Betriebsanleitung Seite 22

16 Fault rectification
Difficulty starting the fan
Cause 1: Inadequate supply voltage.
Measure: Check data on rating plate.
Cause 2: Fuses not suitable for start-up condi-
tions.
Measure: Replace.
Cause 3: Incorrect assessment of moment of in-
ertia and connector components.
Measure: Re-calculate moments of inertia and fit
fan with a new motor if required.
Excessive power consumption (above value
stated on rating plate).
Cause 1: Excessive speed.
Measure: Replace motor and/or resize system.
Cause 2: Air density higher than stated in the pro-
ject data.
Measure: Replace motor and/or disc and/or res-
ize system.
Cause 3: Fan running at too high a pressure.
Measure: Resize the system or change the fan
type.
Cause 4: Motor running at below the normal
speed.
Measure: Check supply voltage and correct if ne-
cessary. Check winding for defects and repair or
replace if necessary.
Inadequate pressure
Cause 1: Throughput is higher than stated in the
project data as a result of the wiring being rated
incorrectly and/or temperatures other than those
planned for.
Measure: Change gear ratios and/or replace fan,
replace or adapt wiring.
Cause 2: Impeller damaged.
Measure: Check impeller and replace if neces-
sary.
Air pulsations
Cause 1: Fan running at throughput values close
to zero.
Measure: Change wiring and/or replace fan.
Cause 2: Unstable flow, blockage or poor intake
connection result in unstable air inlet conditions
(swirl).
Measure: Use deflectors to rearrange the intake,
clean and/or reconstruct intake.
22
Cause 3: Flow alternates between detaching from
and re-attaching to the walls of a diverging chan-
nel.
Measure: Rearrange the wiring and/or replace
fan.
Power drop after acceptable operating period
Cause 1: Leaks in channel upstream of fan.
Measure: Check channel and re-establish initial
conditions.
Cause 2: Impeller damaged.
Measure: Check impeller and replace if neces-
sary.
The air being transported, mechanical parts,
electrical noises etc. are causing excessive
noise.
Cause 1: Too high a speed is needed to achieve
the desired output.
Measure: Use sound-absorbing housing and/or
sound absorber. Replace fan with a model with
larger dimensions and the same output or with a
lower peripheral speed.
Cause 2: Impeller scraping on housing.
Measure: Check and, if necessary, correct install-
ation position of impeller and cables.
Cause 3: Bearings worn.
Measure: Check condition of bearings; if neces-
sary lubricate or replace.
Cause 4: Rotor and stator not positioned cent-
rally.
Measure: Check coaxiality; if necessary re-estab-
lish or replace electric motor.
Cause 5: Vibrations in the winding.
Measure: Can be reduced by using higher quality
motors.
Cause 6: Installation in resonant surroundings.
Measure: Reposition fan or use sound-absorbing
housing.
Excessive vibrations
Cause 1: Rotating parts imbalanced.
Measure: Check balance of impeller and, if ne-
cessary, restore to the prescribed values. Check
alignment of drive and/or balance of washers.
Check that shafts are straight.
Cause 2: Installation structure unsuitable: its nat-
ural frequency is close to the fan's speed.
Measure: Use weights to increase and/or change
natural frequency of installation structure.
Cause 3: Screw connections too loose.