OK, now I'm a little more confused about the relay choices. Since I'm trying to do this without an Arduino to control the relays I need NC contacts (I want power to the center EXCEPT when the next block is occupied, which powers the relay coil via the isolated outside rail). Looking at the data sheets for the various Songle relays I see (or don't see) on the modules:
SRD-12VDC-SL-C: 10A relay (rectangular, SPDT), rated for 3A for inductive loads, these are the relays I see on most of the modules. 3A probably not enough? Can I use them at 10A if use a TVS to protect them from voltage spikes?
SRD-12VDC-SL-A: 10A relay (rectangular, SPDT), rated for 5A for inductive loads (best rating I've seen for NC), but I don't see any modules with these.
SLA-12VDC-SL-C: 30A relay (T-shaped, SPDT), NC contacts rated for 0.25 HP at 120 VAC = 1.6 A. Interestingly, even though it's labeled 30A the highest rating for this relay (NO, resistive load) is only 20A. Only the NO SPST relay in the SLA series is actually rated for 30A, even though they are apparently all labeled 30A. Because why would anyone expect the printing on the relay to mean anything?!?
So, based on the data sheets, it looks like the 10A relay that's actually rated for 3A inductive with a TVS added to the contact side would be my best bet. Am I missing something (as I said I have never used a relay before), and will this work long-term? Can I use a TVS to turn a motor into a resistive load as far as the relay is concerned?
