Old thread, but I am considering using relays to enable a type 1 (st5000) controller to run a type 2 autohelm
rotary actuator, and have been thinking through the design considerations.
On the subject of relay contact arcing, and aside from proper contact rating issues for current
and AC vs DC, the contacts will last a lot longer in a DC circuit driving an inductive load like a motor
if they are bypassed by a diode to absorb the inductive kick back. The relay coils themselves should be equipped with such bypass diodes as well, to protect the driving circuitry.
The main downside I see other than the added complexity and points of failure, is the current
draw of the relay coils.
The upside, as opposed to using my own design and construction for a MOSFET circuit, is that I expect relays to be less prone to sudden and inexplicable failure.
It just occurred to me that there are solid state "relays" available, and they might be a less power hungry but still reliable solution.
Any thoughts on this project