Relay Carrier for "Sugar Cube" Relays

I would like to use one of your relay carrier boards to operate an Omron G5LE-1-E sugar cube relay to switch a solenoid on and off intermittently. This is a high capacity version of the sugar cube relay that comes with your relay board. Its contacts are rated at 16A switching current. The solenoid is a 12v pulse solenoid but we will be operating it at 35V for extra power. The solenoid coil has 2.7Ω resistance. I have two questions:

  1. I am wondering if the flyback diode/zener diode pair in your carrier can handle the solenoid. They are D3 and D2 in the schematic but the values aren’t given in the schematics. (It looks to me that the zener diode is for the LED.)

  2. I assume I also need a flyback diode across the solenoid that can handle a high voltage and current. The solenoid is powered at 35V and 12.7A. I was thinking this diode would work since its reverse voltage is 600V and average forward current is 60A. Is this way overkill and do you have any suggestions as to how to calculate the specifications required for a particular flyback diode for the solenoid?



The two flyback diodes on our relay carrier should only have to handle the potential flyback current of the coil in the relay, not your solenoid. I do not expect any issues using your relay with the carrier board. The zener diode used in series with the standard diode allows the flyback voltage created by the inductor to be higher (but still safe) which means the residual power in the inductor can dissipate faster and the relay can deactivate faster.

That diode does seem overkill for your solenoid. As a rough guide, the diode should be able to handle at least the normal current and voltage of the solenoid plus some extra as a buffer.