Is it possible to substitute an SCR power controller with a relay/contactor?

Thread Starter


Joined Dec 16, 2016
Hi folks,
I have an SCR SSPC controller that I got recently. This is the first time I actually got to play properly with an SCR controller.

The specs of the SCR SSPC are:
WATLOW DB20-24CO-0000
Input trigger : Pin 7&8 @ 4-32VDC
Mains Input: Pins 1,2,3(3-phase)/ 1&2 or 2&3 (single phase)
Mains output: Pins 4,5 &6.
Rated current :25 Amps
Input voltage: 100~240V

The input trigger I've used is a fully charged Li-ion cell at 4.17V at PINS 7&8. According to these specs, we can obtain a small and higher current relay which is smaller or even a contactor. The SPC is very bulky and heavy with all the metal sink.

So, is there any advantage of using an SCR SSPC over a relay? Also is an SCR SSPC same as an Solid State Relay?



Joined Jul 18, 2013
That's not your average SSR, that is for switching 3ph with back-to-back SCR's for 3ph loads motors etc.
SSR is Solid State Relay. SSRPC Solid State Power Controllers.
The one advantage that I can see is that you do not get contact arcing or degradation.
These are very similar to solid state soft starters for 3 ph motors.
Last edited: