Those look like useful little devices, Lee, and a good price. One thing that they never seem to tell you, though, is the coil operating current which would be useful for the OP trying to decide if his 24V PSU has the spare capacity to operate it. Personally, assuming that transformer switch-on doesn't trip the supply breakers, I wouldn't bother with a soft-start at these relatively low power levels and just switch directly. Mine seems fine without (650VA toroidal).

Here's a question for the gang, though. Like a lot of small contactors, this is designed to handle 3-phase and therefore has 3 main N/O contacts. If you are using it on single phase, would you just use one contact, wire all three in parallel, or all three in series?