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- Synchronous electric motors
Synchronous electric motors
// Key materials
Where to start
The foundational articles of the category: the complete repair process and stator rewinding.
Overview
Synchronous motors: design, operating principle, types, characteristics, faults and repair
The foundational article of the category — design, excitation systems, duty types and typical defects.
Read the articleTechnology
How electric motors are repaired: the complete process from fault detection to testing
The full works-repair route, with verification steps at every stage.
Read the articleTechnology
How a motor stator is rewound: the full technology from fault detection to testing
Winding calculation, laying, insulation, impregnation and post-rewind testing.
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// All articles in the category
Choose a topic
Each article covers one topic: causes, symptoms, the diagnostic sequence, typical mistakes and answers to common questions.
Overview
7 articlesSynchronous motors: design, operating principle, types, characteristics, faults and repair
The foundational article of the category — design, excitation systems, duty types and typical defects.
Read the articleWhat are stator and rotor windings: design, types and faults
Terminology, winding types, materials, insulation and typical faults of electrical-machine windings.
Read the articleWhat is a motor rotor: design, types, faults and repair
Design, rotor types, balancing and typical faults of an electrical machine’s rotating part.
Read the articleWhat is a motor stator: design, winding, faults and repair
Design, winding types, insulation and typical faults of an electrical machine’s stator.
Read the articleHydrogenerator: design, operating principle, diagnostics and repair
Salient-pole rotor design, the thrust bearing, excitation and cooling systems, and typical hydrogenerator faults.
Read the articleTurbogenerator: design, cooling, diagnostics and repair
Stator and rotor design, hydrogen and water cooling, excitation systems and typical turbogenerator faults.
Read the articleHow are generators repaired?
Diagnostics, rewinding, balancing and testing of synchronous generators.
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Technology
8 articlesWhat does a capital repair of a motor include?
The complete process cycle of a capital repair — from intake to final testing.
Read the articleFiberglass laminate in electric motor manufacturing and repair
Grades, properties, applications and machining of fiberglass-laminate parts.
Read the articleElectric motor winding insulation: types, classes F and H
IEC 60085 thermal classes, thermoplastic vs thermoset insulation, and VPI.
Read the articleHow are stator coils manufactured?
Soft random-wound and hard formed coils: winding data, winding, insulation and testing.
Read the articleHow are synchronous rotors rewound?
The full technology for restoring the field winding of salient-pole and non-salient-pole rotors.
Read the articleWhat is electric motor rotor balancing?
Static and dynamic balancing, the causes of imbalance, and post-repair checks.
Read the articleHow electric motors are repaired: the complete process from fault detection to testing
The full works-repair route, with verification steps at every stage.
Read the articleHow a motor stator is rewound: the full technology from fault detection to testing
Winding calculation, laying, insulation, impregnation and post-rewind testing.
Read the article
Diagnostics
11 articlesHow to check the balancing of a motor rotor?
The complete dynamic-balancing procedure and how to tell imbalance apart from other causes of vibration.
Read the articleWhen does a motor need rewinding?
The main technical grounds for rewinding a winding and the diagnostics that precede the decision.
Read the articleCan a motor be repaired without rewinding?
When repair can be done without replacing the winding, and how that is determined by diagnostics.
Read the articleMotor vibration: what it is and how it is diagnosed
Sources of vibration, measurement parameters, spectral analysis and the signatures of typical defects.
Read the articleWhat is a motor high-voltage test
The purpose, types and procedure of a motor’s HiPot insulation test.
Read the articleWhat tests a motor goes through after repair
The complete list of electrical, mechanical and thermal checks for a motor after repair.
Read the articleHow do I measure shaft run-out on an electric motor?
Radial and axial run-out, choosing a datum, and mapping run-out along the shaft.
Read the articleHow do I measure insulation resistance and find an interturn short circuit?
A megger test and finding an interturn short are two different checks that get confused.
Read the articleHow do I test an electric motor’s bearings?
Temperature, noise, vibration, ultrasound, clearances and post-disassembly inspection.
Read the articleTesting the stator of an electric motor
Insulation resistance, surge test, core loop test, checking the connections.
Read the articleTesting the rotor of an electric motor
Squirrel-cage bars, shaft run-out, imbalance, slip rings.
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Faults
6 articlesWhy do an electric motor’s brushes spark?
Causes of brush-commutator sparking and how to diagnose it.
Read the articleWhy does an electric motor lose power?
Electrical, magnetic, thermal and mechanical causes, and the diagnostic sequence.
Read the articleWhy do motor windings burn out?
Overload, running on two phases, breakdown to the frame, repair mistakes.
Read the articleInterturn short circuit in a motor winding
The most dangerous hidden winding defect and the methods that reveal it.
Read the articleWhy does an electric motor vibrate heavily?
Imbalance, misalignment, bearings, electromagnetic causes.
Read the articleWhy is an electric motor noisy?
Mechanical, electromagnetic and aerodynamic noise — how to tell them apart.
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Overheating
4 articlesWhy does an electric motor get hot?
The main causes of overheating, diagnostic methods and ways to eliminate it.
Read the articleWhy does the stator of an electric motor get hot?
Overheating of the stator winding and magnetic core.
Read the articleWhy does the rotor of an electric motor get hot?
Damaged bars, increased slip, prolonged starting.
Read the articleWhy do electric motor bearings get hot?
Lubrication, misalignment, axial loads, worn components.
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