Whether rewinding is necessary is not determined solely by the visible damage. We consider the condition of the winding insulation, the type and extent of any electrical or thermal damage, the condition of the laminated core, and future operating conditions. If damaged areas can be reliably contained, a partial repair may suffice. However, in cases of extensively aged or damaged insulation, rewinding is often the more robust solution.

We combine several testing and measurement methods into a comprehensive assessment. This can include insulation and resistance measurements, dissipation factor measurements, partial discharge measurements, as well as thermographic or endoscopic examinations. The decisive factor is not a single measurement, but the interplay of measurement data, trend, design, operating history, and visible condition. From this, we determine whether continued operation, targeted repair, or rewinding is advisable.

The scope of testing depends on the motor, the type of damage, and the agreed-upon acceptance criteria. We check the relevant electrical and mechanical parameters and, depending on the machine, perform functional, idle, load, or acceptance tests. These tests include checking current draw, temperature behavior, vibrations, and stable operation. The results are compared with the defined target or acceptance criteria and documented in a traceable manner.

In inverter operation, steep voltage pulses, harmonics, bearing currents, and reduced self-cooling at low speeds can place additional stress on the motor. Therefore, we consider winding insulation, bearings, cooling, cables, filters, and inverter parameterization as an integrated drive system. From this, we determine whether an inverter-compatible winding or other protective measures are required.

For an initial assessment, we need the nameplate data, design, power, voltage, speed, operating mode, and as precise a description of the problem as possible. Measurement data, photos, fault logs, load information, and the repair history help to narrow down possible causes and determine the next step in the investigation. We also clarify the installation situation, accessibility, and the available downtime window.

Continuous operation, frequent starts, overloads, dust, humidity, aggressive media, or high ambient temperatures can place varying stresses on windings, bearings, and cooling systems. We incorporate these conditions into our material selection, insulation, sealing, cooling concept, and testing program. This ensures that the machine is not only repaired but also evaluated for its actual operating conditions.