Connectors Simplifying Switch Cabinet Construction

New industrial connectors enable the rear mounting of interfaces for switch cabinets. Using this option, all relevant connection steps can be carried out from the inside of a cabinet. Moreover, many installation processes can be shifted to the pre-assembly stage, thus helping to save expensive technician hours in the field. The termination technique can also accelerate processing. For example, the radial cage clamp used by Han ES Press enables a tool-free connection, in addition to offering options for bridging contacts directly on the insert.

 

 

A couple of innovations with connectors help to shorten the production as well as the installation time of switch cabinets in the wind energy sector. As wind turbine manufacturing is a global process, the new techniques enable savings along the entire value chain. Production plants for components such as nacelles, blades and towers are under operation in many countries around the world. These locations must be supplied with a wide variety of components. As parts are produced worldwide and often come from different manufacturers, the wind industry pursues a second supplier strategy.

 

In many international markets, manufacturers are required to meet local content requirements, meaning they rely on local subcontractors. For example, a control cabinet for a wind energy converter (WEC) can come from China, but the nacelle is finally assembled in North America. The manufacture of a wind turbine is therefore based on a complex value chain with reliability, availability and process safety being the key factors.

 

Potential for Cost Savings in WEC Construction
In addition to the global orientation, the search for savings opportunities is a central topic in the wind industry. All parts of the value chain must be examined if wind turbines are to be offered competitively in different markets. As a rule, the focus is put on cutting electricity production costs, which is achieved by reducing capital expenditure (capex) and operational expenditure (opex).

 

However successful the strategies may be, the required reductions cannot be achieved exclusively by enforcing lower purchase prices for materials and components. Instead, new ideas and processes have to be found and implemented along the entire value chain. The component suppliers must be more intensively involved in the manufacturing processes of the wind industry. Especially promising is cooperation in the field of switch cabinet construction.

 

A switch cabinet is a vital WEC component including the control system of the plant as well as contactors, relays and surge protection systems. The manufacturers pre-assemble WEC control cabinets at a few central locations and deliver them worldwide to the nacelle production facilities.

 

Each production of switch cabinets has its own network of suppliers and assembly companies, as only highly specialised and audited firms are allowed to supply finished cable harnesses for the cabinet’s interior. At the end of the process, the switch cabinet manufacturer assembles all parts of the WEC component. Often the outer walls of the cabinets are equipped with connectors using suitable Plug-and-Play mechanisms to simplify the entire integration of the cabinet into the nacelle or the base of the tower.

 

Pre-Assembly Reduces Expenses for Experts in the Field
The rear-fit housings support the installation of switch cabinets. Contact inserts of connectors can be mounted entirely from inside the control cabinet into a bulkhead housing at the surface. This option is called rear mounting and it is available for both metal Han B and plastic Han B enclosures, which are plug compatible. The inserts are freely selectable, so either standard connectors or monoblocks as well as modular connectors can be used for the transmission of different types of media like power, data and signal, and for use with different termination techniques.

 

Connectors with inserts that can be rear mounted open up a significant optimisation potential for switch cabinet manufacturing, installation and operation. They save termination time, reduce errors (by offering coding options) and lead to cost savings, for example when it comes to second or third installation processes or part removals.

 

Due to the rear-mounting option, contact inserts can be pre-attached during the cable assembly. All relevant works can be carried out at an optimised industrial workplace, ensuring as much efficiency as possible; for example, cable harnesses can be mounted into the cabinets at the production site, while the inserts can be snapped into the bulkhead mounted housings from the inside by simple Plug and Play at construction or operation sites.

 

Nacelles not Optimised for Control Cabinet Construction
When using standard hoods and housings, contact inserts cannot be mounted on the cable harnesses until the switch cabinet is assembled completely. Then, conductors must pass through the cut-out in the cabinet wall before the insert can be assembled and mounted from the outside. For electrical connections in nacelle production, the manufacturer needs specialists who can carry out this assembly work, as it is time-consuming to carry it out at the switch cabinet.

 

Workstations in WECs are not optimised for cable assembly. For example, the connectors sometimes need to be mounted in areas that are difficult to access. With the rear-mounting option, this step can be moved to an earlier point in time in the manufacturing and installation process of the switch cabinet.

 

Now, manufacturing halls and production facilities can be optimised in a way that enables the most efficient interface assembly. With the increasing complexity of wind turbines, the effects of savings have become more significant. The higher the number of connectors and complex individual wires, the more savings can be achieved, especially if the manufacturer assembles at specially equipped workstations.

 

Quality Monitoring Becoming More Efficient
The option of rear mounting may also serve as a means of improving quality control. Manufacturers can check the quality of cable harnesses by introducing pre-installed connectors and contact inserts in their assembly lines. Faults can be detected more rapidly and within shorter periods, and the prefabricator can deliver fully tested cable harnesses to the switch cabinet manufacturer.

 

If the configuration of the connector is suitable, time savings of almost 30% can be realised through rear mounting. Combined with further advantages like improved quality control and easier error correction, this connector variant supports manufacturers in their efforts to reduce costs. The savings potential can still be increased if the rear-fit option is accompanied by the right termination technique for contacts and wires.

 

Rapid Termination with Preloaded Cage Clamp
The rapid and toolless termination technique of Han ES Press increases the advantages of the rear-fit option. Compared with standard termination technologies, the time required to assemble a connector can be reduced by half. Han ES Press is a family of inserts that is based on the proven cage clamp technique. You only have to strip the wires and put them directly into the Han ES Press insert. Then you push in the blue actuator, and the preloaded cage clamp tightly encloses the wire, thus ensuring a reliable and vibration-proof connection. There is no need for crimping additional contacts and no special tools are required.

 

Easily Bridging Contacts in Inserts
In a control cabinet, you can find many terminal blocks that multiply or collect electrical wires with the same voltage level in electrical nodes; the number of cables is high and space for terminal blocks is limited. Now, with Han ES Press, the electrical nodes or the potential multiplication can be set up directly at the insert. The wires are easily bridged by inserting the jumpers into the insulation body.

 

The use of various longitudinal and transverse bridges reduces space requirements and saves installation time. In addition to potential multiplication, they allow the construction of star and delta circuits, for example, for connecting sensors. Manufacturers of switch cabinets will benefit from faster termination processes in series production and from quicker wirings, while retaining the full functionality in field installation, no matter whether stranded wires are used or wire ends – with or without ferrules. The named benefits are valid for all terminal boxes used in wind turbines.

 

If both solutions are combined – the rear-fit hood or housing and the Han ES Press insert – they enable the cabinet manufacturer to save time, as they shorten the assembly process, and help save space (especially due to the bridging functionality). These advantages are complementary to all the other advantages of using connectors in the wind industry. In general, they support the realisation of cost savings along the entire value chain of wind energy.

 

Biography
Carsten Edler has worked in the wind industry for more than ten years. In his role as Global Industry Segment Manager, he has experience of working closely with companies around the world. Whilst working with a solution provider, he also met customers along the complete value chain, from OEM level to different sub-suppliers.