Low warmth 200A relay for renewable micro-power technology


Omron G9KA 800V 200A relay

Called G9KA, its first heat reduction technique is to have a low contact resistance. Its cadmium-free silver-alloy contacts have an initial resistance of 200μΩ (200A for 30min) – contact gap is 4mm (applied to VDE0126).

The second power-saving measure is that the coil has to be operated at one voltage, then held at another.

Two coil versions are available: 12V 28.8Ω (~410mA coil=23°C) and 24V 115.2Ω (~208mA). Both of these are nominally 5W, but reduce to just over 1W once the holding voltage is cut to 45%. The coil is not polarised.

A drop in applied voltage is compulsory: to close the contact, the rated voltage (100 – 120%) must be applied for 100ms to 3s, after which it has to be reduced to 45 – 60% (~1.0 – 1.8W) for continuous operation.

Something to note, is that a series combination of a diode and Zener diode is necessary for spike suppression in the operating circuit. With a diode alone, the relay might not operate correctly, according to page 4 of the data sheet.

The 51 x 51 x 47mm PCB-mount relay is UL recognised, and EN/IEC TUV, UL and CQC Certified. Rated operation is over -40 to +85°C.

With its small size, it is being marketed as a space saving alternative to contactors – intended applications include grid interconnection and safety interruption – although at 85°C, even though it can carry 200A continuously, rated life is only 10 operations if it is asked to break 200A or close 150A.
However, even when normally carrying 200A, life increases to 30,000 operations if make and break currents do not exceed 50A.

“Increasing use of micro-generation from solar and other renewable sources is leading to a growth in distributed power conditioners,” said Omron business development manager Steve Drumm. “Suppressing heat generation has become a major issue for customers in these applications. The structure of the devices, the materials used and the manufacturing quality facilitate the customer’s thermal design.”


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