What are you doing as trainees?

[Poult12]

As it stands im a service engineer for a fire alarm company. Although supposedly trying to complete my level 3 nvq 2357.

Although my collarbone decided enough was enough and collasped...

 

[ElectroChem]

Well, this thread derailed quickly. :biggrin:

I'll make an attempt to get back on track. Our company does mostly industrial maintenance and installation, so my work can range from running lighting circuits through false ceilings to control panel works and motor troubleshooting. We have one major client which is a poultry company, so we follow their whole workflow from hatchery to barns to processing plant.

Gives me a great range of experience that will stand me in good stead later. Today I was wiring shielded 4-pair analogue into a PLC card, tomorrow I'll be soldering a control cable for a palletising robot, TAFE (college) Thursday and who knows after that!

 

[Bobster]

So the consensus so far is only one in here (not including MDJ), has hands on work regarding motor control.

The challenge I normally set is drawing up some different methods of starting, If people want me to put a little something together shout up. I don't want to set something that the majority will have no idea where to start, as this becomes off putting and I find people won't try and attempt it.

 

[happysteve]

Hi

I'd like to learn more about motor control. I don't think it would be off-putting - I think it's good when mentors (or even other trainees!) set problems whereby the answer is bigger than perhaps one trainee can solve on their own. Some of the best threads I've seen in here (the trainee section) are where there's an active discussion amongst the trainees about what's going on, with occasional prods by interested mentors, and a final "reveal" at the end of the "ideal" answer if we never get there. It's a bit like the blind leading the blind, but it shows what our thought processes are and where we're coming from.

The closer it is to real life problems the better

Thanks for offering to do stuff, it's appreciated.

 

[Bobster]

Ok then, something simple to start with. A DOL starter. Just a simple start/stop with an overload connection. For the purpose of this there will be no E-Stop required.

I'd like a schematic drawing of the following circuit.

Motor rating for simplicity, 1.1Kw 3phase, ignoring power factor and efficiency.

Supply to the panel will be 3Ph+N. 400v 50Hz.

The control voltage for this will be 24VDC, that will have to be sourced from the 3ph supply via a PSU.

If this doesn't work out too complex for people, I can start adding to this as a base point.

I'll even start you off with the power side of this drawing.

You will however be required to add the rating of the overload. (Can't do anything without a little maths.)

 

[happysteve]

Alright. Anyone want to have a crack at this?

 

[pennychew]

I can't zoom in on the laptop for some reason, I've downloaded the file then opened it but you can't read the symbols when you zoom in. Might be an apple mac compatibility issue?

 

[happysteve]

I'm struggling a bit myself, to be honest!

 

[ElectroChem]

In order from top to bottom you have:
L1 L2 Ĺ3 N E
Main Panel Isolator Q1
Main Contactor K1
Motor Overload (can't make out the symbol I'll be using TOL as that's what I've been taught)
Local Isolator Q2
Motor

As a basic motor control is fairly simple for me I'll PM my answer tonight unless you'd rather I just post it up?

 

[pennychew]

Fire away mate, I think I have it done in my head but I'm watching the champions league game on the comp so I won't get it drawn tonight

 

[pennychew]

I haven't though about the overload calc yet though

 

[Bobster]

I'll blow the picture up tomorrow.

If anyone wants to PM me answers/questions doesn't matter how stupid, I won't bite.

I realise is ethos probably isn't covered much in general learning, once we get a little more in depth I'll set some of the other mentors challenges.

 

[ElectroChem]

Ok here's my go.

 

[Bobster]

Well done ElectroChem, your missing something to do with the PSU, I'll let you have a think before I let you know.

It's common practice, to have the overload contact first, then the stop button before the latching start contact.

You overload setting is correct, albeit for a 1KW instead of a 1.1KW.

Did other people manage this/understand how it's been done now it's posted up?

 

[pennychew]

Well done ElectroChem, your missing something to do with the PSU, I'll let you have a think before I let you know.

It's common practice, to have the overload contact first, then the stop button before the latching start contact.

You overload setting is correct, albeit for a 1KW instead of a 1.1KW.

Did other people manage this/understand how it's been done now it's posted up?

Yeah im ok with that, I take it the latching contact at k1.4 provides No volt release?

I cant see whats missing at the PSU either, a fuse maybe?