High-performance DC switching

Jon Lawson

Eaton is ensuring reliable control of frequent DC switching with the introduction of its new DILDC300/600 range of hybrid contactors.

Compact and dependable, the power management company’s new contactors support loads of 300 to 600A at up to 1,000VDC.

Conventional contactors all require maintenance (replacement of contacts) after approximately 10,000 to 25,000 electrical operations.

However, Eaton’s new DILDC contactors require no maintenance and provide an operating lifespan of more than 150,000 electrical operations.

As well as having extremely long lifespans, DILDC contactors can handle 1,000 V DC per pole and current flow in both directions (bi-directional/polarity-insensitive).

The contactors, which can be controlled conventionally or with a programmable logic controller (PLC), have a compact frame size that reduces costly panel space requirements.

In addition, the contactors feature a wide-range coil that covers AC operating voltages from 110 V to 250 V as well as DC operating voltages from 110V to 350V.

Eaton’s new DC hybrid contactors provide a technically efficient and cost-effective solution in a wide range of applications. These include solar energy installations, energy storage systems, battery test benches and DC grids (e.g. on ships, power supplies in rolling stock and the charging infrastructure for electrical vehicles).

To achieve their performance and long lifespan, Eaton DILDC300/600 contactors use novel hybrid switching technology. They have two mechanical contacts – an extinguishing contact and an isolating contact – connected in series.

Furthermore, an IGBT (solid-state switch) is connected in parallel with the extinguishing contact. When the contactor is required to break a circuit, the current commutates to the IGBT with opening of the extinguishing contact.

Next, the IGBT is turned off to interrupt the current and finally, the isolating contact opens to provide galvanic isolation. With this arrangement, under normal operating conditions neither of the mechanical contacts has to switch off the load current. This means that arcing and contact erosion are virtually eliminated.

Eaton DILDC300/600 hybrid contactors are currently available in two versions, with extensions to the range planned for introduction in the near future. Both versions are two-pole devices and both can be used on systems up to 1,000 V DC. Maximum operating frequency is 100 operations per hour.