A proper estop circuit

I am trying to combine an auger filler with a packing machine. Neither of the 2 machines have a proper safety circuit.
The power feed in is 230volt. I have a automationdirect VFD that drives a main motor. A contractor and motor that dirves the auger and a new micro830 PLC that I set up to receive a signal from the packing machine to release the auger brake.
Im not very experience with this type of work but I have the machines working together. Now I would like to finish up the machine by installing all components into the panel & create the safety stops.
I would install an Estop switch, main power switch & switch for the auger.

Im having a really hard time figuring out what I would use to power the coils on the estop relay. I have the 230 volt hots, but no neutral. I also have the 24v from the VFD. I would assume I use the 24v, but the schematic I look at for the estop relays show a line voltage including a neutral.
Any guidance would be appreciated.

Hello Jwalter!

I would go with a safety relay. This will make things pretty simple for you and will be a very safe method. I would go with a Pilz or an Allen Bradley (SIPHA)style Emergency Stop Relay.

You can power the relay with the 24VDC you have.

The idea behind the e-stop relay is that your E-Stop loop is voltage free. So is your reset loop. You can run through every component of your production line to built your loop.

Make sure you use the safety contacts for your safety permissives and the signaling contact for your signaling purposes. If you need more contacts than what's available, I sugest you use a Pilz extension module or you could also use OMRON positivly driven contact relays, which provide an added safety feauture over normal relays.

I hope this helps!

Hi

First you need to work out the rating your system should be before you design your system. This is done with a risk assessment and this also creates some of the paper work that is required.
Working and wiring Safety circuits has become much easier from a wiring point of view but the paper work has gone up many fold.
Be carefully taking on a safety project like this as it falls back on you if something goes wrong ( hopefully not)

Donnchadh

jwalter007,

you mention in your post e-stops and also safety stops.
e-stops kills the machine while a safety stop brings the machine to a halt in a specific manner.

look at nfpa79 - electrical machinery.

i may have this wrong so you will have to confirm this.
what i would suggest is look at each piece of equipment and see what power is available.
then choose an e-stop relay. we use banner.
take each piece of equipment and interface that to a relay (you will need 2 with suppressors - rly 1 & rly 2 for each piece of equipment). series rly 1 contacts into channel 1 of the e-stop circuit and rly 2 contacts go into channel 2.
the e-stop relay will power a power contactor which in turn powers each piece of equipment. you will also have an input going to the plc to tell the system power is applied.

this is a dual channel system in case one of the relays sticks.

you could use a n.c. contact from rly 1 for 1 pare of the safety rly and a n.o. contact from rly 1 for the other part of the circuit.

its been a while since i've done this, so you will have to verify what i said and conform to osha and nfpa 79 rules.

regards,
james

I would follow 'Donnchadh' you need to assess the safety requirement properly.
since you are inexperienced I would search this site as there are other safety related posts.
OR
have a consultant give you a written report.
It is easier to help you with that info

Thanks everyone, for the input.
I want to point out that I am building this machine for myself, for personal use.
The product that Im making is more of a hobby than anything else.
I do still want the machine to be safe and I want to build it right the first time.

I will continue researching the points that were brought up here.
I would love to have a someone hand draw me a wiring diagram. If anyone would like to do that for me I would appreciate it.
In order to have no liability, I would not require a name on the drawing & I would be happy make a donation to a charity of your choice in your name.

thanks again.

Hi Jwalter,

Allen Bradley do a booklet named safebook 4 which can be downloaded free from http://www.emea.rockwellautomation.c...ety_guide.aspx
Please be aware that this booklet is intended for European standard EN 13849-1 but the concepts of the safety terms will be the same. It will give you a good insight into the requirements of the risk assessment which is the initial step to designing the safety circuit.
Also Pilz have a manual that shows working examples/ drawings using their safety devices to incorporate estops/ door switches, etc. It can be downloaded at
www.galco.com/techdoc/pilz/pnoz_x_app.pdf
Hopefully these documents will give you a good insight into the requirements of safety circuits and how to design/ wire them.

Regards,
Donnacha

Hi Jwalter,
In your original post you mention taking 24VDC from the VFD to power your proposed safety circuits. Please check the current draw as small VFD's have very limited power available. you may need to consider a 240v to 24vdc supply and use a double pole mcb to protect it (you will be using two live feeds).
Paul

Seeing you're in the US and you're using 230 and this is a home project, I assume you're pulling an L1 and L2 off your 230V breaker panel. Why not just run a third wire from your panel box for the Neutral so you have both 230 and 115? Then you can use any number of standard e-stop relays. Again, risk assessment would indicate which safety class you want, but it could be as simple as a single 120V e-stop relay through an e-stop PB. Use the contacts on the relay to break your motor contactor and the enable to the VFD. If you want to be more safe, install an additional contactor before the VFD and kill that, removing all 230 from the drive. Safer than that, is redundant e-stop relays, in case the contacts on one weld. Safer than that is a safety relay with dual channel and checkback circuitry to detect no motion before reset. For a home project, I'd go with a couple of redundant e-stop relays and call it a day.

Im actually setting this up in my warehouse area of my commercial building. It has 220 run and the breakers arent close by.
Im going to read up on those pdfs that were mentioned above.
If anyone wants to sketch me a schematic my donation to charity offer stands. thanks

since your breakers aren't close by, you will need a disconnect at each machine.

NEC 70 main disconnects must be within sight of the operator at all times. line of sight means within 50 ft.
if you are working on the back of the machine and cannot see the breaker, you must use a disconnect and use loto.

regards,
james