Machine Re-Location Help

[Ace1985]

Hello,

I'm new to the forum, so sorry if I've posted this in the wrong section! I'm a mid 20's lad due to oversee some machine re-locations from Central Europe (Czech Republic) to the UK. I'm just wondering a few things.

1) If the 3 phase machine in it's current location is running at a supply of 380v, would it have a negative impact running it at 400v+ in the UK?

2) Is there any other UK/Europe discrepancies I should be keeping an eye out for? The machine uses a 3 phase supply, pneumatic and hydraulic systems.

3) I've covered alot of questions for the maintenance manager like can I see all techical manuals, is there a planned maintenance schedule, any current service contracts etc. I'm trying to cover every aspect though, so any suggestion for questions to ask would be very helpfull! (I've also asked for a critical spares list, any previous breakdowns, things like that)

Finally, one of the points brought up in the board meeting was that we're going to avoid shipping machines during Jan/Feb due to potential freezing issues. Is this a good idea? Anyone had bad experiences shipping during the freeze periods?

As I said, ANY help is appreciated because this is my first trip away with work and I don't want to miss anything out.

Thanks in advance.

 

[Ace1985]

With regards to point 1, I think (from a google search) that the UK & Czech both operate on a 400v @ 50hz 3-phase systems.

I got told in work that they 'most probably' run at 380. Can anyone confirm or deny this.

Regardless, if it was at 380v, could it impact the machine if ran at 400v?

Thanks

 

[Skogsgurra]

The forum is right. The questions are relevant. The freezing risk is real, especially if cooling water and certain cutting liquids are left in the machines.

The EU is supposed to have harminized the supply voltages. The former 380 V system has been changed to 400 V and the former 440 V system has been changed to 400 V. That also means that 220 -> 230 and 240 ->230 V.

That is the theory. The truth may be so, too. But no guarantee. If you relocate and connect to a medium voltage supply, you can have your transformer set as you wish. If you are connecting to an LV grid, you may have to look at each individual machine.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

Another possible aspect of freezing is condensed water in air systems.

Bill
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"Why not the best?"
Jimmy Carter

 

[jraef]

How long has the machine been idle? There are potential pitfalls there too, especially if it's been more than a year.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[electricpete]

Good point by Jeff (although it sounds like op may be looking at similar considerations in his #3). I have to mention we had a motor failure last week which required us to pull our spare motor out of the warehouse after 20 years storage, to install into the plant. It is a 600hp, 2-pole, horizontal sleeve bearing motor. I was asked whether it was really required to do a shop test of the motor prior to installation (bearing in mind the motor has certain regulatory/quality requirements which create mountains of paperwork which dramatically slow down any/all vendor work, and the plant need was urgent). I reviewed our storage preventive maintenace, which included checking space heaters on by current measurement, checking insulation resistance, rotating the shaft periodically. I responded that we would have reasonable confidence in that motor as long as it passed some quick on-site inspections by doing shaft lift check, TIR check, remove endcovers, support rotor and roll out the sleeve bearings for bearing inspection, check for foreign material and corrosion visible from accessible openings, megger, bridge (I would have also checked bearing clearnace and housing clearance by plastigage if lift check did not pass). I held my breath as the motor was started after installation, because I would have been a real goat if we had to turn around and yank that spare motor back out. Luckily for me it started up and hummed at 0.03 ips with cool temperatures for 2-hour uncoupled run. That's not particularly relevant to this thread, but a minor success story that's very fresh in my mind.

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(2B)+(2B)' ?

 

[rmw]

Actually Pete, I think it is becaused your anecdotal story has given him a laundry list of things to consider. Well said.

rmw

 

[MikeHalloran]

I had a bad experience, when a big rainstorm showed up on the same day as the riggers. They could not be persuaded to delay loading our precious machine tools onto their flatbed truck, not for even an hour. The tools were greased and covered, but the riggers unavoidably tore or dislodged wrappings, so the precision ground ways ended up with some brown spots on them that can never be removed.

If at all possible, use covered trucks and load and unload them under shelter, or write your contract so sunny days are required.



Mike Halloran
Pembroke Pines, FL, USA

 

[electricpete]

Thanks rmw. Probably not deserved in this case, but I'll take it ;-)

Mike's comments bring a few more random thoughts about shipping to mind - of course the shafts need to be blocked before shipping for best chance of not damaging the bearings during shipment. Also oil needs to be drained just before shipping to avoid spilling oil on the windings, then added back in shortly after receipt to avoid corrosion of the bearings.

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(2B)+(2B)' ?

 

[ScottyUK]

Check nameplate data. In this world of European harmonisation we're all nominally on a 400V 50Hz supply, but if this is older equipment then it may be plated for 380V and will likely be in trouble on the UK's supply which is toward the top end of the tolerance on the 400V nominal voltage.

Nice to see some manufacturing coming back to the UK - so much has moved to the old Eastern Bloc in recent years.


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If we learn from our mistakes I'm getting a great education!

 

[Ace1985]

Thank you VERY much for your replies! After a good couple of hours reading through here, it's nice to see such enthusiasm in replies to a forum and not your usual sarcasm that dominates most online forums!

To jraef - The machine is in production as we speak. It's literally an unplug and re-locate job. So no idle time.

To electricpete - That the type of answer I was after. Previous experiences. Thank you very much for that!

To ScottyUK - Yes, it's brilliant news that we're getting some equipment back! It seems to be a one way system over the past 10 years or so! IF the machine was designed at a 380v spec, what potential problems could we have when powering up to our strong 400v?

Again, thanks for all your replies! I'm back on site tomorrow so will probably throw up a few more questions!

 

[waross]

If the voltage limit is exceeded the motor will saturate magnetically. When the motor saturates the current will increase dramatically even unloaded. The current tends to be limited by resistance alone with little or no limiting by inductance. Hopefully the overload protection will disconnect in time to prevent burnout.
An anecdote that may be useful:
At one time I was working in an area where the utility changed their standard industrial voltage from 480V to 600V. We had a plant with a combination of new 600V motors, 480V motors from the old plant and from time to time, 600V motors from a sister plant.
The main service was a unit containing service entrance and metering, a 600V MCC, a section with an open delta auto-transformer dropping the 600V to 480V and a 480V MCC. We would be called from time to time to change out equipment for one reason or another. Often the feed to the equipment location was the wrong voltage and another set of dry type transformers would be added to re-correct the voltage.
You may consider an open delta auto-transformer installation for either the whole plant or, if most of the motors operate successfully, just for problem motors.

Bill
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"Why not the best?"
Jimmy Carter

 

[ScottyUK]

The biggest problem will be over-fluxing of the iron on motors and transformers, plus any electronics fed from the transformers may not be happy at 10% above nominal rating. It may manifest itself as everything running a bit hot, or as premature failures, or it may just be ok.

Measure the local supply voltage. Some places in the UK it is just over 400V, other places it is closer to 440V. An auto-transformer isn't all that expensive if you need to drop the voltage a bit.


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If we learn from our mistakes I'm getting a great education!

 

[waross]

There are two basic circuits. Wye connected auto-transformers and open delta connected auto-transformers.
Wye connected needs three transformers and a fourth, neutral conductor.
Open delta needs two slightly larger transformers and does not require a neutral connection. The open delta auto-transformer may be used on a wye system for three phase loads such as motors which do not need a neutral. The open delta leaves one phase at 277V to ground as a 480V wye system and the other two phases are a little more than 347V to ground. 347V is the normal voltage to ground on a 600 Volt system.

Bill
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"Why not the best?"
Jimmy Carter

 

[ScottyUK]

FWIW I have never seen an open delta connection used for a power circuit over here. Our regulations require a solidly earthed neutral on LV power installations. Open deltas occasionally turn up in archaic metering / relaying circuits, while the similarly-named broken delta is not uncommon in older installations.


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If we learn from our mistakes I'm getting a great education!

 

[waross]

Hi Scotty.
The open delta boost does maintain the solid neutral if one is present. It does shift the neutral a little. The primary current is a little higher on one phase. Ground fault currents on two phases may will be limited by the impedance of the auto-transformer
I have used it many times without incident. If several open delta boosts are used on a gen set, best practice is to "roll" the connections to balance the slightly unequal currents.
The other option is the three transformer wye auto-transformer circuit. This circuit should have a neutral. With an equipment grounding conductor this brings the conductor count to five. I have seen issues with temporary power where the plug connected power cables had only four conductors and the equipment grounding conductor was used as the neutral conductor also.
We had a 30 Amp circuit inadvertently energized with the ends of the wires shorted. As well as taking out the 30 Amp breaker the main feeder breaker also tripped on ground fault. This left the entire work area in the dark during a 24/7 turnaround. The site was down for four hours until the cause of the outage was determined and it was deemed safe to re-energize.
The cause may have been poor coordination but I believe that the connection between the auto-transformer neutral and the equipment ground may have contributed to the tripping of the upstream breaker. With the open delta boost, there is no connection to neutral, even though there may be a neutral in the system.


Bill
--------------------
"Why not the best?"
Jimmy Carter