Star Delta starters and timers....

[Tiny Spark]

Hey all, Been away for a while with the new job thats keeping me busy!
But ive had a head banger of a day and could do with a helping hand of someone more in the know that I.

So heres the problem, We have a AHU with a large supply motor thats started via a star delta starter, Now last week 2 of the other guys were looking at this thing as it was not working and determined that there was a huge amount of things wrong!

Cutting a long list short motor was U/S, Contactors welded, Overloads cream crackered and timers shot.

So anyways they ordered all the parts and started the change over which they got half way through with, Now they both went on holiday Friday and now Ive been tasked with trying to finish it.

So I have changed the rest of the components allthough I am not 100% convinced everything is right! Obviously I didnt remove the old stuff and there is no drawings or anything to compare it to.

So I decided to test it without the 3 phase supply to the motors, Now I press the start switch, The main contactor energises along with the Star contactor but thats it, it never changes over to the Delta.

Now I think the timer is part of the problem here as when it energises along with the contactors it does not seem to time out and change state, But what concerns me is that it "ticks" instead!
Basicly it sounds like its continuously energiseing and de-energising the coil and the little amber light in the bottom left is flashing along with it.
Also when I adjust the time dial on the front it either speed up or slows down!

Now the other thing I am unsure about is the old timer had some initial on the Side (Pictures bellow) RCU.K and the New one has some other letters but they dont relate. I have no idea what these things mean so is it part of the problem?
Sorry if this is a daft Q but I dont have much dealing with these things!

Cheers

Old Timer:
http://i676.photobucket.com/albums/...8-3BE8-4778-AD37-3E1FC3B37CF6_zpsgs6i84kc.jpg

New Timer:
http://i676.photobucket.com/albums/...1-CC68-4450-B721-33213F98C74D_zpsugicsjfv.jpg
http://i676.photobucket.com/albums/...4-1ADE-4219-B239-1F72D4358AD3_zpsaruxuoux.jpg

 

[Darkwood]

Leave the star-delta starter alone if you are unsure about the concept and control wiring of these units you can do a lot of damage, if you are confident you are up to the task if you had a wiring plan then you can access them easily with google search on images or our resident Tony may give you one of his super duper animated wiring diagrams.

Trying to operate this set-up without and underlying knowledge could damage the motor and or the controls so its best to be up front and honest and say your not too sure or you could be worse off explaining why the motor is burnt out.

The new Timer will come with instructions so you need to follow them forget the old Timer the only thing thats required is the new one does the same function, this is why you need an understanding of what you are doing - a wrong connection or incorrect setting again can be costly ..the connections and their functions are clearly shown on the side of the old and new albeit using different tag symbols - they are not difficult to follow even without referring to the supplied instructions so Im a little confused exactly what you are asking here.

Lastly congrats with the new job and it seems your entering a new field so hopefully the 2 Electricians your work with will supervise you to understanding this area ... my advice is be careful here, a little confused as to why they didn't buy a prewired set up, all it needed was supply and motor connections and also surprised they couldn't put an extra half hour to the task of wiring it up before the peed off on their Jollies.

 

[Tiny Spark]

Hi Dark wood.

As I said in my OP this was just left to me as a mess of cable and parts, I have no idea of the original problems or even if it was wired right to start with as it has been somewhat cannibalised!

I have not even attempted to turn on the breakers for the motors yet as I need to get the control circuit sorted first.
I am comfortable with the way the motor windings are wired (in my comfort zone there lol)
But the controls are another matter entirely.
Its like no star delta Ive seen before.
Its done using 3 individual contactors rather than 1 unit and a mech interlock between the star and delta.

Also thrown into the mix is several relays and timers.
I cant really do much harm to the controls as its 24V AC but I am quite open to admit without a drawing ime a bit helpless as to how the hell its all meant to work!

Ide take a photo but its a rats nest of cable and you would probably cry with despair lol

 

[Tiny Spark]

Oh and just to clarify Ime looking to any potential causes as to why the timer would be "ticking" I dont know what the UER or UWR markings mean and like I said I never got left the instructions so I was wondering if it had any bearing as to the RCU.K from the old one.

 

[Marvo]

Don't know where they dug up that timer, I thought Tele had phased them out. Here's the pdf instructions. It's not a great copy but the better copy I have on file is in Germen. Depending on the actual fan I'd suggest you set it up as a single shot leading edge output with a time range of 10 seconds and the adjustment around .6 where the timer is wired to hold star configuration on the normally open.

 

[Tiny Spark]

Thanks for that Marvo, And I have no idea where it came from was just in the box with the new Schneider Contactors and O/L's LOL

 

[Marvo]

There's nothing wrong with them, we've used them many times and they've been very reliable. They were just phased out a while ago and replaced by the newer 'Enyo' range.

 

[Tiny Spark]

Any ideas as to what may cause it to tick Marvo?

 

[Marvo]

I hazard a guess it's incorrectly wired and getting it's supply via its own switch contacts causing it to cycle every time it reaches the end of the delay-on period.....but that's only a guess.

 

[Tiny Spark]

Cheers Marvo, Your educated guesses are just as good as to anything else I have to go on at this moment in time!
Think ive been chucked in the deep end here with no vest LOL
On the plus side It has not worked at all for a unknown period of time, At least now it half works so thats progress right?

 

[Marvo]

I think you're doing the right thing with commissioning the controls without the motor supply connected and I assume they've instructed you to do so because you should be at the level of experience where you can but if you feel you're out of your depth then I wouldn't be afraid to bounce it back to the guys who installed it if I were you. There's lots can go wrong with motor controls and it's invariably an expensive learning curve.

 

[Darkwood]

Sorry Tiny missed your response but seems Marvo's been guiding you so not much to add heres a link to a control schematic of various motor starter arrangements, your control voltage may differ but its a good easy to follow diagram.
Contactors and Control Circuits

 

[Tiny Spark]

Thanks Marvo.
I will get to the bottom of it one way or another.
Sadly control is not my strong point and its a vast area but without a drawing of how it should of been all i can do is make educated guesses and follow lengths of spaghetti!!
Sadly i think its one of those panels that has been mod'd and butchered countless times over the years and nobody really knows whats going on with it.
Only that it used to work and when somebody noticed it wasn't they found it to be in a very poor state and had to retrofit most of the system!!

 

[Tiny Spark]

Thanks Dark Wood great link,
Ile save that for future use!!

 

[Darkwood]

Be cautious if this is not a stand alone Star/Delta starter the control config'if its part of a larger system is unlimited and control system knowledge would be a must as well as the operating principles of unit... If its not stand alone and has been butchered like you say then I assume even I would take a while to get my head around it and I design, fault and upgrade control systems for a living.

 

[PEG]

Also,if you are not confident with the three separate contactors,be careful,not having the motor connected will NOT prevent damage,if the wrong two go in at once...what Darkwood said about understanding the specific control system,would prevent an error of this type. :stooge_curly:

 

[Tiny Spark]

Cheers guys, yes ime doing my best to fathom this one but its not been made easy.
Its over 20 years old and has no drawings etc.
I suspect there are fire relays and other such things in circuit as well.
I just found another scorched relay so just taking things a step at a time and hoping the guy on holiday will have some ideas when he gets back!!

 

[Guest111]

Ah the good old star delta,I remember going to one job and the original spark had royaly cocked it up,it was fine in start but when it went to run there was a hell of a bang and it blew the fuses.He tried it several times before admitting he'd not got a clue. lol

 

[Darkwood]

Cheers guys, yes ime doing my best to fathom this one but its not been made easy.
Its over 20 years old and has no drawings etc.
I suspect there are fire relays and other such things in circuit as well.
I just found another scorched relay so just taking things a step at a time and hoping the guy on holiday will have some ideas when he gets back!!

If as you say this is linked to the Fire system then this would up the anti- about attempting this as it has a essential safety system latched into it - this is where I would say leave it alone, before I was interested to see if you could figure it but with the extra info supplied Im a little concerned that if you do get it working and you have an actual fire then the system may not operate correctly and may aid the spread off the fire or smoke with major consequences - If yourself your colleagues are unsure as to how the system should act in a fire condition then you need to get in a Fire safety team to asses what the system needs to do to give the best chance of an evacuation of all the workforce.

 

[Knobhead]

Tiny, see the PM I've sent.