silicon controll rectifier (SCR) or solid state relay (SSR)

[watercooler]

Hello everyone I am gathering parts for my flow bench and for some reason I don't know which one to get for my flow bench to control motor speeds.The SSR seems to be the most common and it is widely used on AC motors and the SCR is very scarce especially when looking for one thats 70 amps or up and this is mostly used on DC application.I have found a SSR at a good price and would be using a PWM to control the SSR or SCR and in turn control motor speeds,I have found these parts on ebay and would like to know what everyone thinks? will this setup work powering 7 924w motors?

Here is the SSR:
http://www.ebay.com/itm/CRYDOM-RELAY-CW ... 2a22d90602

Here is the controller that will power the SSR:
http://www.ebay.com/itm/261078222328?ss ... 1438.l2649

On Bruce old forum a guy got all his parts from HB Controls that brought his total to $270.I am looking for a solution thats much cheaper than that and will keep cost down because its a hobby project of mine.

[Tony]

The Crydom CWD24125-10 is the correct part, and at a pretty good price too.
This is a 125 Amp random fire SCR module, which is exactly what you need.

The motor speed controller appears to be for directly controlling low a voltage dc motor, and will not work with the SCR module. Give it a miss!

[watercooler]

So Tony its a SSR with a SCR out?,thanks for responding and the help but what small circuit do I need to control it?

[86rocco]

A solid state relay is functionally the same as two SCR's back to back along with a little bit of additional control circuitry. The SSR you've selected is a random turn-on type which should work nicely. I'm not is a position to comment about the remaining parts.

[watercooler]

A solid state relay is functionally the same as two SCR's back to back along with a little bit of additional control circuitry. The SSR you've selected is a random turn-on type which should work nicely. I'm not is a position to comment about the remaining parts.

That sounds like I got one thing right so far I just really want to know what can I use to control the SSR and I am thinking a PWM would do the trick but I am still awaiting confirmation.

[watercooler]

May this temperature control pid unit?
http://www.ebay.com/itm/New-PID-Digital ... 3f1d8c5889

[Tony]

That PID controller is something very different again, and not for us.

What you need is the small control circuit board manufactured by HB Controls. That is what everyone here uses, and is perfect for the job.
You will also require a heat sink, and a small 24 volt transformer to power the HB Controls circuit board.

[watercooler]

That PID controller is something very different again, and not for us.

What you need is the small control circuit board manufactured by HB Controls. That is what everyone here uses, and is perfect for the job.
You will also require a heat sink, and a small 24 volt transformer to power the HB Controls circuit board.

Hmmmmmmm, so Tony don't that unit uses pulse to control voltage? I just think that I could buy or make a circuit that could operate the same, I am still doing some research and came across this Pulse Control Module thats design for SSR take a look

http://www.ebay.com/itm/Omega-SSR-Serie ... 23245d1da9
and here is the datasheet on it,its 2 to 20 mAdc ranging from 0% to 100% I would just need a driver to drive it?
http://www.omega.com/manuals/manualpdf/M0957.pdf
Sorry for being so hard headed but I just think there is a cheaper solution than spending a bunch on a controller and do they sell it separate from their SSR? I will check again and see if they do and thanks to you and everyone input its very valuable.

[Brucepts]

You need to figureout what it takes to control the phase angle control module that is attached to the SSR.

On the one I sell it allows various inputs such as POT, Volts and PWM. I tried to research the phase angle control on that SSR but found no info on it. Looks to be an older model as the one I supply uses DIPs to make the input changes.

You will also need a transformer so you also need to figureout that part too.

That is a GREAT price if you can figureout what control input it wants and the transformer. I sell my setup for $245 currently and this changes based on the parts I track down and what it costs me to build mine.

[Brucepts]

If I was greedy I'd buy all he has and figure it out and flip'em . . . but that would not be the DIY spirit