Retrofitting for maintenance of old switchgear facilities

What can be done if critical components in an old switchgear facility are no longer available? Normally, it would not make financial sense to design a completely new part. EPS GmbH's solution required only a fraction of the costs of a new facility or a new design. For this issue, HARTING has cooperated to adapt a standard industrial connector to the specific requirements of the old technology.

For machines and facilities with operating lives of up to 30 years, maintenance and servicing can present a great challenge. Components have been discontinued and are no longer available. Stocking such components is not economical and often not possible. Many components no longer meet current technical requirements and may contain problematic substances such as asbestos, mercury or PCBs.

Design a new part or retrofit the old switchgear facility?

"In one of our customer's power plants, critical components in a historically old switchgear facility were no longer available. A one-to-one replacement of the old parts with new components was not possible. This endangered the maintenance for the entire plant. "So what could we do?" Benedikt Holtmann, managing director of EPS Energy Protection Services GmbH, describes the initial situation. EPS has been active in the market since 2013 – serving international customers in all aspects of electrical energy and power supply. EPS creates power supply strategies, takes care of the turnkey construction and commissioning, and even maintains the facilities. These include uninterruptible power supplies (UPS), rectifier and inverter systems, power supplies with special requirements, battery systems and construction of their special devices.

At the EPS customer's power plant, it seemed that neither a newly designed solution nor a new facility would be economical. This particular issue concerned a 19-inch rack in a control cabinet. This push-in unit with discontinued electronic, electrical and mechanical components had a special size. The interfaces were mounted floating in a frame and were blindly inserted into the opposite side in a self-aligning manner (blind-mate connector). The push-in rack connectors were therefore the key components for which a solution had to be found.

"Neither the old manufacturer nor the old tools were available and a newly designed part was out of the question. That is why we were searching for a technically feasible and economically justifiable strategy. However, we lacked the special expertise to use plug contacts for such a special solution," says the EPS managing director about the problem.

Harting's field service explained the possible options to us: "The modular industrial connector Han-Modular^® is well suited for such requirements. It can combine different modules, as needed, for transmitting signals, data, energy and compressed air within one connector. With HARTING Customised Solutions, we have a separate division that can make customised adaptations," explains Heinrich Schmettkamp, sales engineer for HARTING field service.

Project planning for a customised connector

Our goal was to adapt the standard Han-Modular^® industrial connector to fit the requirements of the old switchgear facility. With the 19-inch push-in unit, the floating bearing and the blind-mate technology, the design and dimensions were already stipulated within very narrow limits. Performance requirements such as current carrying capacity and mechanical strength of the plug contacts also had to be observed.

The implementation stages included preliminary discussions with the sales department, clarifying the technical requirements with HARTING's project engineering department, initial strategies of the project planning experts, then a CAD construction, and finally a pilot series with prototypes. The prototypes were then tested on site in the old plant for mechanical compatibility. After a few adjustments, the solution was finally ready for series production. Electrical tests and a test for earthquake resistance followed. "These tests ensure that the contacts do not come loose even when there are seismic vibrations. It was also necessary to prove the safety of the insulation between the contact pins under high currents," summarises Benedikt Holtmann concerning the requirements for the quality tests.

The desired variants were then defined for the connector. The 24 control contacts need to have different electrical assignments, colours and labels, while remaining mechanically unchanged. Initially, 100 push-in modules were manufactured for the old switchgear facility. Several hundred units shall be delivered within three years.

The EPS managing director emphasises that this adaptation of an industrial connector has also been commercially successful, although it is only a small series production. This would hardly have been possible in the normal operating procedures of a mass producer. The project development of the connector for the old switchgear facility was implemented by a separate division at HARTING.

HARTING Customised Solutions

HARTING Customised Solutions (HCS) develops customised solutions for the automation, railways, mechanical engineering, robotics and wind energy sectors. Typical projects deal with the project-specific assembly of cables. Users no longer have to worry about the scheduling and quality control for components. Thus, they can save valuable time during the installation and initial commissioning of their facilities. In addition, there is no longer any need for skilled cable-assembly personnel when installing the prepared cables.

HCS also focuses on customer-specific system cabling, including ready-made kits for frequency converters and sensor cabling. HCS is also the contact point for customised newly designed connectors (e.g. for medical technology, for acid and oil-resistant motor cabling or with special housings for power supply and power distribution).

Technically perfect and economically advantageous

The managing director of EPS GmbH considers this project for the old switchgear facility to be very successful for several reasons: "This renovation enabled us to extend the operating lifespan of the old facility by another 20 years. The connectors are replaced in a technically proper way. The quality is high. The installation effort required for the cabling is low and the facility downtime is minimised." Since the retrofit of the facility is partially covered by existing coverage, no further costly approvals by authorities such as the German Technical Inspection Agency (TÜV) are required. No need for additional training (since there are no operating changes for the operating personnel). Furthermore, the safety of the facility is ensured because the old components are replaced and the documentation requirements are low. The managing director also emphasises the excellent cooperation with HARTING: "It was very professional, collegial and enjoyable."

In the end, however, it is the commercial factor which is decisive: "By adapting a standard industrial connector for inserting into the old switchgear facility, we were able to limit the costs to a fraction of what they would be for a newly designed part or a new facility," explains Benedikt Holtmann. For him, it is also important that EPS, as a relatively young company, has successfully implemented such a technically demanding retrofit project – in form, function and within budget.