# Control design



## Wirenuting (Sep 12, 2010)

Post what you have and let it fly. 
Or post just enough to get a nibble and maybe someone will you.


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## Hippie (May 12, 2011)

riverpc100 said:


> I don't know if this is appropriate for this forum but, I figured it can't hurt.
> I've posted a couple of times about the project I'm on and people in this forum have been a big help.
> So now that I'm close to the finish line with this, and it's not my normal cup of tea, I'm looking for someone
> to do a review of this design. Not sure what the fee would be but sounds like the next step for me.
> ...


Power distribution to the drives? I would use a distribution lug block after your disconnect in the cabinet and tap off that


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## Hippie (May 12, 2011)

Not the best picture, but this


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## Wirenuting (Sep 12, 2010)

From the block you can drop into small breakers kind of like this pic.
There is a 35 amp breaker feeding several smaller ones.


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## riverpc100 (Dec 2, 2012)

*the main panel*

This is the main panel, it feeds a "remote" panel that only has 1 heater and one small VFD drive running a 3rd HP blower.
Most of this was drawn, instead of using the correct symbols.
It works for me ATM


UPDATE : The drawing is posted below without any cuts


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## riverpc100 (Dec 2, 2012)

*e-stop*

Another concern is the E-Stop method I'm using.
Does it look ol ?


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## riverpc100 (Dec 2, 2012)

OK I meant


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## RonBaggett (Jan 9, 2013)

riverpc100 said:


> Another concern is the E-Stop method I'm using.
> Does it look ol ?


 Estops look OK.


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## RonBaggett (Jan 9, 2013)

riverpc100 said:


> What I have is a production line with 2 control panels, and 2 cabinets that house VFD drives
> power supplies and all the other goodies we think we need.
> No PLC, just some relay logic, contactors, SSRs and terminal blocks.
> The control panels have no electronics other than a couple of LCD readouts.
> ...


First of all, not enough information. Your CPT fuses are on the load side. See 450-3(b). And they are too large. Your main disconnect appears to be 100 amp. You would need additional protection for your downstream loads.
Your text does not agree with your diagram. Diagram indicates 6 loads. Text indicates fewer loads.


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## riverpc100 (Dec 2, 2012)

*more info*

Yes the main Disconnect breaker is 100 amps. Haven't gotten a total yet.
It's kind of a holding piece for now.

I do have breakers on all loads as far as I can see, it was cut out of the drawing I posted.

The loads are,

2 - 2600 watt heaters @ 220vac single phase
4 VDF drives 3HP maxx) runnig 1 Xs 1.5 HP 3Xs 1.0HP.
1 6000watt heater
2 control power transformers (ac/dc) less than 2.5a total
8 24VAC solenoinds > less than 500 ma each.
a few small temp / speed meters not using much DC

alot of the parts used are very over rated for their use since I don't trust
manufactures ratings anymore, and don't like to run things near rated capacity.
I have the power dist' blocks set up to add one more small VFD
I have the wiring and breakers going to the self contained heaters are 3 pole. I think he'll
be changing to 3 phase heaters for them in future.

I saw a screw up in my power on and E-Stop wiring so fixed that and will re-post with all devices on this section.


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## riverpc100 (Dec 2, 2012)

This is the whole page with nothing cut, and the E-stop circuit fixed.


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## riverpc100 (Dec 2, 2012)

*MORE on this*

Was talking to a friend about this the other day. I originally planned to use
SSRs to run all solenoids and contactor coils in order to have all low current at both operator panels.
Control panel switches usually handle 10amps and most os my load is solenoids and a couple of contactors.
Then rethinking this guy I was going to take most of them out. Less chance of failure if they're not there.
My friend says OH NO, leave them in, we always used zero switching SSRs to preserve the life of our solenoids and relays. 

Anyone doing this for his stated reasons ???

here's how it is set now, the drawing is typical use of SSRs on this line.


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## RonBaggett (Jan 9, 2013)

The concept is not restricted to solid state relays. This is called slave (isolation) relays.


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## RonBaggett (Jan 9, 2013)

The ssr relays reduce the surge caused by switching.


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## riverpc100 (Dec 2, 2012)

So are you saying they are commonly used even on low current loads for that reason, to extend equipment life?


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## RonBaggett (Jan 9, 2013)

Depends on inrush and the device rating. Do you have any history indicating life expectency? If they are made in China .... YES! My experience has mostly been with 120vac solenoids. Our main problem was the coils would high resistance short to ground. We changed style of leads (more expensive ones) and the problem went away.


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## riverpc100 (Dec 2, 2012)

Thanks, 
This new line will be worlds apart from the existing lines in use now. And will cost more to build. The guy footing the bill will question things like SSR s and reactors. If there were better maintenance records it would help to justify the extra expenses.
My main concern is safety, so everything that can be is low voltage.
The rest will be in pipe.
It's not a big undertaking by any means, just a big change in the way the line will be built.


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## JRaef (Mar 23, 2009)

Simple zero-cross SSRs will NOT reduce the coil inrush current, I don't know where you got that idea. All a zero-cross SSR does is reduce the electrical noise that happens as a result of turning on a relay by switching on only when the AC is at zero volts. As soon as the AC sine wave begins to rise, the inductive coil still has to magnetize but until it does, it is still essentially a short circuit and that is what causes the inrush. If you spend the extra money to buy a Phase Angle controlled SSR that ramps the voltage slowly over time, then the inrush can be reduced, but then you may have other problems.

Also, SSRs are not a good idea for use on inductive devices like solenoids and relay coils in the first place, without some serious need for their capabilities and an understanding of how to protect them from the negative effects of inductive loads, called "inductive kickback". It's not a big deal, but it cannot be ignored and it does add cost.

SSRs hgave two main uses: 1) high duty cycles, where you have to switch a LOT of times in a short period and / or switch very fast; 2) where electrical noise caused by switching on iof RESISTIVE elements that have a high PTC ratio will create other problems.


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## l0sts0ul (May 7, 2011)

When I was in plastics manufacturing, I used a lot of mercury connectors instead of relays because they have a ton more duty cycles and the lifespan is much longer, not to mention the high current capacity for the small footprint. 

I agree with the previous post. SSR will not reduce inrush, only a soft start will as it will ramp up as set. 

I prefer SCR for faster switching and control of higher current loads even more then merc.


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## JRaef (Mar 23, 2009)

l0sts0ul said:


> When I was in plastics manufacturing, I used a lot of mercury connectors instead of relays because they have a ton more duty cycles and the lifespan is much longer, not to mention the high current capacity for the small footprint.
> 
> I agree with the previous post. SSR will not reduce inrush, only a soft start will as it will ramp up as set.
> 
> I prefer SCR for faster switching and control of higher current loads even more then merc.


Not to mention the fact that mercury is a big no-no now. I don't thionk we can even use the WORD mercury in California any longer.


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## RonBaggett (Jan 9, 2013)

Here is a link to info on ssr relays.
http://www.idec.com/language/english/catalog/Relays/RSSSeries.pdf


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