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  #1  
Old Fri 23 February 2007, 00:44
Gerald_D
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Solid State Relay (SSR) for switching Router under control of Mach3

Reza asked the following in another thread:

"I am making my board today, and I have some dumb questions. The relay that I got has four terminals marked Input (3 +) and (4 -_) 3-32v
and Output (2 and 1) 24-280VAC. I am using 110 electricity and I plan on using the relay for the router. So I supposed my line voltage will go through terminal 1 and 2 on the output and my switch legs would go through terminal 1 and 2 to operate the relay. It's a Magnecraft (model#SSR225DIN-DC).
The other question is what size fittings are you using going from control panel out carrying the various cables and what type are they (I like them) but I couldn't find them in the local store.
Thanks and I will try to upload some pictures tommorrow."
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  #2  
Old Fri 23 February 2007, 01:16
Gerald_D
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Regarding the relay, I have zero experience of that type (SSR) and I'd better keep my big mouth shut.

Those plastic (or metal) fittings we call "cable glands" and any old electrical shop on the corner has them. But you guys may have a different system or name.
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  #3  
Old Fri 23 February 2007, 01:25
Gerald_D
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What I do know of SSR relays is that PMDX recommended this type for the router. Their PMDX-122 can drive certain SSR's directly. You might want to mail your query and data sheet to them?
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  #4  
Old Fri 23 February 2007, 04:21
Mike Richards
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Terminals 3 and 4 are for the DC control voltage, with terminal 3 normally connected directly to 5VDC and terminal 4 normally connected to an electronic circuit that goes to 0VDC when the relay is supposed to turn on (TTL active LOW).

Terminals 1 and 2 are wired exactly like you would wire the terminals from an AC switch to an electrical outlet. One terminal is connected to the AC Line and the other is connected to the AC Load. The "outlet" is wired so that its AC hot terminal is connected to the SSR's load terminal and its AC neutral terminal is connected to AC neutral.

The way that it works is that when a DC voltage from 3 to 32 volts is applied across terminals 3 & 4, current flows through an internal LED. When that LED turns on, the SSR acts as if an internal switch had been turned on that allows the AC voltage on the Line terminal to be passed to the Load terminal.

An added advantage of this SSR is that the AC side turns on or off as the AC sine wave passes through the zero voltage part of the sine wave, which means that there will NOT be any abrupt surges sent to the router when it is turned on or off.
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  #5  
Old Fri 23 February 2007, 04:24
Gerald_D
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Mike, are these SSR's fairly foolproof if the input polarity is reversed?
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  #6  
Old Fri 23 February 2007, 06:44
Mike Richards
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Gerald,
I've never damaged a SSR by reversing the DC control inputs. All that happened was that the device didn't work. Changing the DC lines to be correct allowed the device to work.

(The Opto-22 brand SSR and the Potter-Brumfield brand SSR have 'steering diodes' built in to keep reverse polarity on the DC side from causing any damage.)

Sometimes the AC side also needs to be wired correctly; however, I haven't used an SSR in almost 25 years where I needed to worry about line and load. If Line and Load are marked on the device, it would be best to connect the Line to the AC HOT and the Load to the AC device.
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  #7  
Old Fri 23 February 2007, 09:54
Mike Richards
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Reza,

Here's a schematic that might help you understand how to hook up a Solid State Relay to the PMDX-122. If you're already using PMDX's J8-2 for another device, you can substitute J8-3 or J8-4 for J8-2. Of course, you'll have to 'turn on' the ports by correctly setting up the pins in Mach3.


(Many thanks to Gerald for converting my bitmat schematic to GIF.)
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  #8  
Old Fri 23 February 2007, 10:11
Gerald_D
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Here is the PMDX-122:



J8 is at the top right. J8-1 is the "+5V Aux Out" and J8-2 is the "Pin 14". As Mike says, you will have to tell Mach3 (Config > Ports & Pins) that your router is at Pin 14.

The PMDX-122 has a relay built in on the card, but this is limited to 10 Amp only - you could not drive a 15Amp router from this. But you could use it to drive a bigger relay (or contactor) that will handle the 15 Amp.
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  #9  
Old Fri 23 February 2007, 17:06
reza forushani
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Can we use the built in relay for the power to other stuff (other than router)?
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  #10  
Old Fri 23 February 2007, 21:44
Gerald_D
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Yes, it is there on the PMDX-122 for your convenience (It is the black cube in the bottom right corner). But the contacts can handle 10 amp max....and it is not easy to replace if you burn it.

Accessed at J7. Typically "line" would go to "Rly Com" and "load" would go to "N/O"
Under Mach3 ports&pins this is Pin 1.
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  #11  
Old Fri 23 February 2007, 22:10
reza forushani
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I just pluged the PMDX board into my USB bus just to power up. Some LEDs like 3 are on and some like 7 and 9 are blinking.. LED# 5 is not on or blinking. Is this normal?
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  #12  
Old Fri 23 February 2007, 22:15
Gerald_D
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In general LED's on or blinking is normal, smoke is not normal.

Seriously though, I don't remember the numbers and first behaviour - play with it a bit longer to see if you really have a problem and then maybe we can spend time in my dusty brain.
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  #13  
Old Fri 23 February 2007, 22:39
reza forushani
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Right I just used my usb port for power. This computer does not have parallel port. I will use another computer with Parallel port tommorrow and let you know which lights (LEDs) blink on start up.
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  #14  
Old Sat 24 February 2007, 22:49
reza forushani
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Mike or Gerlad, I think the relay is not working right. Passing half the voltage when it is off and full voltage when it is on. IAm I doing somerthing wrong?
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  #15  
Old Sat 24 February 2007, 23:01
Gerald_D
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Reza, that is normal for a "SSR" type relay. That is one of the reasons I have never used them (the other reason is the price over here). Apparently they are perfectly okay with routers.
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  #16  
Old Sat 24 February 2007, 23:21
reza forushani
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You mean it's OK
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  #17  
Old Sat 24 February 2007, 23:23
Mike Richards
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Reza,
Gerald is right, a SSR 'leaks'. So if you read the voltage with no load connected to it, you'll get a false reading.

I've used SSRs for years in all kinds of process control situations and never had a problem when I used an SSR; however, a SSR will leak enough current to give you a good 'tingle' so be sure to either turn off the power or use a mechanical relay/switch as a fail safe device to cut all power from the circuit.
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  #18  
Old Sat 24 February 2007, 23:40
Mike Richards
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"Also something is not right with my relay. I used a light bulb to check it out. When it is energized (LED on with 24v) the bulb is on. When LED is off (no control voltage) the light bulb is half lit. I checked with an ohmmeter and I get 120v when LED is on and 60vac when LED is off. Shouldn't it not pass anything when the relay is off?"

Reza,
I should have read this thread before responding on the other thread about your SSR. Something is NOT right. You should not have 60 VAC when then SSR is OFF and when you have a light bulb connected to the load.

Have you checked the wiring to make sure that you have everything wired correctly? (Even with 30+ years of experience, I still FREQUENTLY make wiring mistakes.) Be sure that the control inputs are NOT floating. When the relay is OFF, both the + and the - inputs should be at the same voltage. (Depending on whether you are SOURCING current or SINKING current, both inputs could be at 0-VDC or at 24-VDC.)

Also, some SSR require an additional resistor to be put in series with the control voltage + connector if you're using a voltage higher than 5VDC. A opto device usually needs about 10ma to turn fully on, so a 5V circuit would use a 390 ohm resistor (remember that the LED will drop about one volt), a 12V circuit would use a 10 to 12K resistor and a 24V circuit would use a 22K resistor. The Potter-Brumfield SSRs that I use don't require an external resistor, but it's always good to check the documentation to make sure.
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  #19  
Old Sun 25 February 2007, 00:41
reza forushani
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Right now I am just playing with things. Feeding one leg per your drawing into the relay (110v). Connecting a regular light (110v bulb) when the LED is off the light bulb is half lit. When the LED is on (voltage applied either 9 or 24v) the light bulb is full on. I was going to use a status light on the relay through the control panel door, showing no voltage passing through the realy or voltage being present. But with this relay's leak and light being dim or bright, that's not going to work. I guess either I'll use a different relay or something.

What relay are you guys using?
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  #20  
Old Sun 25 February 2007, 01:11
Gerald_D
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Somehow people don't worry about the leak. I like your relay - I like also that you are the guinea pig on another continent...

What I would try out here: Leave the light connected. connect a solid wire (paper clip) across the + and - input. See how the bulb glows. (oh yes, make sure it is an old-fashion high current bulb). Measure the bulb voltage.
Then connect a 9v battery over the + and - and see what happens. Tell me if you are going to try this - I want time to crawl under the bed and put my fingers in my ears.
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  #21  
Old Sun 25 February 2007, 02:30
reza forushani
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YES. I will try anything. Worst case I have to buy more fingers.
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  #22  
Old Sun 25 February 2007, 13:06
Mike Richards
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Reza, you've really got me puzzled. I just connected an old grayhill SSR to a light bulb, just like you described. I used a nine-volt battery, just as Gerald sugested. Everything worked perfectly. With the battery disconnected (nothing attached to the input terminals) the light bulb was OFF. With the battery attached to the input terminals, the light bulb was ON.

When I looked that the catalog page for the SSR that you're using, it states that the leakage current for the 225DIN-DC model that you're using is 10mA, which would not be enough current to light up a light bulb. The minimum load current has to be at least 120mA, so you probably can't use that SSR to drive an indicator lamp, but, with the 25-Amp rating, it would be more than adequate to run a router.

Tomorrow when I can get a few other parts, I'll try another experiment or two to see if I can figure out why your SSR is behaving the way that it does.
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  #23  
Old Sun 25 February 2007, 13:13
Gerald_D
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Mike, I am suspicious that he used some fluorescent type lamp (maybe with electronic "excitation") which sometimes start glowing under mysterious circumstances. And I suggested the paperclip to make sure there is no difference in voltage between the input terminals. My feeling is that relay is absolutely perfect for the router, and that it will work fine when connected to the PMDX-122.
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  #24  
Old Sun 25 February 2007, 14:05
reza forushani
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Gerald

I emailed a couple of pictures I couldn't upload.
It shows the light bulb and relay set up.
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  #25  
Old Sun 25 February 2007, 14:25
reza forushani
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I had an electrician check things out and we have concluded that the realy is BAD. We will order another relay and test it and let you know.
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  #26  
Old Sun 25 February 2007, 22:59
Gerald_D
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Got the pic, thanks.




That "light bulb" looks suspiciously like a neon indicator lamp. Try and change it for a real light bulb, or a power drill, or something else that really draws a lot of power.
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  #27  
Old Mon 26 February 2007, 01:20
Gerald_D
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Looked a bit more at neon indicator lamps and it would appear they run off the 10mA leakage current that Mike spoke of. This example of a data sheet says to add a 47k series resistor to a 125V indicator used on 250V - that means this example only draws 3mA! I don't think your relay is faulty. Explain my theory to your electrician and see if he changes his opinion.
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  #28  
Old Mon 26 February 2007, 01:42
reza forushani
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You are right. We used a radio/clock and it would not turn on. The little LED uses very samll amounts and that's why it glows a little. So we should be fine with the relay. Thanks to you and also Mike for his patience and testing the relay. I was going to mount this LED on the door to indicate power flowing through the relay but that is not going to work, so I have to come up with another solution for that.
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  #29  
Old Mon 11 June 2007, 07:06
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by Art View Post
The AC outlet is controled by a solid state relayid that turns on with a M03 command and turns off with M30 command. This turns on/off the dust collector and router. Interesting fact on solid state relays is that they need to have a load on them to work. This led to some real head scraching when the lamp I used in testing worked and when the router and DC were plugged in they worked but when the electronic controled router by it's self didn't work.
An very important observation. Some (electronically-controlled) routers will not be switched on by a solid state relay. You will need to give the relay extra load. Like adding a lamp to the circuit.
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  #30  
Old Mon 27 August 2007, 10:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
And Art Ransom is discovering that sometimes he can't turn the solid state relay off!

Reference

"I use M3 to energize a solid state relay which applys 120V to router and dust
collector. M30 turns them off. Normally everything works great. Ocasionaly
they fail to turn off. Once this happens, reruning the program fails to turn
them off. Usually if I unplug both of them and wait 30 seconds and plug them
back in the power has dropped om the plugs and everything is back to normal.
Also if machine hits a limit switch they fail to turn off."
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