Spec-ing a solid state relay?

Thread Starter

Rabbit H

Joined Aug 5, 2016
153
SSRs started coming on the scene about the time that I was changing careers away from industrial electronics in the 1980s; therefore, my experience with them is limited and dated. Sooooooo, I need some help determining what brand/type/model SSR to buy.

I need to switch a combined 110VAC/60CY load consisting of one 1/6hp motor, fourteen 70W halogen PAR 36 spot lights, and two 23W LED floods. The design is such that the motor and 14 halogen spots cannot be ungrouped. I am currently using a Square D 8910DPA23V14 3-pole mechanical contactor rated at 25FLA (resistive) with a 24VAC/60CY coil. (Yes, I know this contactor is overkill in this particular application.) I would like to switch to an SSR in order to reduce the actuator's footprint on the enclosure's backpanel. Reliability is an issue so I need a quality unit. The mounting location is in an outdoor cabinet. The cabinet is rainproof but is not protected against temperature and humidity swings.

Any ideas/suggestions?

Harvey
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
28,698
There are cheap Chinese versions, but I would check out the Opto22 site for N.A. made versions, they have been in business for several decades.
Max.
 

Thread Starter

Rabbit H

Joined Aug 5, 2016
153
Thanks, Kermit, your suggested SSR appears to meet my needs but how do I know if it'll handle the inrush current of the fourteen 70W halogen lamps?

Harvey
 
Last edited:

Kermit2

Joined Feb 5, 2010
4,162
The 40 amp rating is equal to about 4800 watts and the lamps pull about 1000 watts hot.
500% in rush current headroom or almost. Should handle it ok.
 

tcmtech

Joined Nov 4, 2013
2,867
A typical quality brand name unit has substantial inrush current overhead built in so even one rated for 2x the running current would likely not have an issue with as much as 10x inrush current for the first few cycles of every start up.

As for sizing them I go with the 2 x 2 minimum rule. 2x line voltage and 2x running current ratings for minimum unit size. I know many who go way under that but with solid state switching devices overkill is always better especially so if you are using off brand cheap units.
 
Top