Gefran S.p.A: "Bello il Sole"
New DC Switchgear for Photovoltaic Applications
Gefran S.p.A., headquartered in Provaglio d’Iseo (BS), Italy, develops components and implements automation solutions for monitoring and controlling both industrial processes and machines. The range covers sensors, drive solutions (such as inverters, servo drives, and converters), semiconductor relays, meters and programmable controllers, right through to software solutions and complete systems. Power inverters for solar installations are the latest product line. Gefran has 800 employees and seven production sites with operations worldwide.
The Gefran started a few years ago with the development of photovoltaic power inverters based on devices for drives. A complete range consisting of nine types from 2 kW to 250 kW for industrial and residential applications has been on offer since March 2010. The power inverters operate both with and without transformers.
The company also offers a generator string box for eight strings. It can be expanded in combinations with 16 or 24 strings and with a switch-disconnector box. In the basic version, the inputs are brought together via string diodes and fuses. The more convenient version also features a current measuring function. The read data is fed to a central data acquisition and evaluation unit via an RS485 interface and Modbus protocol. This enables faulty modules to be detected early and yield losses to be prevented. The range is rounded off with a varistor overvoltage protection.
Eaton’s P-SOL60 DC switch-disconnector is integrated both in the APV 20K power inverter as well as in the JBX string boxes. It is used in the power inverter to isolate the DC input from the solar generator. One highlight is the fact that it causes the isolation of the power inverter using the attached shunt release and a DILM95 contactor on the AC side.
The majority of the P-SOL60s are used in the string boxes as DC switch-disconnectors in order to isolate the string group from the power inverter. Also here the combination with the undervoltage release is used in two versions, in order to open the switch-disconnector in the event of malfunctions on the module side, which the electronics reliably detects.
Gefran also uses other high quality switchgear from the Eaton range: N-S1-DC DC switch-disconnectors, DIL contactors, RMQ pilot devices, Xpole components and NZM circuit-breakers.
P-SOL DC switch-disconnectors
Eaton offers P-SOL DC switch-disconnectors for the rated current ranges 20 A, 30 A and 60 A. The DC isolators are available with IP20 protection for direct mounting in the power inverter or with IP65 protection for external mounting close to the power inverter. The high switching capacity allows the switch to be actuated during operation – even under load. With extensive PV installations the integration of shunt and undervoltage releases allows an optional remote tripping of the (lockable) switch-disconnectors.
The solar installation, like the power inverter, is connected to the enclosed switch-disconnectors via the special solar plug connectors. Depending on the rating, two, four or eight solar strings can be connected on the incoming side via MC3 or MC4 plug connectors. Alternatively types are available for direct terminal connection and cable routing via M12, M16 or M20 cable glands. Eaton offers pre-assembled solutions for different installations, thus making the use of Y cables unnecessary. The rugged housing material also allows mounting in protected outdoor areas. Integrated pressure compensation elements prevent condensation. All enclosed switch-disconnectors are TÜV-certified.
Marcello Baberini, head of Power Electronics Development at Gefran, summed up as follows: “The excellent quality of Eaton products, also with this project, was impressive. The ability of the DC switch-disconnectors to be actuated remotely if required is a particular benefit for our innovative solutions. As early as the development phase of the inverter we were working closely with the specialists at Eaton. However, we are now also pursuing new directions in the area of logistics. For example, we are purchasing the Eaton products required for an inverter as complete kits. Each kit, with only one order number, thus contains all the associated components. This saves us ordering several individual items separately and guarantees us the availability of all the Eaton components required for an inverter.”