# Unusual "Back to the Future" project



## McClary’s Electrical (Feb 21, 2009)

varmit said:


> i just finished a rare project for these days: A fully automatic batching system with all relay logic- no PLC. This is what the plant requested, so my thought was, "If they want to pay me to do it, it is a great idea". I did the design and installation. Everything worked just fine.
> 
> I originally installed the system two years ago as a semiautomatic system. I tried to convince the plant owner then to allow me to put the system on a PLC . He wanted relay logic then and again this time. So I did as requested. To make everything function properly required the use of 34 relays, 8 timers and 5 loop controllers. I thought that I had been time warped to the 1970's. It was a nice mental exercise. It has been a long time since I have done that much relay logic. My old brain must still function. Of course logic wise, PLC or relays are about the same, but the relay logic is a lot more hardware intensive and if you make a mistake it can be a lot more work to fix.


 

This is really disappointing he wouldn't let you install a PLC. You blew enough on relays to do it, and troubleshooting will be a nightmare.


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## varmit (Apr 19, 2009)

I agree. This was definitely not a money saving plan. I do not know what the owners thinking was. He said none of his folks understand PLC's, but they don't understand relays either. I suppose that I have job security at this plant.


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## BBQ (Nov 16, 2010)

When that big EMP pulse comes he will be the only one left in business .... assuming he has a non-electronic controlled power source. :jester:


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## Wirenuting (Sep 12, 2010)

varmit said:


> I agree. This was definitely not a money saving plan. I do not know what the owners thinking was. He said none of his folks understand PLC's, but they don't understand relays either. I suppose that I have job security at this plant.


I've don't that here for a few projects. 
PLC's are nice until someone who is clueless needs to make a repair. And swapping a bad relay takes only seconds. 
There is a place for both in the world. 

With your time and his money,,, anything is possible.


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## captkirk (Nov 21, 2007)

Wirenuting said:


> I've don't that here for a few projects.
> PLC's are nice until someone who is clueless needs to make a repair. And swapping a bad relay takes only seconds.
> There is a place for both in the world.
> 
> With your time and his money,,, anything is possible.


 Is that a B29 ball turret


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## Wirenuting (Sep 12, 2010)

captkirk said:


> Is that a B29 ball turret


B-17 ball turret.
B-29 were not manned. They were remotely operated.


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## varmit (Apr 19, 2009)

Wirenuting said:


> B-17 ball turret.
> B-29 were not manned. They were remotely operated.


Are you a Warbird fan also?


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## Wirenuting (Sep 12, 2010)

varmit said:


> Are you a Warbird fan also?


Not really. I like WW2 naval warships. I was a gunnersmate and love the freedom of the seas. It was nice to kick back on a darkened ship on a moonless night and read by the light of the stars. 
Just wish we had a radio controlled ship battle club around here. 

I snatched the turret pic because of the baby in the ball. He knows what he wants to be when he grows up. I wanted to be a ball turret gunner when I was little. Ahh,, what a view they had. Not counting the times were the ball got stuck and the wheels wouldn't go down.

Of course everyone knows the B-17 was the best bomber and the P-38 the best fighter.


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## Jlarson (Jun 28, 2009)

What no pictures? :laughing: 


Relay logic defiantly still has it's place. I've done stuff were we had PLC's then had a redundant relay back up system, that could take over in case the controller bit it.


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## guest (Feb 21, 2009)

varmit said:


> I agree. This was definitely not a money saving plan. I do not know what the owners thinking was. He said none of his folks understand PLC's, but they don't understand relays either. I suppose that I have job security at this plant.


Exactly, and to maintain that security, you need to do what the customer wants, as long as they are willing to pay for it and it is Code-Compliant. Personal preference is not an option sometimes. 

For the new wave of digital cinema, I personally HATE Sony's projectors and servers. But if that's what the customer wants, that's what they get and I install it. (Then I go home and beat my head against the wall. :wallbash: )


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## MDShunk (Jan 7, 2007)

I worked on a plating line that had relay logic control panels 6' tall and nearly 40' long to run the line. That was pretty special to work on. Good prints were a must. If you studied the print for 15 minutes or so before you started to troubleshoot your problem, you could pretty much nail the 6 or 8 things that you needed to check, and one of them generally showed your problem. If not, you just studied the prints some more. If you don't have prints to a bigger relay logic panel, you might as well ring out and go home because someone threw you under the bus.


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## MDShunk (Jan 7, 2007)

Jlarson said:


> What no pictures? :laughing:
> 
> 
> Relay logic defiantly still has it's place. I've done stuff were we had PLC's then had a redundant relay back up system, that could take over in case the controller bit it.


I see that a few of the manufacturers have provisions for automatic hot standby PLC's.


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## Jlarson (Jun 28, 2009)

MDShunk said:


> I see that a few of the manufacturers have provisions for automatic hot standby PLC's.


Yeah but I think the relay back up was more of a it's gonna work no matter what, it's pretty much bullet proof type of thing.


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## MDShunk (Jan 7, 2007)

Jlarson said:


> Yeah but I think the relay back up was more of a it's gonna work no matter what, it's pretty much bullet proof type of thing.


Yeah, probably great for a pumping station or something like that. If you were PLC controlling your oil refinery, for instance, a hot standby PLC would be a lot more appropriate. Relay logic for that would fill a small house. :thumbsup:

By the way, how the heck do you send something like a 0-10V or 4-20ma process follower signal to a VFD when using relay logic?


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## Jlarson (Jun 28, 2009)

MDShunk said:


> By the way, how the heck do you send something like a 0-10V or 4-20ma process follower signal to a VFD when using relay logic?


You don't I guess. Never really had such a thing come up. I almost did with a project to retro a water district with VFDs and chlorination with back up relay logic for the PLCs but it never got past the rough planning stages.


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## MDShunk (Jan 7, 2007)

When I thought about it more, I figure if you're switching to the backup relay logic, you'd probably just start your pumps across the line and short cycle or plug them to eliminate the VFD.


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## varmit (Apr 19, 2009)

MDShunk said:


> Yeah, probably great for a pumping station or something like that. If you were PLC controlling your oil refinery, for instance, a hot standby PLC would be a lot more appropriate. Relay logic for that would fill a small house. :thumbsup:
> 
> By the way, how the heck do you send something like a 0-10V or 4-20ma process follower signal to a VFD when using relay logic?


I use the 1/8 DIN loop controllers. Of course, these are essentially a small PLC. I use a lot of these controls on small stand alone equipment.


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## Jefro (Jul 28, 2009)

MDShunk said:


> I worked on a plating line that had relay logic control panels 6' tall and nearly 40' long to run the line. That was pretty special to work on. Good prints were a must. If you studied the print for 15 minutes or so before you started to troubleshoot your problem, you could pretty much nail the 6 or 8 things that you needed to check, and one of them generally showed your problem. If not, you just studied the prints some more. If you don't have prints to a bigger relay logic panel, you might as well ring out and go home because someone threw you under the bus.


There are old elevators in my building with those 6' by 6' relay panels. You can stand in front of them for a good long time trying to figure out what's going on...


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## oliquir (Jan 13, 2011)

geez i would stop working for that company, i hate when client ask for old fashion stuff, new technician wont be able to troubleshout those systems in few years, they just dont learn this anymore


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## JRaef (Mar 23, 2009)

Worst* job I ever did was a bunch of control panels inside of a dam on the Columbia River for the Army Corpse of Engineers (misspelling is intentional).

24 control panels controlling Submerged Traveling Screens. NO PLC was allowed, they insisted on all relay logic and they would not accept plug-in relays, so each panel had 148 machine tool relays, some with up to 8 poles. Added insults were the requirements for extra flexible wire with SIS insulation, which at the time was ONLY available in gray, and ring tongue terminals with heat shrink 12 digit wire numbers on EVERYTHING. So because the SIS was only gray, for each neutral connection (everything was 120V control of course), we had to shrink on a 6" while sleeve (no tape) and then a wire number. Because of the Ring Tongue requirement, we couldn't use DIN rail terminals, we had to use the old style Buchannan blocks that were twice as big. The final blow was a size constraint on the enclosure because they were going inside of the gallery, essentially a lengthwise tunnel in the dam. My hands have still not recovered from that project, and that was 20 years ago.

*In this aspect...


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## Jlarson (Jun 28, 2009)

oliquir said:


> geez i would stop working for that company, i hate when client ask for old fashion stuff, new technician wont be able to troubleshout those systems in few years, they just dont learn this anymore


Well that's a stupid reason to stop taking a client's money.


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## oliquir (Jan 13, 2011)

Jlarson said:


> Well that's a stupid reason to stop taking a client's money.


well i dont make jobs that i dont want to troubleshoot in the future


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## MDShunk (Jan 7, 2007)

oliquir said:


> well i dont make jobs that i dont want to troubleshoot in the future


Lucky for me that there are guys like you. :thumbsup: I think you are either very short-sighted, or just someone's employee talking out of your ass. In any event, it doesn't really matter. There are plenty of us guys that are "selling whatever it is that they're buying".


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## Frank Mc (Nov 7, 2010)

varmit said:


> i just finished a rare project for these days: A fully automatic batching system with all relay logic- no PLC. This is what the plant requested, so my thought was, "If they want to pay me to do it, it is a great idea". I did the design and installation. Everything worked just fine.
> 
> I originally installed the system two years ago as a semiautomatic system. I tried to convince the plant owner then to allow me to put the system on a PLC . He wanted relay logic then and again this time. So I did as requested. To make everything function properly required the use of 34 relays, 8 timers and 5 loop controllers. I thought that I had been time warped to the 1970's. It was a nice mental exercise. It has been a long time since I have done that much relay logic. My old brain must still function. Of course logic wise, PLC or relays are about the same, but the relay logic is a lot more hardware intensive and if you make a mistake it can be a lot more work to fix.


To be 1970,s compliant no slotted duct ;-) or cable ties....All cables laced ;-)..........

Good work on getting it going as you would know there,s no room for error when designing relay logic..a mistake could be very expensive....
Frank


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## Frank Mc (Nov 7, 2010)

oliquir said:


> geez i would stop working for that company, i hate when client ask for old fashion stuff, new technician wont be able to troubleshout those systems in few years, they just dont learn this anymore


Well there,s lots of relay logic still around so i guess us older blokes can still make a quid servicing old reliable gear....

Frank


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## varmit (Apr 19, 2009)

Frank Mc said:


> Well there,s lots of relay logic still around so i guess us older blokes can still make a quid servicing old reliable gear....
> 
> Frank


I sure hope so.


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## CHECKtheE-STOP (Jan 17, 2011)

MDShunk said:


> I see that a few of the manufacturers have provisions for automatic hot standby PLC's.





MDShunk said:


> Yeah, probably great for a pumping station or something like that. If you were PLC controlling your oil refinery, for instance, a hot standby PLC would be a lot more appropriate. Relay logic for that would fill a small house. :thumbsup:
> 
> By the way, how the heck do you send something like a 0-10V or 4-20ma process follower signal to a VFD when using relay logic?



I am a fairly young service/maintenance electrician with an uncanny nack for troubleshooting relay logic. I personally prefer it over programable logic, mainly due to the fact it is a dying technology and not too many sparkies in my area care for the challenge and has proved to be a lucrative source of job security, despite the poor economy. I have however have been forced to get with the times and get into the anolog and digital silicon based control world! The troubleshooting is far more clean and less puzzling but doesn't pose the same challenges..... I also find myself buying flash drives by the case and only toting a laptop, cables, a meter, a precision screwdriver, and a Klein 11 in 1. All in all it kind of makes me feel like a cowboy on a cattle drive competing against the tractor trailers hauling beef at 55mph! My current place of employment has talk going around about changing over from device net, control net, and rio to web net.... I have reservations about the security of it all but would appreciate any input on web net from anyone that has experience with it.


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## CHECKtheE-STOP (Jan 17, 2011)

MDShunk said:


> Yeah, probably great for a pumping station or something like that. If you were PLC controlling your oil refinery, for instance, a hot standby PLC would be a lot more appropriate. Relay logic for that would fill a small house. :thumbsup:
> 
> By the way, how the heck do you send something like a 0-10V or 4-20ma process follower signal to a VFD when using relay logic?



If you are using a digital or anolog transmitter to control the vfd you can wire it straight to the drive and set up the drive from sync to source as to power the transmitter. Next program the parameters to fit the application. I have successfully done this with several AB powerfelx 4's, 40's, 70's and anolog transmitters such as level, pressure, flow, temperature and conductivity transmitters. I am not sure however about transmitters that use a pulse output.


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