The scheme shown is for an endurance rig to cycle four independent and identical solenoid valves 10million times. And during this I need to capture the shift time of each valve to see if its degraded. Shift Time = Time between 24V dc command and full shift of the valve spool.

Basic functionality acheived and I get 220 to 230ms if I operate only one solenoid ( say SOL_A ) . But the moment I switch ON one more solenoid ( B, C or D ) the shift times of both solenoids increase by about 40ms and read as 260ms.

Unfortunately I cannot try out more than 2 solenoids at a time as of now and I really cant say what will happen then.

Each SSR is rated for 10A and how can it behave differently for 1.25A load and 2,5A load ? Or is there some mistake in the set up ?? Though not shown, I have a IN4007 diode across each solenoid.

Can someone point out why is there a increase in shift time ( which means the rate of rise of 24V dc is sluggish )


Thanks

Raghu