Omron G9KB bi-directional DC power relay

“It will be particularly beneficial where electricity from solar panels is being used to charge an electric vehicle,” said Omron marketing manager Steve Drumm.

Called G9KB, it is a single pole single throw normally-open device that, according to the company, can replace two standard uni-directional relays in this type of application.

The (Cd-free) silver double-break contacts are rated to switch the full 50A maximum carrying current at the maximum voltage of 600V. Arc suppression “stretches the arc using the magnetic force of a permanent magnet placed near the contact point”, said Omron.

Contact life is 2,000 operations at full rated current and voltage (resistive load, 85°C), this climbs to 6,000 operations at 40A.

The coil is non-polarised, and comes in two versions: 12V (51Ω) or 24V (206Ω), consuming ~2.8W at full voltage and holding at ~700mW.

Drive to the coil must be in two stages: 100% of nominal voltage for 100ms to 3s, thence at between 45 to 60% for the remaining time the contacts are required to remain closed.

Externally, both a diode and zener diode are required in anti-series across the coil, with the Zener rated at three times the coil rating, and the diode withstanding 10x the coil rating in reverse. The “diode is for coil surge absorption”, said Omron. “Ensure to include Zener diode as there is a possibility of any influence for switching capability when only using diodes.”

The relay has a footprint of 50 x 37mm and stands 50mm above the PCB but “secure an installation gap of 20 mm or more for the product”, according to the data sheet. Weight is 110g, so be careful that the PCB is strong enough.

The G9KB product page can be found here, and the data sheet here.