PTS Flowbench Forum

Hello I have built the bench and I have wired everything up and I flipped the switch and no motor noise.

I have the phase angle controller and a SSR wired to the hot of one of the 220 legs and from the SSR to one of the 3 wires of the 220 motors ( yes they are 220 lol) the other hot runs from the contractor to the motors other input connection and then the ground wire is hooked to ground.

When I power it up the phase angle controller lights up and as I adjust the 1k pot the light goes brighter and dimmer until it goes off. If I measure the output of the SSR to ground I read 120 volts and if I read across the 2 hits I read zero with them hooked up to the motors when not hooked up they read 246.

I get no motor spin sometimes when I flip the switch the motors have a slight spin maybe 2-3 revs that's it.

Now if I remove the SSR and phase angle controller and I run both hots straight from the contractor to the motor connections the motor spins full speed.

I did not buy the relay or the phase angle controller from Bruce but I did buy the same phase angle controller he sells but have a Amazon SSR ( I know I know it will get replaced soon enough ).

When I read the dc output on the phase angle controller it only goes up to around 11.5 volts with the pot all the way up so it has a range of 0-11.5 with a 1k pot I believe it's suppose to output 24volts.

If anyone can help maybe I'm missing something simple.

I do remember when testing the SSR at work with a 40 volt power supply set from 5-25 volts the SSR didn't want to trip until higher in the voltage range and some times it would flip on off on off on off real fast and I noticed when at 24 volts it worked but I noticed if I turned the power supply on and off sometimes when I came on the SSR didn't want to switch on or took a little time a couple seconds.

I was just using a basic fluke DMM across the outputs when testing the SSR at work.

I also measured across the SSR when on and read 45k ohms which made think something was wrong but reading online says that's normal if reading with a DMM in the ohms setting.

The whole system is wired exactly like the plans show page 28 220 all motor schematic.

Here is a link to the motor spec sheet for the motors I have they are 3 wire 220 volt black white and green ( green is ground on the chassis of the motor)
https://www.ametekdfs.com/-/media/amete ... 6fa2156175
If anyone can get me running I would appreciate it.

What is the exact part number printed on the SSR ?

You need to be very careful buying these, there are two very different types, and its not obvious.
A lot of people here have discovered this the hard way....

One is just the straight on/off type, an electronic substitute for a mechanical relay, which is the most common type of SSR.
These are always a lot cheaper, and are not capable of speed control.

The other far less common (and always more expensive) type is called "random fire SSR" which can be used as a light dimmer or as a motor speed controller.

If it was cheap, I suspect its probably the unusable on/off type.
Here is another clue:

I do remember when testing the SSR at work with a 40 volt power supply set from 5-25 volts the SSR didn't want to trip until higher in the voltage range and some times it would flip on off on off on off real fast

The good motor speed control capable ones are always more expensive
You will definitely do a lot better sourcing these through Bruce.

Watcha got there ?

Thanks for the reply
It is a cheap China one guess I will buy the right one

That's what I get for trying to cut a corner lol.


Ordered a new SSR that is a random fire.

After reading the manual for the phase controller it does say it in there to use a random fire SSR but it was one simple line in the middle of other info.

I would have thought that would be better documented but I guess most people buying those things know better lol.


Thanks again for the reply hope to be running soon.

Great stuff Bearwen.

Its a fine point very easily overlooked, the Devil is in the details.

Just an update the new SSR worked and the bench is working.

Wonderful news !

Merry Christmas, Tony.

Bearwen wrote: ↑Sun Dec 17, 2023 7:46 pm Just an update the new SSR worked and the bench is working.

What ssr did you end up going with? Would you have a link?
I am trying to find a cost effective option to get into NZ.
Cheers.

It looks like Bearwen now has his flow bench going, and is not checking in to the Forum quite so regularly.

Anyhow Mike, the question is not as simple and straightforward as it might appear.

There are no industry wide standard part numbers for these, as for most other electronic parts.
Dozens of different manufacturers worldwide, and each supplies a range of products in different voltage and current ratings, all with their own rather obscure part numbers.

Giving you a specific part number limits you to one specific part, which may be difficult to obtain, out of stock, and even if you can track one down, you will probably have to pay full retail price for it.

If you want to search yourself, look for an SSR and read through the specifications, it must have the words "RANDOM FIRE" in there somewhere.
If not, its almost certainly the much more common and always a lot cheaper normal on/off solid state relay, which is definitely not suitable for speed control.
Bearwen was caught like that, and so have a few other Forum members.

I would give you the same advice I gave to Bearwen.
Contact Bruce and see what he has available. He knows the requirements and bulk buys these in.
He can get a much better price than any of us trying to buy just one single part.

The problem is, that the good random fire SSRs are not only pretty rare, they are also always a lot more expensive because there is a lot more control electronics required inside for the speed control function. And they all look identical from the outside.
If its really cheap its definitely not the right type !

We are all looking to save money, and your best bet will definitely be Bruce.

Cheers for the informed answer Tony, more info and advice is always welcome.

I have been in contact with Bruce and have gone through a few options, the exchange rate is the worst thing about living in this country!

I have a working relationship with 2 of the local electrical and data supply wholesalers but the guys behind the counters got starry eyed when i started asking them, a fait bit outside of their normal range.

So far it is looking like these will be most value for money as far as private imports go, i have been told alot of the EU builds use them and the exchange rate/import levy fees are on the favourable side.

https://cpc.farnell.com/kemo-electronic ... dp/HK01157

What do you think?

I am still in the collecting parts stage so have no panic or urgency.

I have two reservations about that light dimmer module.

Its only rated for sixteen amps, but more importantly the potentiometer very likely runs with one side of the 230v ac supply connected directly to it.
In other words, the potentiometer is not mains isolated but alive.

Mount it all inside a plastic box, and use a generous plastic knob on the metal shaft, for electrical safety or it may kill you.
These are sold as replacement spares for fitting inside plastic appliances that already have all the necessary insulation.

If you are planning on controlling only one or two motors, that should certainly work for you, and be the lowest cost option by far.
Any additional motors beyond that, will require on/off switches, and non return valves fitted.
The instructions for the module say its suitable for motor control, but only with a potentiometer.
Upgrading later to the Forum automatic test pressure controller will not be possible with that module, but it would at least get you started.

Farnell (now called Element14 in Australia) do offer a decent random turn on 50 amp solid state relay with a fully isolated control input, but its $166 Aussie dollars. Farnell N.Z. should have those. You will find other major component houses have something similar also, but at full retail price unfortunately.
https://au.element14.com/celduc/so7650 ... dp/2886603
In addition to that, you will also need the small external circuit board that attaches to the SSR, plus a small 230 to 24v transformer.

That random turn on SSR is comparable in every way to what Bruce is offering, is much safer, a lot more robust, and will work later on with the Forum test pressure controller if you ever decide to upgrade..