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[shagg]

Hi Guys

I've been asked by an engineer to wire a machine he's working on. and this isn't normally my area, but i don't really want to pass the job up.

The machine is a test rig with a slider arm driven by a rotation of a 3 phase motor (.18kw). Now the slider has to slide a 1000 time then stop.
the motor will requirer an emergancy stop as normal.

So my question to you guys in the know is how you would go about wiring it and the components needed

 

[Darkwood]

Its nice to be keen to learn here but this is an area that you really need experience in, you are working outside the scope of the BS7671 and will be clueless as the the regulations you are required to comply to...

A risky assesment of the machine is needed to see what safety category it needs to comply to if any at all.


The actual wiring and function may be simple for the control but a control system may need design criteria like fail safe or redundency to either or both protect the machine from damage and the user.

You have give us very little to work on but at a stab in the dark you probably require a pulse counter watching a proximity sensor but many variables and options exist that may be better suited to the machine set-up.

Be careful before taking this step and you may be best getting someone in experienced in this area and possibly working together on it which
A- Gets the job done correctly
B- Gives you an insight to exactly what a mine field you could be stepping in.

Just imagine someone is injured by the machine ...the first port of call will be the guy who designed the control system.

 

[shagg]

Thank you Darkwood for your reply. I've already contacted the guy and pass him a local panel builders contact details. I felt I was out of my depth a little lol. It's a shame because it ready interests me. but safer this way all round.

 

[Darkwood]

As you are employing the panel builder you can ask if he minds just giving you a run through of the set-up once installed im sure he'll be able to spare 5mins tell him your interests and as how to move into that field, but wise to outsource a panel builder ... browse the control diagrams when its fitted have the task is been able to read and follow them and you would be required to provide one yourself so another area you need to swat up on.

 

[shagg]

I'm not employing a panel builder I've gave the engineer a panel builders number. but I see where your coming from, it would be nice to see how it's done, but I don't think they will let a potential competiter in to see how it's done.

 

[Darkwood]

I get the picture.... yes agree its an interesting area to get into, im doing a panel for a cutting machine in a bedding firm that is self controlling but runs at the end of a carding line, im only controling 3 small motors but requires a plc with 20+ outputs and a whole wealth of sensors and monitors.. just how much actually goes into making 3 motors work in sequence at the correct time and speed can be mind boggling to those not experienced in panel building, the safety system can sometimes take up a majority of the cost.

 

[gnuuser]

[SUB][SUP]

Its nice to be keen to learn here but this is an area that you really need experience in, you are working outside the scope of the BS7671 and will be clueless as the the regulations you are required to comply to...

A risky assesment of the machine is needed to see what safety category it needs to comply to if any at all.


The actual wiring and function may be simple for the control but a control system may need design criteria like fail safe or redundency to either or both protect the machine from damage and the user.

You have give us very little to work on but at a stab in the dark you probably require a pulse counter watching a proximity sensor but many variables and options exist that may be better suited to the machine set-up.

Be careful before taking this step and you may be best getting someone in experienced in this area and possibly working together on it which
A- Gets the job done correctly
B- Gives you an insight to exactly what a mine field you could be stepping in.

Just imagine someone is injured by the machine ...the first port of call will be the guy who designed the control system.

darkwood is correct.
in a system such as what you are describing you would have to have a brake motor
we use sew brake motors in the auto palletizers and they are trouble free under most conditions.

@shagg
i dont want to dissuade you ! on the contrary I want to encourage you to get the education as a panel builder and industrial spark.
qualified industrial sparks are needed everywhere.
seek the education for it and employ the use of a panel builder who will allow you to assist.
see the project from all safety angles for anything that could possibly go wrong and design the system with that in mind.
but do not attempt this without the proper education and qualifications!
( im an industrial spark here in the US. ) [/SUP][/SUB]

 

[Knobhead]

A braked motor is far from trouble free. With you working on auto-palletizers I find the statement hard to believe. GEC were a pain in the arse, SEW faired better. You have to know how to set the braking up to get the best out of them.

 

[High Tower]

Thank you Darkwood for your reply. I've already contacted the guy and pass him a local panel builders contact details. I felt I was out of my depth a little lol. It's a shame because it ready interests me. but safer this way all round.

Noble call!!, however take the day off and ask the panel builder if you can be present when it gets fitted. Worth it to learn new skills!

 

[gnuuser]

tony thats why i stated under most conditions meaning they must be set up properly and correctly maintained.
if they aren't then they can indeed be a problem device.
weve also tried gec and our purchasing department went to sew drives.

currently we are replacing the euro drives in most of the conveyor systems with the varimot drives.
i would prefer top of the line motors for our equipment but i'm not the purchasing office for our factory.

still regardless of the equipment anyone installing it needs to be thoroughly familiar with they are working with.

 

[Knobhead]

The biggest problem I've had with braked motors has been a total lack of understanding of the working conditions of the motor by the machine manufacturer. I spent quite some time at SEW's factory just learning how the braking systems worked, then I had to correct all the design flaws in our palletizers.

 

[gnuuser]

The biggest problem I've had with braked motors has been a total lack of understanding of the working conditions of the motor by the machine manufacturer. I spent quite some time at SEW's factory just learning how the braking systems worked, then I had to correct all the design flaws in our palletizers.

right on the money there
we were sent to off site schools for training on them. and each of us was given complete manuals and specs on the brake motors.
so i know what you mean about them.
it was a bit of a puzzle to get the timing just right in the plc's and the parameters correct in the vfd's
(nearly pulled all my hair out and as i am bald thats a neat trick for me)

 

[Knobhead]

Could be worse though. Ever used "plug" braking? Quite funny at first when a 60HP motor shaft shears. Not so funny when you're changing it!

 

[gnuuser]

Could be worse though. Ever used "plug" braking? Quite funny at first when a 60HP motor shaft shears. Not so funny when you're changing it!

seen it in some older electric forklifts (those motors could handle it) but also saw one of the guys try it on a guaging machine (smoke and stink and a trashed gear box as he was running it at full speed) the boss had a fit about it

 

[SheffSimon]

right on the money there
we were sent to off site schools for training on them. and each of us was given complete manuals and specs on the brake motors.
so i know what you mean about them.
it was a bit of a puzzle to get the timing just right in the plc's and the parameters correct in the vfd's
(nearly pulled all my hair out and as i am bald thats a neat trick for me)

Always best to get the VFD to control the brake contactor, rather than the PLC...otherwise you can end up dropping the load (or your palletiser hoist) or the VFD is still ramping down when the brake is already on....neither's good

Commissioned many many palletisers in food and bev plants...I used to quite enjoy em.