CONNEX Creates Compact All-Rounders from Power Transformers

The trend towards increasingly compact substations and the dynamic changes to energy infrastructures place new demands on power transformers. They are expected to provide maximum flexibility along with optimum safety and efficiency for a service life of at least 40 years.

Such demands can be met by the dry-insulated and modular Connex connection system, which includes all of the components required – from cable fittings, to plug-in bushings, through to solid-insulated surge arresters.

Originally conceived as a cable connection, Pfisterer eventually refined the space-saving Connex system, turning it into a universal plug-in element and transformer connection device. Today, it represents the largest product line for voltage ranges up to 550 kV by offering a wide variety of cable terminations and connections, surge arresters, plug-in bushings, sliding joints, and voltage testing systems. The connection system makes it possible to replace or exchange all Connex components quickly and at any time to ensure that transformers can be conveniently redeployed.

Flexible for changing networks

The Connex connectors allow power transformers to remain flexible enough to cater to future applications, because various components such as plug-in bushings or solid-insulated surge arresters can be easily connected without requiring the sensitive equipment inside the transformer’s casing to be accessed. The latter is also not required to establish a connection to the power supply or to carry out an on-site check, which in turn reduces the time spent on configuring the initial installation by 75 percent. In addition, the extensive time and money spent carrying out oil or gas-related work for conventional systems is ruled out altogether. Connex therefore facilitates the fast and easy changeover of transformers at any time. Even if the infrastructure networks change in the meantime or further down the road, the investment made in a transformer holds its value throughout the entire service life of the unit when the plug-in Connex system is used.

For compact installation

Transformers equipped with Connex cable connections and surge arresters can be operated economically in the tightest of spaces. Unlike air-insulated arresters and plug-in bushings, solid-insulated Connex components have a very compact design that does not require minimum clearances between phase connections or elaborate busbar configurations for the power supply. This then makes it possible to install and connect substations using a small amount of space – a key advantage, especially in densely populated areas.

Touch-safe maintenance

More and more substations are being installed in buildings and in city centers, such as the new Oerlikon substation in Zurich. However, space-saving constructions in downtown environments come with safety requirements. “Each distribution station is exposed to external, partially unpredictable influences that may affect its operations. Conversely, the systems themselves can pose a risk to the environment. Solid-insulated connection technology can either eliminate both risks or at least minimize them”, explains Ruben Grund, Head of Technology for Cable Accessories at Pfisterer. Take maintenance, for example. The more compact a unit is, the greater the chance that service personnel will inadvertently come into direct contact with live, exposed parts. This risk is completely avoided with fully encapsulated Connex connections, which are touch-proof and can therefore be erected safely, without the need to put up protective barriers.

CONNEX against electro-smog

Switzerland is home to Europe’s most stringent regulations on non-ionizing radiation protection (NIRP). The state requires locations that are frequented for extended periods of time to have a system threshold of a maximum of 1 µT (microtesla) load. This upper limit is met economically by Connex, since the full encapsulation of the system greatly minimizes the electromagnetic fields surrounding connected cables and components.

Plug-in surge arresters

Connex not only reduces the risks for individuals, but also protects high-value capital investments. A lightning strike or a switchgear assembly that suddenly operates at maximum capacity can cause catastrophic damage to a transformer. None of this poses a problem to the plug-in Connex surge arrester, however. Placed directly on the equipment, it provides the best possible system protection because its metal-oxide capsule accurately disperses any incoming overvoltage before it can do damage. Compared to the more commonplace air or gas-insulated arresters, surge arresters from Connex offer several benefits, one of which is that they can be installed in tight spaces because their insulation and field control are made from solid silicone. Environmentally-damaging fluids and SF6 gas are also not used. Consequently, there is zero internal gas pressure, which means that pressure vessel regulations do not apply and a gas-monitoring system does not need to be used. Finally, the integrated plug-type connection design allows Connex surge arresters to be easily replaced without the need to open the transformer.