garp66 wrote on 1/6/2020 5:01 PM:
A solid-state relay (SSR) uses a semiconductor device as the electrical contact.
The voltage drop across the device varies with the contact current and
hence could introduce an error. A clunky old mechanical contact is
better in this respect.
If you were starting a curve-tracer design, you could investigate SSR properties
and possibly compensate for errors, but retrofitting SSRs in an existing
curve tracer would be messy,