handle wild leg

I've been drill and tapping all day, mounting components in my refit mill drive control cabinet.
I'm wiring the machine so I'll have two hot legs when the phase
converter is off. That way the control computer can run.
I want to drop Estop if power to the "wild" leg is missing. if I just use a small 110 volt coil relay <from hot to neutral>, I think it will burn out with too much voltage. Correct? How would you handle?
Also, I'd like the computer to monitor all three phases through Opto 22 inputs: http://www.opto22.com/site/pr_details.aspx?cid=4&item=G4IAC5
Again, the wild leg could go over 140. How do I handle it here?
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Use AC rated solid state relay?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 16 Oct 2010 17:56:45 -0500, Ignoramus11321

You may have something there Iggy. http://www.opto22.com/site/pr_details.aspx?cid=4&item 0A10
If I'm reading right it will take up to 280 volts AC and go on at 85. Correct?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/16/2010 11:33 PM, Karl Townsend wrote:

A couple of things to consider on those solid state relays, You probably want ones designed to switch a DC load and you are going to have to meet the minimum load current.
All of the solid state relays I have used that are designed to switch an AC load will latch on once the control voltage goes up enough. They will switch off when the load current goes through zero on an AC load. If you are using them to control a signal into a computer, it will probably be a DC signal, so it will not switch off, even if the AC control signal goes away.
Another standard feature of solid state relays is that they have a minimum load current to switch on at all. I think it is related to how the load side of the optical isolation is powered. Driving a control signal into a computer input port probably will not provide that load. A pilot light probably would be enough, but look at the data sheet on the relay for sure.
BobH
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 16 Oct 2010 19:26:13 +0000, BobH

Thanks for pointing this out. I didn't know this, makes sense.
karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 16 Oct 2010 19:26:13 +0000, BobH

I also used to apply a resistor across the input side to bleed off any charge buildup. Otherwise, they'd fire every once in a while. OK for heaters, not for motors. I also never used them in a safety application for that reason.
Pete Keillor
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I did not check that particular model, but yes, exactly that sort of thing. They are very forgiving of input voltage.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 16 Oct 2010 18:33:29 -0500, Karl Townsend

Like killing flies with napalm, but it'll work. "Off" leakage current is 14 ma. Have this Opto22 device switch 120VAC from line to a small relay, switch Estop with that relay.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 16 Oct 2010 23:05:48 -0500, Don Foreman

Thanks for pointing out the load requirement.
OK as a separate issue, I'd like the control computer to know the phase is present. the spec on the G4 module say 90 -140 volt and 28K resistance. Is this a simple ohm's law thing where i could add 9.3K resistance to still have 120 volt trip this module and get up to 190 without damage?
http://www.opto22.com/site/pr_details.aspx?cid=4&item=G4IAC5
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 17 Oct 2010 06:30:24 -0500, Karl Townsend

Yes.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

    [ ... ]

    Where are you getting the 28K spec? I don't see it the URL.
    But -- as I described in a previous posting in this thread, I remember seeing the circuit as a (starting at one input terminal) a resistor, a bridge rectifier (with the other side of the bridge going to the second input terminal) and the DC output of the bridge going to the LED side of the opto-isolator, so yes, this should scale pretty linearly to an added resistance in series with the input.
    If in doubt -- experiment. Try it with a 240 VAC signal instead of the 190 you're worrying about. A short term application should suffice to make sure that works. If it fails, you are out $12.50 (keep the computer interface disconnected from the board into which the module plugs -- and don't have any other modules present. (You will need a 5VDC input to the board, to power the module.)
    You can judge when it switches using the LED on the corner of the module. Then take the power down to 120 VAC and see whether the switch still sees it. If it does not -- take a Variac to vary one side of the 240 VAC line and adjust until you see where it comes on, and where it goes off. (Remember, they mention having a hysteresis amplifier on the input).
    Good Luck,         DoN.
--
Remove oil spill source from e-mail
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
say, sittin' here musing and drinking coffee.
What if i had an SSR fire a 220 coil relay? Then loss of any phase would drop Estop. correct? Makes it seem like less of a kludge to me anyway.
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I really don't understand why you are struggling with this - it is a little complex to make a true "phase loss" detector, but it is trivial to make a voltage monitor that will provide a signal when any of the three legs drops below a preset value with respect to any of the others for more than a half cycle. If you don't have the electrical knowledge, many of us do, you are talking $5 worth of parts and some time soldering stuff. Then you can do whatever you want with the signal - what you are doing here is using a pile of expensive already assembled parts to do something they were not intended to do - you might get it to work, but it is kind of like using a massey fergeson tractor to warm your swimming pool. all you need are three voltage comparators, which you diode OR together - one chip, some resistors, 6 diodes, 6 capacitors, a power supply chip and so on - this is a box that would be about the size of a cigarette pack, worst case - and your control circuitry probably already produces suitable power forms - you only need a fraction of a miliamp of power

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 17 Oct 2010 08:31:22 -0700, "Bill Noble"

Karl doesn't like to assemble electronic stuff. You probably don't make much .308 ammunition. We all have our preferences! <G>
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 17 Oct 2010 12:14:14 -0500, Don Foreman

Don even made a special trip out here to teach me circuit board soldering and had me going pretty good after an hour. But it didn't take, my next effort was useless. Now, I just found out a couple months ago that my neighbor of 15 years (he's still new here) is good at it. But, he's working 6-7 days a week, I won't ask for this.
Nothing wrong with using a sledge hammer to swat a fly if its not too expensive and its reliable.
Now, I am truly addicted to the .308 cartridge and especially the semi auto rifles that use them. Here's what Santa can get me for Christmas: http://www.lwrci.com/p-120-repr.aspx
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 17 Oct 2010 12:49:25 -0500, Karl Townsend

One assumes you want the 20" heavy barrel, right?
Sigh..be glad you dont live in California
They are Banned here...damnit
Gunner
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Sence I'm dreaming, I also need the ACOG gunsight and a spare 12" barrel to go with that 20" barrel <VBG>
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Santa alreade gave me a 91/30 Mosin Nagant. :)
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 17 Oct 2010 16:30:28 -0500, Ignoramus15216

Would you rather have Santa give you a $3,700 rifle or the $89 one you got, hmm?
-- Know how to listen, and you will profit even from those who talk badly. -- Plutarch
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am not sure, cannot make up my mind, it is not that I really need either. I just wanted a rifle like in the movies. I already have enough decent shooting rifles.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.