As a high-tech company and leading manufacturer of wind power systems in Germany, ENERCON GmbH supplies technically innovative wind power systems. Through its efficient systems, ENERCON has made a significant contribution towards giving Germany the lead over the traditional wind power country of Denmark (570 MW), moving it into second place behind the USA (836 MW) in terms of global wind power exploitation. The ENERCON systems are tailor-made for specific markets and locations and are used productively in civil wind farms, by agriculture, industry, commerce, power utilities and municipal authorities. Great emphasis is placed on quality in the selection of individual components. This is why the electrical systems employ various products from the specialist in connection technology, PHOENIX CONTACT.

Improvements in Servicing thanks to COMBICON
Plug connectors which can be mounted on printed circuit boards are required in order to allow the electronic components of the control system to be exchanged rapidly in case of servicing. These connectors make it possible to exchange the p.c.b. without the need for tools. A plug connector with a large connection range was selected because of the extremely large number of differing cross-section ranges resulting from the use of sensor and feeder lines. The ENERCON technicians decided in favor of the MSTB 2,5 from the COMBICON range with its many variants. The 2.5 mm² screw clamp connection (internal cylindrical gage A3) permits all of the conductor cross-sections encountered there to be reliably connected. This dimension applies to solid and stranded conductors, so the cage principle means the composition of the conductor is only an incidental factor. The external proximity switches are powered with 24 V or 48 V via a controller. The transformation from 230 V to 24 V/48 V also takes place on the printed circuit board. The connections required for this are implemented either using the standard 5 mm pitch connector or with the type GMSTB 2,5 in 7.5 mm pitch. The robust contact system is made from high-strength copper alloys and ensures that the COMBICON plug connectors possess a current carrying capacity of 12 A. Together with the careful surface treatment, this guarantees the best possible levels of contact quality, clamping security and resistance to corrosion. Even currents of only a few mA, as occur in the application described here, are therefore sure to be transmitted.
Fixed terminal blocks clipped onto top hat rails are generally used in the ENERCON switch cabinet for elements which cannot be mounted on a p.c.b., such as emergency off switches, sockets, etc. ENERCON relies on the convenience in application offered by UK 5N universal modular terminal blocks. They are colored to denote L, N and PE and labeled using the ZB6 labeling system, so using this system guarantees that the wiring can be clearly identified. Various conductor cross-sections are used during the installation of this type of switch cabinet, which means using the UK 5N with its connection cross-section between 0.2 mm² and 6 mm² represents a universal solution. The space-saving UK 3N can be utilized instead for smaller cross-sections. It is only 5.2 mm wide and establishes a secure connection, just like the wider UK 5N by means of its cage principle.

Plug Connections Come Wind or Weather
Plug connectors on a wind power system have to withstand harsh ambient conditions such as heat, cold, rain and wind. Heavy industrial connectors are the ideal candidates for this application. They are used directly in the switch cabinet at the foot of the wind power system as well as high up between the generator and the rotor. In smaller systems (500 kW), the height of the hub is 43 m, rising as high as 68 m in a 1.5 MW system. This environment requires protection class IP 65 at least.
The plug connectors used in this type of system transmit sensor signals as well as the associated electrical power supply. Industrial connectors supplied by PHOENIX CONTACT under the product name Heavycon meet the requirements of protection class IP 65 and also have a robust cast aluminum housing. This housing protects the internal contacts (6 to 128 pins) against mechanical effects. The robust locking feature prevents the contact from working loose inadvertently, for example as a result of vibration or mechanical tension. All housings can be equipped with either a plug or a female insert in order to be able to connect the live conductors to the shockproof female insert. The need to route both power and signal conductors from the switch cabinet to the generator means the Pluscon HCM range could be used in future.

Nothing Doing without Sensors
Sensors measure the speed of rotation, wind direction and speed. The rotor blades turn so as to present their minimum profile when there is no wind or in case of strong gusts. This mechanism prevents unprofitable operation of the generator as well as protecting it against damage caused by running at excessive speeds.
The sensor cables are brought together in the gondola in order to avoid having the large number of sensors connected to the ground station via complicated cable harnesses. This concentration can be achieved using sensor/actuator boxes, for example. The Pluscon SAC product family provides an extensive range of sensor/actuator cabling for this purpose.

Summary
Wind power systems have to operate for many years in order to make themselves pay. Such operation can only be achieved by high-quality products. For this reason, ENERCON selected the connection technology from PHOENIX CONTACT.

Dipl.-Ing. Ralf Hausmann