12
POSSIBLE MALFUNCTIONS AND THEIR ELIMINATION
Problem
Possible reasons
Elimination
The fan will not start.
No power supply.
Check the mains switch. Check the electrical connections
against the wiring diagram.
Jammed motor.
Carefully check the fan impeller for possible seizure and
eliminate it, if necessary. If the impeller is in order, replace
the electric motor.
The switching equipment
activates upon fan start-up.
Short circuit in the fan or the electric circuit between
the fan and the switching equipment.
Eliminate the cause of a short circuit.
Excessive current consumption due to an overload in
the electric mains.
Eliminate the cause of excessive current consumption.
Improper fan starting method.
Use a soft starter or frequency converter to start the motor
(see "Asynchronous Electric Motor Starting Methods"
in the "Connection to power mains" section)
.
Improper switching equipment.
Re-select the switching equipment in accordance with the
current regulations and equipment specifications.
The installed switching equipment is of poor quality
or its actual performance falls short of the rated values
stated by the manufacturer.
Re-select the switching equipment by choosing a unit
which successfully passed commutation and load tests
and has a technical compliance certificate. The selection
should be limited to the top five foreign switching
equipment manufacturers.
The fan fails to reach the
required rotation speed due to
serious overheating of the fan
motor.
Fan motor overloaded.
Eliminate the overload.
Improper fan starting method.
Use a soft starter or frequency converter to start the motor
(see “Asynchronous Electric Motor Starting Methods”
in the “Connection to power mains” section)
.
The fan motor runs at
overload capacity with current
consumption in excess of the
rated value.
The fan supplies more air than expected upon motor
capacity selection.
Measure network resistance. Throttle down the network
(add aerodynamic resistance to the air duct network).
Wrong motor phasing. The impeller rotates in the
opposite direction of the arrow on the fan casing.
If necessary, change the impeller rotation direction by
changing the phase sequence on the electric motor
terminals.
Air ducts clogged.
Clean the air duct or the impeller.
The fan supplies more air than
expected.
The resistance values used during the ventilation
network calculations are too conservative.
Check the air ducts for proper shape and cross section as
well as for any dampers present.
The cross section of air ducts increased and their
number reduced during the installation.
Throttle down the network (add aerodynamic resistance
to the air duct network).
Wrong choice of the fan.
Replace the fan with a unit of proper standard size.
TROUBLESHOOTING
