Motor anomaly analysis
Release time:
2023-04-12 00:00
Fault identification must be very familiar with the various properties, structures and various parameters of the diagnostic object. The motor consists of several independent and interrelated working systems: the electrical system, the magnetic circuit system, the insulation system, the mechanical system and the ventilation and cooling system.
Motor components: stator, rotor, bearing units, base plate and some ancillary structures (e.g. fan, commutator, etc.).
A fault in a motor often shows multiple signs of failure. There are also several causes of faults reflecting the same fault sign.
The commutation deteriorates during motor operation due to overload, mechanical vibration, commutator deformation, improper maintenance, low humidity and other causes.
Harsh environments and harsh operating conditions, as well as operation beyond the permissible range specified in the technical conditions, are often the direct cause of motor failures.
Typical motor faults are summarised as follows
1) Stator iron core failure
usually occurring on large turbine generators, mainly as a result of overheating deep in the core;
Early signs are large loop currents, high temperatures and pyrolysis of the insulation material;
2) Winding insulation failures
Causes: insulation ageing, insulation defects and contaminated lead sleeves;
Main symptom: increase in stator winding partial discharge;
3) Stator winding strand faults (generators)
short-circuit between strands producing arc generation, possible development of an earth fault or a phase-to-phase short-circuit fault;
Signs: gases generated by pyrolysis of insulating material in the cooling water of water-cooled motors;
4) Stator end coil faults
Displacement of the stator end winding due to the impact of the operation process, resulting in insulation deterioration and partial discharge.
Signs: vibration and partial discharge
5) Cooling water system failure
Signs: high stator bar or cooling water temperature, thermal decomposition of the insulation material and possible discharge.
6) Rotor winding faults (asynchronous motors)
The main rotor faults are broken rotor guide bars, which cause torque jumps, speed fluctuations, rotor vibrations and overheating.
The most common detection method is stator current monitoring (which is difficult to monitor), often using vibration and insulation material pyrolysis monitoring methods.
7) Rotor winding faults (generators)
Mainly turn-to-turn short-circuit faults. Inter-turn short circuits can be caused by arcing caused by dirt on the surface of the conductors in the slot when the generator is started or stopped at low speed, or by huge centrifugal forces and high temperatures affecting the windings and winding insulation.
Turn-to-turn short-circuit faults can cause local overheating or even lead to grounding of the rotor.
A common monitoring method is the use of air gap magnetic density monitoring, by detecting the air gap magnetic density, the number and location of inter-turn short circuits can be determined; monitor whether bearing vibration is enhanced.
8) Rotor body failure (all types of motors)
caused mainly by large rotor centrifugal forces, large negative sequence transient currents and rotor uncentricity;
Signs: excessive vibrations at the bearings.
Other Dynamics
Steadily Moving Forward: Second Week of Work
In the new year, the market competition remains intense. Motor energy efficiency upgrades, cost control, delivery cycles... every challenge requires close collaboration between upstream and downstream partners. At Chuangxin Kai Motor Co., Ltd., we firmly believe that only by perfecting every component can we achieve the outstanding performance of our customers' motors. In the second week of work, we are already ready. If you are looking for a reliable supplier of motor accessories, if you have a new project that requires prototyping, or if you want to find a partner for long-term and stable cooperation Welcome to contact us, and you are also welcome to visit our factory for an on-site inspection. Take a look at our workshop, take a look at our products, and take a look at our team of dedicated manufacturers.
Contact Information
Address: No. 7 Chuangxin Road, Luoyang Town, Changzhou City