The most common fan failure is an electrical or mechanical failure of the electric motor. Diagnosing an electric motor fault is a complex discipline and determining the cause of a mechanical or electrical electric motor fault is very difficult without knowledge of the operating conditions of the fan, even for our company's specialist department. Modern electric motors alone have a failure rate of 0.00005 according to manufacturers' data. After installing an electric motor in a fan, our company's statistics record a value of 0.004, with 99% of complaints being caused by electric motor failure, of which only about 0.3% of failures are recognized as complaints by the electric motor manufacturers. Nevertheless, some failures and their causes can be detected quite easily. For simplicity, electric motor failures can be divided as follows.
- Bearing failure
is a mechanical failure that can have a multitude of electrical, mechanical and "air" causes. For an abbreviated analysis, please see the "bearing-life" FAQ on our website. Bearing failures are virtually always failures caused by faulty operation, only a negligible proportion of claims are found to be justified by the bearing manufacturer. - Electric motor winding failure
is an electrical fault originating in winding burn due to current overload, electrical breakdown in the winding, or deteriorated insulation. - Burned windings of an electric motor
- is caused by thermal overload of the winding due to:
- power overload of the motor by an inappropriate fan operating point
- phase failure in three-phase motors
- start-up winding disconnection in capacitor motors
- not using proper current protection in a motor without protection in the winding
- non-application of protection in motors with thermal protection in the winding
- power overload of the motor after bearing failure
- thermal overload of the motor due to frequent starting without heat dissipation after starting, only motors with built-in protection can withstand this overload
- limiting the cooling air supply to the motor
- reduction of the load capacity of the electric motor due to increased losses in the magnetic circuits during voltage or frequency speed control
The stated causes of motor winding burn in the fan lead to the claim not being accepted.
The winding burn can be caused by:
- operating surges in the mains .
- operation of standard motors together with electronic speed controllers and frequency converters
- operation in humid environments
- operation in condensing humidity
- as a result of thermal overload and reduced insulation (motors operated in short-circuit condition, frequent starting not corresponding to the S1 type of operation or single phase failure in three-phase motors and defective protection.
The stated causes of punctured motor winding insulation result in the overwhelming majority of cases recorded by us in the non-acceptance of the claim.
Insulation deterioration is usually caused by operation in a humid environment or in an area of moisture condensation and the claim is not accepted as justified.
The general assumption
is that the motors used in our fans are supplied exclusively by reputable manufacturers such as ABB, Bauknecht, Siemens, SaP etc, these manufacturers produce motors in batches of millions. All motors are subjected to inter-operational and output parameter checks and running tests, motors undergo further electrical and mechanical tests after installation in the fan and undergo further running tests, including the storage of the measured values in the ISO 9001 quality system.
New fans with defective motors from the factory are a myth, the possibility of such a defective delivery from the factory is practically excluded.
Failure rate of motors
operated according to type with protection in the winding or for standard motors with properly set current relay or thermal protection is zero. It is virtually impossible to destroy motors protected in this way!
A motor circuit breaker is not sufficient protection against low overcurrents (e.g. in the region of 1.1 to 2 times In). Such an inappropriately chosen protective element and its thermal trigger characteristic reliably leads to the destruction of the fans, because the thermal protection does not switch off the motor!! Particularly in HVAC applications, changes in the operating parameters of the piping network can cause overload of the motors in radial fans with forward blades. Therefore, always use either built-in protections or properly sized current relays for standard motors, otherwise thermal overload leading to motor destruction will occur.
Claims handling
is always in accordance with our company's claims policy. If the documentation, documents and measured values required by us are not provided in the event of an electric motor and fan failure, the claim cannot be accepted as legitimate.
Special Customer Complaint Service
enables us, at our sole discretion (by the Head of Sales on the recommendation of the Regional Sales Representative), to provide some customers with the parts needed for repair free of charge even in cases where there is no valid complaint.