In article , "Scrim" wrote:
I have a Watlow F4 Temperature controller (full Part No. F4PH-CAAA001RG). I
want to connect a solid state relay to its "Switched DC" output so I get
zero crossing switching but I'm unsure if this requires a SSR with random or
Zero Crossing switching. The manual doesn't help:
http://www.watlow.com/literature/pro...ers/f4pe_d.pdf

The F4 manual does mention "Burst Fire" which uses zero crossing detection,
so I suspect that the switched DC output can drive either type of SSR so
long as the controller and SSR are connected to the same mains supply so the
phases are matched.

Or have I misunderstood what's going on?

I don't even know what their ramp and soak mean. When I use a linear ramp
controller, I feed the DC control voltage to a Mosfet to control voltage linearly.

Yes, a SSR with zero crossing turn on at the zero point, and off at the zero point.

We use linear ramps so it has no switching noise.

greg