different voltage systems

[astroid]

Our Paper plant uses 380 V for LV distribution. We have recently purchased a second hand Paper Mill from Australia where Power distribution was 11 KV, 3.3KV and 415 V. The total plant load was 15 MW. In all 30 Transformers 11KV/415V and 1000 motors will be installed in this Plant. Changing to 380V will delay the project and escalate cost due to re-engineering, apart from many equipment from old plant possibly not be used. What are the possible issues if we retain 415 V system and equipment. Relocated Plant will be erected in same premise as existing.

 

[krisys]

Transformers having 415V secondary is presumably having off circuit tap changers with +/-2.5% and +/-5.0% tap positions. Play around these tap positions to optimise the bus voltage. As such the equipment have voltage tolerance. The tolerance could be either +/-5% of +/-10% depending on the specification of the equipments.

You should be able to run the motors, with some optimisations applied.

 

[ScottyUK]

The transformer will frequently be specified with a nominal voltage slightly higher than the system nominal voltage, for example a 415V system will likely be fed from a 433V or 440V transformer to allow for volt-drop in the cables. My understanding is that the US does this slightly differently by using 460V motors on a 480V system, but achieves the same thing.

 

[waross]

I would hope that the purchase included the distribution transformers.
You have told us that your utilization voltage is 380 Volts but you haven't told us your distribution voltage.
My first reaction would be to investigate the feasibility of providing 11 kV to the mill and using all the transformers from the purchased plant.

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

 

[astroid]

You are quite right Waross, the Purchase includes all Transformers (used + spare) complete with HT/LT Switch-gear, Protection etc. Our existing system is 70KV from State Utility, 20KV / 11KV / 3.3KV and 380V. Gen-1 is 11MW / 3.3KV and Gen-2 is 38MW / 11KV. We intend to add a new Feeder from State Utility and use a 70KV/11KV Transformer to feed the new Plant. Then use purchased equipment as far as possible. As the new Plant has no Captive Generation, we are concerned about the system stability and the risk of a Tie, especially on the LV side might result in.It is a possibility / risk we must consider now.

 

[Skogsgurra]

The numbers, are they nominal voltages or actual ones?

Europe (if that is where you are located) has "harmonized" the three-phase voltage to be 400 V (instead of former 380 V) and Australia did the same thing. Some countries in Europe and territories in Australia "harmonized" obediently and others did not. So, there are several possibilities of which some are good while some are not so good.

If the Equipment has arrived at your site, it is a good idea to spend a week or so to study the nameplates and the tap changers to find out what the options are. It may even be worth a trip to down under.

Gunnar Englund

http://www.gke.org

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

 

[waross]

Good points on harmonization and actual versus nominal voltages Skogsgurra. However couple of points for consideration,;
" We have recently purchased a second hand Paper Mill"; Possibly pre-harmonization.
"the Purchase includes all Transformers (used + spare) complete with HT/LT Switch-gear," It may be a safe assumption that the transformers and motors have been working and playing together well for some time now.
However your comments are very insightful when considered in relation to the 11 kV supply.
In support of Skogsgurra's comments it may be extremely important to ensure that the actual supplied voltage at the new site matches the actual applied voltage at the old site. An advantage of a trip to site is the possibility of locating someone from the plant electrical department or the engineering department for first hand information as to any voltage supply issues that may be corrected during the re-assembly.


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