Industrial Motor Rewinding, Electrical Engineering & Rotating Machinery FAQs

DELBA Electrical specialises in the repair, rewinding, maintenance and refurbishment of electrical rotating machinery. Its published service offering includes AC and DC motors, generators, wheel motors, alternators and related rotating equipment.

The company's capabilities also include diagnostics, testing, field services, conductor extrusion, conductor covering and coil manufacturing. These complementary capabilities support the repair process from technical assessment through to refurbishment and testing.

DELBA Electrical was established in 1963 by Isidoro Del Piccolo and Armando Balocco. The company has developed from a motor repair workshop into a specialist industrial engineering business serving customers across multiple sectors.

Its history of more than six decades provides a substantial foundation of experience in electrical rotating machinery repair and maintenance.

DELBA Electrical is headquartered in Springs, Gauteng, South Africa, and has also published information about its facility in Alrode, Alberton.

Customers should contact DELBA directly to confirm the most suitable facility, service team and logistics arrangements for their equipment.

DELBA's stated vision includes providing rotating machinery repair and maintenance solutions nationally and internationally. Its industrial capabilities are relevant to businesses operating across South Africa and the wider African market.

Specific country coverage, transport arrangements, site access requirements and project availability should be confirmed directly with DELBA.

Electrical rotating machinery is used across industries that depend on continuous mechanical and electrical operation. Relevant sectors include mining, power generation, manufacturing, steel, petrochemical operations, water infrastructure and other industrial environments.

The suitability of a particular service depends on the equipment, operating conditions, technical requirements and scope of work.

Rotating machinery can involve complex electrical, mechanical, insulation, bearing, balancing and alignment requirements. A specialist repair provider can assess these interacting systems rather than treating the failure as an isolated component problem.

The right repair partner should be able to explain the failure findings, proposed repair scope, testing requirements and factors that affect equipment reliability after the repair.

DELBA's dedicated divisions and supporting manufacturing capabilities provide a broad foundation for addressing different categories of rotating electrical machinery.

Electric motor rewinding is a specialist repair process in which damaged or deteriorated electrical windings are removed and replaced or reconstructed.

The work may involve inspecting the motor, documenting the existing winding arrangement, assessing the stator or rotor, preparing the core, manufacturing replacement coils, installing insulation, connecting the winding, impregnating or treating the insulation system as required, and performing appropriate tests.

The exact process depends on the motor design, voltage, winding configuration, condition and repair requirements.

A motor may require rewinding when winding insulation has deteriorated, an electrical fault has damaged the windings, or testing indicates that the winding system can no longer operate reliably.

However, not every motor failure requires a rewind. Bearing damage, misalignment, cooling problems, supply irregularities or mechanical damage may require different repairs.

A proper assessment should identify the root cause before a repair decision is made.

The decision depends on several factors, including:

• The motor's age, size and overall condition.
• The extent of electrical and mechanical damage.
• The cost and availability of a replacement.
• The efficiency of the existing motor compared with modern alternatives.
• The expected remaining service life.
• The operational consequences of downtime.
• The required repair and replacement lead times.

For some motors, a properly executed rewind is a practical way to restore service. For others, replacement may offer better long-term value.

An engineering assessment should consider the complete lifecycle cost rather than comparing repair and purchase prices alone.

DELBA publishes capabilities covering low-voltage motors, medium- and high-voltage AC motors, DC motors, wheel motors and alternators, along with other rotating machinery categories.

Its large-machines division publishes capabilities for high-voltage AC motor repairs up to 50 MW at 11 kV and DC motor repairs up to 30 MW at 1,500 V.

Actual acceptance depends on the motor's design, condition, dimensions, weight, technical requirements and current workshop capability.

AC motors operate using alternating current and commonly include induction and synchronous motor designs. Their winding arrangements and failure modes depend on the particular design.

DC motors operate using direct current and may incorporate armature windings, field windings, commutators and brushes, depending on the motor type.

Although both may require winding repairs, their construction, diagnostic procedures, repair techniques and testing requirements differ. Repairs should be performed by technicians familiar with the specific machine design.

Low-voltage and high-voltage motors differ in their electrical insulation requirements, winding construction, testing needs and typical applications.

High-voltage machines generally require particular attention to insulation integrity, winding geometry, electrical stress, discharge-related deterioration and the suitability of the insulation system for operating conditions.

DELBA publishes dedicated capabilities for low-voltage, medium-voltage and high-voltage rotating machinery. The appropriate repair approach depends on the machine's design and specification.

Yes. Depending on the fault, a motor may require bearing replacement, shaft repairs, rotor refurbishment, balancing, alignment, cooling-system repairs, cleaning or other mechanical and electrical work.

If the winding system remains serviceable, a full rewind may not be necessary.

The best approach is to establish the root cause of failure and determine which components require repair or replacement.

Common causes include insulation ageing, excessive temperature, electrical supply abnormalities, contamination, moisture, vibration, mechanical damage and unsuitable operating conditions.

A winding failure may also be a symptom of a wider problem, such as blocked ventilation, repeated overloading, bearing failure or a faulty driven machine.

Identifying the original cause is important because replacing the winding without addressing the underlying problem can increase the risk of repeat failure.

A structured reliability programme should consider operating loads, temperature, vibration, bearing condition, alignment, electrical supply quality, cooling, contamination and maintenance history.

Condition monitoring and trend analysis can help identify changes before they result in major failures.

When a motor fails, recording the symptoms, operating conditions and previous repair history can also help the repair specialist investigate the underlying cause.

DELBA's published power generation services include generator repairs, overhauls, stator and rotor rewinding, exciter repairs and selected design modifications.

The work required depends on the generator design, the nature of the fault, operating history and the results of the inspection.

Yes. Stator and rotor rewinding are established specialist repair processes for certain generator faults.

A stator rewind involves replacing or reconstructing the relevant stationary winding system. A rotor rewind involves work on the rotating winding system where the machine's design and fault require it.

These repairs can involve extensive engineering, specialist tooling, insulation work, controlled manufacturing processes and detailed electrical and mechanical testing.

The stator is the stationary part of the machine, while the rotor is the rotating assembly.

Depending on the generator design, the stator and rotor perform different electromagnetic functions and use different winding arrangements.

Both components must work within the machine's mechanical, thermal and electrical design limits for reliable operation.

Warning signs may include unusual vibration, abnormal temperatures, insulation deterioration, electrical test results outside acceptable limits, unusual noise, visible damage or changes in operating performance.

Protection trips or unexplained changes in generator behaviour should be investigated by qualified personnel.

Where there is a suspected electrical or mechanical defect, the machine should be assessed according to the manufacturer's requirements and the site's safety procedures.

A correctly scoped repair can restore the condition of damaged components and address identified failure mechanisms.

Depending on the machine and the findings, repairs may include winding refurbishment, insulation-system improvements, cooling-related modifications or other engineering work.

Any expected improvement in reliability or service life depends on the condition of the equipment, the quality of the repair, operating conditions and maintenance after the work is completed.

A major overhaul may involve inspection and assessment of the stator, rotor, excitation system, insulation, mechanical components and other machine systems.

The work scope is determined by the generator design, the reason for the overhaul and the findings of the inspection.

Depending on the requirements, work may include component repairs, winding refurbishment or replacement, modifications, reassembly and a defined programme of electrical and mechanical testing.

Vacuum Pressure Impregnation is a process used to impregnate suitable electrical windings with insulating resin.

The process uses vacuum and pressure to help the resin penetrate the winding insulation system. The resin is subsequently cured according to the material and process requirements.

When correctly applied, VPI can improve the integrity of the insulation system and help protect windings against environmental and operational stresses.

Electrical insulation separates conductors from each other and from other parts of the machine. It must withstand the electrical stresses, temperatures, vibration and environmental conditions associated with the equipment's operation.

Insulation deterioration can lead to electrical faults, reduced reliability and potentially serious equipment damage.

The appropriate insulation materials and repair procedures depend on the machine's original design, operating voltage, thermal requirements and service environment.

Curing is an important stage in certain insulation and resin processes. A controlled oven provides the specified temperature conditions needed for the selected materials to cure correctly.

Process control matters because unsuitable curing conditions can compromise the intended properties of the insulation system.

The correct time and temperature profile must be determined by the material specifications and applicable repair procedure.

Electrical windings rely on conductors and coils manufactured to the correct electrical, mechanical and dimensional requirements.

Having conductor covering and coil manufacturing capabilities can support the repair process by improving control over the production of replacement winding components.

DELBA states that it became self-sufficient in the extrusion and manufacture of covered copper conductors and coils in 2007.

The suitability of a replacement conductor or coil must always be determined by the requirements of the specific machine.

Dynamic balancing helps identify and correct mass imbalance in a rotating assembly.

Excessive imbalance can contribute to vibration, mechanical stress, bearing loads and premature wear.

The appropriate balancing procedure and acceptance limits depend on the rotor design, operating speed, application and relevant engineering requirements.

Balancing addresses the distribution of mass in a rotating component. Laser alignment measures and helps correct the relative alignment of connected rotating shafts or equipment.

These are different procedures that address different potential causes of vibration and mechanical stress.

A machine may require balancing, alignment or both, depending on the diagnostic findings.

Diagnostic testing helps establish the condition of the machine and provides evidence to guide the repair scope.

Depending on the machine and the fault, the process may include visual inspection, winding resistance measurements, insulation resistance testing, specialised insulation diagnostics, mechanical inspection and other suitable tests.

The appropriate tests should be selected by qualified personnel and interpreted against the machine's specifications, condition and applicable acceptance criteria.

Insulation resistance testing measures the resistance of an insulation system under a specified test condition.

It can help identify certain insulation problems, contamination or moisture-related concerns, but the result must be interpreted in context.

Test voltage, temperature, equipment design, previous readings and other relevant factors can affect interpretation. A single reading does not establish the complete condition of a machine.

Vibration analysis measures and interprets vibration behaviour to help assess the mechanical condition of rotating equipment.

Depending on the equipment and the data available, vibration patterns may help identify imbalance, misalignment, bearing-related problems, looseness or other developing faults.

Trend monitoring can be especially useful because changes over time may reveal deterioration before a major failure occurs.

Vibration data should be interpreted alongside operating conditions and other diagnostic findings.

Laser shaft alignment uses measurement equipment to determine the relative position of connected rotating shafts and guide corrective adjustments.

Correct alignment can help reduce unwanted loads on couplings, bearings and shafts.

Alignment tolerances depend on the machinery, coupling, operating conditions and manufacturer requirements. Alignment should be checked at the appropriate stages of installation, maintenance or repair.

DELBA publishes field services covering inspections, diagnostics, maintenance and on-site repair support.

The suitability of an on-site intervention depends on the equipment, location, safety requirements, available facilities, repair scope and resources required.

Customers should provide the equipment details, site location, fault description and urgency when requesting support.

DELBA has published information about emergency and on-site repair support. Availability for a particular incident must be confirmed directly.

When requesting urgent assistance, provide the machine type, rating, site location, fault symptoms, operational impact and any safety or access restrictions.

This information helps the service team assess the requirements and determine the appropriate next steps.

Post-repair testing should be selected according to the machine design, repair scope, applicable standards and customer requirements.

Depending on the machine, this may include winding resistance checks, insulation-related tests, electrical integrity checks, mechanical inspections, balancing and suitable operational or load testing.

Not every test is appropriate for every machine. The final test programme should be agreed as part of the repair scope and documented in the completion records.

There is no single inspection interval suitable for every motor.

The appropriate frequency depends on the machine's criticality, operating hours, load, environment, manufacturer recommendations, historical failures and available condition-monitoring information.

Critical machinery in harsh or demanding operating conditions may require more frequent monitoring than equipment operating in stable conditions.

A risk-based maintenance programme is generally more useful than applying the same interval to every motor.

Predictive maintenance uses condition information to help identify developing equipment problems and estimate when intervention may be needed.

Depending on the application, it can include vibration analysis, temperature monitoring, electrical testing, oil analysis and other suitable techniques.

The purpose is to make maintenance decisions using evidence about equipment condition rather than relying solely on fixed intervals or waiting for failure.

Preventive maintenance involves planned activities performed at defined intervals or after specified operating periods.

Predictive maintenance uses equipment-condition information to guide intervention.

Both approaches can be useful. The appropriate maintenance strategy depends on equipment criticality, failure modes, monitoring capabilities, operating conditions and the consequences of failure.

Reducing downtime requires more than fast repairs. It involves identifying critical assets, maintaining accurate equipment records, monitoring developing faults, planning spares, improving maintenance practices and investigating repeat failures.

A specialist repair partner can support this process through condition assessment, diagnostics, repair planning and technical recommendations.

The most effective approach combines reliable repair work with measures that reduce the likelihood of the same fault occurring again.

A rewind should restore the winding system in a way that respects the motor's original design and intended operating characteristics.

Poor workmanship, unsuitable materials or changes to the winding design can affect motor performance and efficiency.

However, a rewind does not automatically make an older motor more efficient. Efficiency depends on the complete machine design, its condition, repair method, loading and operating environment.

Where energy consumption is a concern, the repair decision should consider the motor's measured or documented performance and the potential benefits of a modern replacement.

Useful repair records may include the equipment identification, nameplate data, fault description, inspection findings, agreed work scope, components replaced, test results and any relevant recommendations.

Good records make future maintenance decisions easier and help identify repeat faults or developing trends.

For critical equipment, repair history should form part of the site's broader asset management and reliability programme.

Where available, customers should provide:

• Manufacturer, model and equipment identification.
• Nameplate photograph and rated specifications.
• Motor or generator type and application.
• Voltage, power rating, speed and other relevant nameplate information.
• Description of the fault and when it occurred.
• Previous repair or maintenance history.
• Photographs of visible damage.
• Site location and any operational urgency.
• Relevant drawings, test results or technical documentation.

Not every detail will be available for every enquiry. Providing accurate information at the outset can nevertheless help the technical team assess the equipment and identify the next steps.

Use the interactive enquiry checklist below ↓

Turnaround time depends on the motor's size, design, damage, parts availability, winding requirements, testing programme and current workshop capacity.

A relatively straightforward repair may require a different schedule from a major high-voltage motor or generator overhaul.

The most reliable way to establish a realistic turnaround is to obtain an assessment and a repair programme based on the actual equipment and scope of work.

There is no universal price for motor rewinding.

Cost can depend on motor rating, voltage, winding design, damage severity, material requirements, mechanical refurbishment, balancing, testing, transport and the required turnaround.

A proper quotation should define the proposed work and identify any additional repairs that may be required after inspection.

Comparing quotations solely on price can be misleading if the repair scope, testing requirements and quality controls differ.

The assessment process and any associated costs should be confirmed with DELBA when the enquiry is submitted.

Customers should ask what inspection is required, what information will be provided, whether a quotation follows the assessment and how additional damage discovered during dismantling will be handled.

A clearly defined assessment and approval process helps ensure that repair decisions are based on technical findings.

Industrial buyers should evaluate:

• Experience with the specific machine type and rating.
• Suitable facilities, lifting capacity and specialist equipment.
• Qualified personnel and relevant technical expertise.
• Documented repair procedures and quality controls.
• Appropriate testing capabilities.
• Traceability of materials and repair records.
• Clear communication and quotation processes.
• Relevant certifications and their current validity.
• References or evidence of comparable completed projects.
• Ability to support the equipment's operating and maintenance requirements.

The best provider is one whose demonstrated capabilities and proposed repair process match the technical demands of the equipment.

Before approving a repair, procurement teams should understand the proposed scope, expected turnaround, testing requirements, warranty terms, exclusions and approval process for additional work.

It is also useful to clarify whether the quotation includes transport, dismantling, reassembly, balancing, coating, commissioning support or other associated services.

A well-defined scope makes quotations easier to compare and reduces misunderstandings during the repair process.

A useful starting point is to identify the equipment, describe the operational problem and share the available technical information.

For critical machinery, customers should also explain the consequences of downtime, any relevant maintenance history, site constraints and required operational deadlines.

DELBA can then be approached to discuss the equipment, applicable service capabilities and the next steps for technical assessment.

Large rotating machinery requires more than a workshop with sufficient floor space.

Depending on the machine, the facility may need appropriate lifting capacity, handling arrangements, specialist winding equipment, insulation processing, balancing facilities, electrical test equipment and suitably trained personnel.

The facility's capabilities must match the equipment's dimensions, mass, voltage, power rating and technical requirements.

DELBA publishes a dedicated large-machines division and specialist power-generation repair capabilities. Specific equipment acceptance should be confirmed against the current technical scope.

Where a supplier has suitable capabilities across several equipment categories, a customer may be able to coordinate multiple repair and maintenance requirements through one technical relationship.

The practical benefit depends on the provider's actual services, facility capacity, geographic reach and experience with the equipment concerned.

DELBA's published service portfolio spans multiple rotating machinery categories and supporting manufacturing and field services.

Critical machinery can affect production, safety, power availability and the performance of connected systems.

A repair decision should therefore consider the complete machine, the original fault, operating conditions, engineering requirements and the tests needed to verify the completed work.

Technical expertise helps ensure that the repair scope is appropriate, that relevant failure mechanisms are investigated and that the customer receives meaningful information about the machine's condition.

DELBA publishes specialist capabilities in large AC and DC motor repair, power-generation equipment, generator refurbishment, winding work, testing and related rotating machinery services.

Whether it is suitable for a particular project depends on the equipment specifications, required scope, applicable technical standards, location and current capacity.

Industrial customers should submit the relevant machine information for a capability assessment and quotation.

Visit the official DELBA Electrical website at https://delba.co.za/ and use its contact or enquiry channels to discuss your requirements.

When submitting an enquiry, include the equipment type, nameplate details, fault symptoms, location and any available technical documentation.

Providing this information helps the team understand the request and determine the appropriate next steps.