Traction Motors

Gibela underwent a significant transformation when the company initiated a process to consolidate the manufacture of traction motors at the Dunnottar site, effective from April 1, 2019. This move marked a pivotal milestone in the company's evolution as a rolling stock manufacturer, bolstering its manufacturing capabilities and expanding its footprint. The decision to retain in-house manufacturing of the traction motor was driven by the aim to minimize industrial risks, ensuring a seamless 100% process carry-over. 

The business unit's primary objective is to produce nearly 8000 traction motors for the PRASA revitalization project, thereby fulfilling contractual obligations for local content. Establishing a local footprint for this crucial component has long been recognized as a strategic imperative for the development of South Africa's rail and related industries.

With a dedicated team of over 80 skilled South African artisans and engineers, the business unit demonstrates the capability to construct a complete traction motor from scratch within a remarkable 7-day timeframe.

The 350 kW asynchronous induction traction motor, plays a critical role in converting electrical power into mechanical energy, which propels the train by driving its axles. This conversion is achieved through the creation of a rotating magnetic field. The rotor, the rotating component, follows with the rotating magnetic field generated by the static windings (stator). Enhancing the power-to-mass ratio stands as a key technical challenge associated with traction motors.

Notably, traction motors serve not only for propulsion but also for deceleration, with up to 75% of maximum braking effort achieved through electrical braking via the motor (equating to 6500 kW per train). Moreover, they can inject regenerative energy back into the line, enhancing energy efficiency for the client by allowing other trains to utilize this surplus energy.

Each train (Isitimela Sabantu) is equipped with 16 traction motors, situated within the bogies of the four middle cars of the Electric Multiple Units (EMU).  These motors are distinguished by their high starting torques, facilitating swift acceleration of passengers from the platform.

The Motors business operates as an independent business unit within Gibela, encompassing dedicated departments for various functions. These include work package management, warehousing, supply chain management, quality assurance, production, and industrialization. However, certain resources are shared with the main rolling stock site, notably in areas such as Environment, Health, and Safety (EHS), finance, communication, and sourcing.

In terms of workforce composition, the department prioritizes diversity and inclusivity. Notably, women constitute a majority in several process areas, such as coil insulation and winding, comprising 55% of the total workshop staff. Moreover, the department has actively recruited 16% of People With Disabilities (PWD) to produce traction motors.

The PRASA motor design, is tailored to accommodate the narrow-gauge specifications of the South African rail infrastructure while maintaining high reliability, as is crucial in the rail industry. Meeting these stringent requirements necessitates local expertise in specialized processes, including welding, torque tightening, vacuum pressure impregnation, painting, and brazing. These processes are classified as "Special Processes" according to the IRIS definition, implying that the conformity of the resulting product cannot be economically validated without destructive analysis prior to use. As a result, operators must possess multidisciplinary skills to ensure "right first time" outcomes.

Additionally, a highly skilled quality department oversees the meticulous inspection of 98 hold points throughout the entire manufacturing process cycle. Furthermore, a dedicated testing team conducts over 17 routine tests to verify the integrity and performance of the traction motors.

During the COVID-19 period, the Motors business successfully prepared its production facility, assembling, commissioning, and validating all necessary jigs and equipment with remote support from OEM suppliers due to travel restrictions. The team at the Dunnottar site collaborated with the Participating Unit in France (Ornans), deploying skills transfer sessions to a core team focused on producing the initial traction motor. This motor underwent comprehensive type testing in France, leading to Gibela's qualification in December 2021 to produce traction motors under license. Subsequently, production ramped up swiftly, reaching a throughput of 100 traction motors per month within just 11 months.

Looking ahead, the business aims to exceed an annual production target of 1000 traction motors in the coming years.

A strategic decision was made to redesign the stator frame to facilitate its localization. This initiative aimed to simplify fabrication by introducing a fully casted frame, eliminating the need for welding. Gibela also worked on developing local manufacturing suppliers for specific industrial processes, including steel castings, sheet metalwork, lamination stamping, machining, forging, and copper alloy extrusion. As of now, all machining and sheet metalwork have been fully localized.

Despite challenges, production consistently achieved quality defects per unit well below performance indicator targets, maintaining high productivity rates throughout.