European motor wiring 4

[gcforest]

We have three new pumps with single phase 230V Italian (Lowara) motors. The only three terminals for wiring are "L", "N" and ground. I guess the "L" is meant for a 230V single line (as it is in Italy)and the "N" for neutral. Is there any way to wire this to our two wire 230V supply? Our vendor told us to run 115V lines to "L" and "N", and neutral to ground. That doesn't sound right. Can anyone offer advice? Thanks!

 

[Skogsgurra]

The L and N should be isolated from ground (check!). So you are free to connect L to one of your phases and N to the other one to get 230 between L and N. No problems at all if it is a 230 V motor. And ground to ground if you want to avoid "ashes to ashes".

Gunnar Englund

http://www.gke.org

 

[davidbeach]

To add to what skogsgurra said, the pump will also run 6/5 normal speed. Depending where on the pump curve you are operating, that might be enough to overload the motor.

 

[waross]

We are assuming that this is a 50 hz. motor (Italian, marked 230V, L & N) and that you are are on 60 hz.(115/230V).
If so, your motor will also rerate to 276 volts. Even at 276 volts, davidbeach's post is true. At 230 volts the chances of overloading are even worse.
If, however, the motor has been designed for 60hz. for export, it should work fine.
If it is a 50hz. motor, (it will say on the nameplate)check the current when you put it in service. If the current is less then the rated current, you have no problem. If the current is more than the rated current try to borrow a transformer or auto transformer and boost the voltage up to 276V more or less.
If the pump is overloading, there is still something you can do.
On a centrifugal pump you may reduce the load by throttling the pump discharge.
respectfully

 

[Skogsgurra]

It is a pleasure to "work" with you two guys! Catching the important details and turning a hasty remark into a full answer. Love that.



Gunnar Englund

http://www.gke.org

 

[mc5w]

I worked on a paperboard box corrugator line that had Italian 3-phase motors that were designed to run on 60 cycle U.S. juice. The only thing wrong was that a blower motor for sucking up sawdust ran chronically and slightly overloaded in our application and it did not help any to frequently clean out the vacuum filters. Italian motors have zero tolerance for deliberate overloading, this is, they refuse to build service factor rated motors.

This line also had some Italian direct current motors which use square frames instead of the round frames that Baldor uses.

Your Italian single phase motor probably is rated 50 Hertz but under U.S. rules you need to rename L and N as L1 and L2 if connecting to 120/240 single phase or to a 240 delta system. If your 240 volts is derived from 277 volts from a buck-boost transformer then leave the labeling as is and connect N to the neutral wire that comes out of the buck-boost transformer.

Germany also makes 60 cycle motors for export to North America, Australia, and some South American countries. At a factory where I worked I had to convert a German machine from 240 volts corner grounded to 277Y480 volt operation. The 2 lubrcation pumps were 9-lead 240x480 U.S. dual voltage and the two 10 HP motors were 240 delta by 416 wye 6 lead. I had to install 3 1 KVA 240 volt by 32 volt buck boost transformers to get 240Y416 volts.

Mike Cole, mc5w at earthlink dot net

 

[gcforest]

Thanks for all the info. You guys are great!

The pumps are hooked up and running, but the motors run hot; the thermal overloads trip occasionally (and automatically reset after a few minutes). They are rated at 230V, 60hz, single phase. Our voltage averages 245. Is that a factor in running hot? Or perhaps the motors are undersized for their job?

 

[waross]

245V is within the normal 10% limit in NEMA land. Normally a motor would be expected to run a little cooler at higher voltages within the 10% tolerance.
What type of pumps are these?
If they are centrifugal pumps I would (and have many times) restrict the discharge of the pump until the current drops a few percent.
You may want to borrow a 240V/12V transformer and use either an autotransformer connection or a buck connection to drop the voltage 5%. If the motor current drops and the motor runs cooler, it is an indication that the 245V is too high.
respectfully
ps. Thanks for the comments Gunnar. It means a lot coming from someone of your knowlege and experience. I am also honored to be included with someone with the expertise of davidbeach.
wr

 

[stardelta]

The fact the thermal keeps tripping indicates that the winding is getting too hot, its there as a safety feature to protect the winding and if ignored, in time the winding will fail. I dont see the 15v difference as an issue, 1ph supplies over here can differ by just as much if not more, and the difference in current as a result wont be enough to cause serious overheating. I cant see any confirmation of the supply frequency but am assuming its correct for the motor at 60hz. My thoughts are that the motor is being overloaded. As its a 1ph unit Its not going to be a realtively large pump and as such will have little if any spare capacity. You need to check the full load running current and compare it to the nameplate, if its way over it indicates the pump is undersized. It may also be a good idea to post the question in the pump and fluid engineering forums. Pumps as a rule have to be matched to the application and the design of the piping system.