Home > Fixed or pluggable: Connecting high currents and voltages quickly and reliably

Fixed or pluggable: Connecting high currents and voltages quickly and reliably

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New PCB and feed-through terminal blocks from Phoenix Contact have been designed for the photovoltaic industry as well as for traditional sectors. These terminal blocks quickly and securely connect heavy currents and voltages through the housing wall and to the PCB.

Renewable energies especially photovoltaics (PV) and wind energy continue to play a key role in efficient power generation. Compared to more traditional sectors, photovoltaics and wind energy plants typically have tougher quality requirements. 

Photovoltaic and wind power plants and their peripheral devices must withstand temperature fluctuations and vibrations and ensure that currents and voltages are transmitted stably over long periods of time. This also applies to the power connectors of the devices, which serve as interfaces for the connection of devices, and are indispensable for electrical operation.

First feed-through terminal block with quick connection technology

Whereas the requirements specified in the standards are the same across these industries, device design differs greatly, especially with respect to power connectors. For example, in power inverters, the main electronics are separated from the connection area for the feeder cable by separate chambers and are therefore not accessible. To connect both chambers, a high-current feed-through terminal is required, and has to be reliable and also perform stably – not just in the photovoltaic system. 

The PLW 16 feed-through terminal block from Phoenix Contact is the first non-pluggable feed-through terminal block on the market to meet these requirements, thanks to its quick connection technology. 

Rigid conductors with cross sections up to 16mm² can be externally connected using push-lock lever technology. Inside the device, conductors up to 6mm² can be easily connected using push-in direct plug technology. Wires with prefabricated ferrules can be inserted into the cable funnel with little physical effort. In factory production environments, this is a great advantage during the assembly process. Internal wiring using cables allows for more flexible device design, since the PCB can be positioned in the device with greater tolerances and the cables compensate for a certain amount of play.

One way of attaching the PLW 16 feed-through terminal block to the device is to use a terminal wedge, whereby the conductor is manually inserted into the latching slot of the terminal. Another method is to have the terminal attached from the outside using M3 screws.

Reliable sealing for AC power delivery in the field

Preventing unauthorised access to the power delivered to the grid is becoming increasingly important in the photovoltaics industry. In some countries, standards already require the terminal to be sealed, usually on the AC delivery side. The PLW 16 panel feed-through meets this safety requirement as it features a sealing orange strip on the feed-through terminal block as a standard feature. Once the conductor has been connected by pressing down the lever, the strip is inserted into the latching slot over the levers (rotated 180°). The sealing strip is then tightly attached to the terminal by the holes on the left and right using a sealing wire with a maximum thickness of 1.4 mm. To move the lever, the seal would have to be destroyed, providing visual evidence of misuse or tampering. 

If a device must be connected with a protection rating of more than IP20 for a certain application, the PLW 16 feed-through terminal block can reach water-tightness ratings of IP65/IP68 thanks to an optional sleeve housing designed to meet the special requirements of the photovoltaics industry, where UV stability and ammonia resistance are mandatory. The easily accessible screw connection also allows the plug housing to be sealed so that unauthorised access can be detected.

Special products for special applications

Phoenix Contact has introduced other high-current panel feed-throughs in addition to the panel feed-through with a push-lock lever. Connection technology is the most important factor in selecting a conductor connector. As an upgrade to conventional connection technology using screws, the new UW series (Universal screw through wall) was developed based on commonly used standards. With the UW range, cross-sections up to 25mm² can be inserted through the panel into the device even more compactly than before. This is an especially useful option, given the need for compliance with the 600 V UL voltage requirement. 

The RW series (Ring-cable-lug through wall), which features rugged bolt connectors is more useful for applications with large cross-sections up to 105mm², and has a market-leading current-carrying capacity of 309 A.

Also new to the market, the PW series (Push-in through wall) has been enhanced with a large panel feed-through terminal block (called PWO 16). The terminal provides a wiring solution that saves installers a lot of time, thanks to its push-in quick connection technology. A 45° cable exit saves space during wiring and makes the terminal location more easily accessible, as the cable can enter and exit in one direction.

The feed-through terminal consists of an inner and an outer part, and is fastened to the device simply by snapping the two parts together without the need for a tool. Fine latching grooves on both parts ensure that the terminal is firmly seated in the device, regardless of panel thickness. The terminal can also be attached to the housing in other ways including using screw fastener flanges from the exterior, using commercially available rivets from the inside, and with self-cutting Phillips screws also from the inside.

Since devices are potted on the inside in numerous applications, the panel feed-through PWO 16 also comes in a potted version, making the terminal especially well-suited for manufacturers of filters, transformers, inductors, and batteries. 

Pluggable through the wall

The number of components placed on a PCB is always increasing, which requires the PCB to be supported. In this case, panel feed-throughs permanently attached to the device housing are recommended as they relieve the strain on the PCB. In addition, peripheral devices installed in the control cabinet are confined to a predefined space. Since there is not enough room in the device for the wiring, pluggable solutions with a soldered base terminal and an accompanying plug connector are used. This base terminal, and therefore the PCB, can be positioned close to the device panel to save space.

Another advantage is that the accompanying plug connector can be shipped preassembled, allowing it to be connected in a plug-and-play style on site. The pluggable panel feed-throughs of the product range come in three performance categories: 41 A/ 6mm², 76 A/ 16mm² and 125 A/ 35mm².

The two smaller performance categories can be attached to the device panel with a self-cutting screw and matching plastic anchor fitting or using a tool-free snap lock. This customised integration of the panel feed-through, like the installation of the panel feed-through in the device, ensures a dust-free connection and transmission of power to devices.

The wide range of panel feed-throughs available from Phoenix Contact, whether pluggable or firmly installed in the device, means that the right solution is available for any application and performance class.

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