415/240V Utility Service & 240V L-N Motors

[Mchapman]

Hi All,
I am designing a small server farm that is being fed by the local utilities with (2) 2500KVA 415/240V 3PH 4W transformers. This is being done so that the servers can utilize 240V L-N at the PDU outlets. The customer would like to use multiple 1/2hp exhaust fans to exhaust the hot air & bring in fresh air. These motors are rated 115V/208-230V 1PH. My question is can I hook up these motors 240V L-N using the 230V wiring leads? Do the motor windings care if the potential difference is coming from 2 hot conductors ie: 240V L-L or 240V L-N?

 

[charlie b]

Yes you can and no they don't. But if you are describing yourself as a "estimator," I am curious to know what your role is in this project.

 

[Mchapman]

Thank you for your response. We are a small E.C. & do primarily design/build projects. So I am a designer, estimator, project manager.

 

[petersonra]

the motor windings don't care. running the fans L-N means you only need a one pole breaker and/or contactor for the fans which could be a significant simplification.

I am not sure what advantage there is to having 240 V L-N over 240 V L-L at the PDUs but there is no reason you can't do it that way.

 

[broadgage]

Should be fine.
USA type motors intended for 240 volt circuits are by convention called "230 volt" A single phase electric motor only requires the correct voltage between conductors it does not "know" if one wire is a grounded neutral or not.

Do check that the frequency is correct for the motors. If this facility is in the USA with a 60 cycle supply, though at a non standard voltage , then USA type 230 volt 60 cycle motors will be fine. If however the facility is in Europe or some other place with a 50 cycle supply, then any 60 cycle motors will be liable to premature failure, and you will need to obtain 240 volt single phase 50 cycle motors.
Most IT equipment is fine on 50 cycles or 60 cycles, but it would be well to confirm this.

 

[winnie]

If it isn't fine, then there was something almost broken in the first place.

The motor insulation will be stressed in a slightly different fashion when connected L-N rather than L-L. Since the magnet wire used to make the motor is rated for 600V, this stress difference should not make a practical difference.

-Jon

 

[ron]

Hi All,
I am designing a small server farm that is being fed by the local utilities with (2) 2500KVA 415/240V 3PH 4W transformers.

415/240V for a datacenter is not unusual. What IS unusual is that the utility would provide the secondary voltage at 415/240V.
Every data center that I do at 415/240V, I get a 480/277V utility service, and split off the HVAC feeders and feeders for the UPS / IT equipment and only step down the IT feeders after the nominal 480V UPS.
With a 415/240V utility service, your choices of native 415/240V UPSs with a UL listing will be slim (guessing you will have a UPS and this is a US installation). You will likely have to step up and back down at the input / output of a typical 480V UPS if you are being serviced by 415/240V from the utility, and affect the efficiency.

 

[mbrooke]

Hi All,
I am designing a small server farm that is being fed by the local utilities with (2) 2500KVA 415/240V 3PH 4W transformers. This is being done so that the servers can utilize 240V L-N at the PDU outlets. The customer would like to use multiple 1/2hp exhaust fans to exhaust the hot air & bring in fresh air. These motors are rated 115V/208-230V 1PH. My question is can I hook up these motors 240V L-N using the 230V wiring leads? Do the motor windings care if the potential difference is coming from 2 hot conductors ie: 240V L-L or 240V L-N?

Sure, you can also run your 3 phase 480 volt motors on 415 volts without problem.

 

[mbrooke]

415/240V for a datacenter is not unusual. What IS unusual is that the utility would provide the secondary voltage at 415/240V.
Every data center that I do at 415/240V, I get a 480/277V utility service, and split off the HVAC feeders and feeders for the UPS / IT equipment and only step down the IT feeders after the nominal 480V UPS.
With a 415/240V utility service, your choices of native 415/240V UPSs with a UL listing will be slim (guessing you will have a UPS and this is a US installation). You will likely have to step up and back down at the input / output of a typical 480V UPS if you are being serviced by 415/240V from the utility, and affect the efficiency.

400-416 volt pad mounts are becoming common as the demand for 415 volt services increases.


https://www.t-r.com/cart.php#!c=c&l=...=400y/230&tp=+

https://www.t-r.com/cart.php#!c=c&l=...=416y/240&tp=+

https://www.t-r.com/cart.php#!c=c&l=...&sv=y/240&tp=n

For the efficiency gained, it makes sense to just provide it at the service eliminating an internal transformation level.

 

[Besoeker3]

Hi All,
I am designing a small server farm that is being fed by the local utilities with (2) 2500KVA 415/240V 3PH 4W transformers. This is being done so that the servers can utilize 240V L-N at the PDU outlets. The customer would like to use multiple 1/2hp exhaust fans to exhaust the hot air & bring in fresh air. These motors are rated 115V/208-230V 1PH. My question is can I hook up these motors 240V L-N using the 230V wiring leads? Do the motor windings care if the potential difference is coming from 2 hot conductors ie: 240V L-L or 240V L-N?

Those voltages are like UK voltages rather than US voltages. Is the frequency a possible issue?

 

[ron]

400-416 volt pad mounts are becoming common as the demand for 415 volt services increases.


https://www.t-r.com/cart.php#!c=c&l=...=400y/230&tp=+

https://www.t-r.com/cart.php#!c=c&l=...=416y/240&tp=+

https://www.t-r.com/cart.php#!c=c&l=...&sv=y/240&tp=n

For the efficiency gained, it makes sense to just provide it at the service eliminating an internal transformation level.

Agreed, transformers are available in lots of secondary voltages, and I take advantage of that. It is just unusual to me that the utility would provide it as a non-standard secondary voltage.

we also don't do most things in the US at 415/240, so we keep standard voltages for hvac to help with service and replacement parts.

 

[winnie]

Those voltages are like UK voltages rather than US voltages. Is the frequency a possible issue?

No, however the UK/Europe connection is why this is happening in the US.

Most computer switching power supplies these days are designed to function from about 100V - 250V 50Hz-60Hz. They work just fine with 240V L-N, so that the same parts could be used in Japan, North America, Europe, etc. Unfortunately they don't quite handle 277V L-N.

So large computer server farms are being built using 415/240 wye to take advantage of the lower currents, single pole breakers for 240V loads, etc.

It would not surprise me if either power supplies change to use 277V, or if HVAC equipment is designed to operate from 415-480V (much like motors that function at 208V or 240V).

-Jon

 

[mbrooke]

Agreed, transformers are available in lots of secondary voltages, and I take advantage of that. It is just unusual to me that the utility would provide it as a non-standard secondary voltage.

With more and more data centers requiring it, none-standard is becoming an obsolete term.

we also don't do most things in the US at 415/240, so we keep standard voltages for hvac to help with service and replacement parts.

True, but keep in mind those 208-230/460 volt motors should run fine a 416 volts.

 

[ron]

True, but keep in mind those 208-230/460 volt motors should run fine a 416 volts.

I can see how a 230V single phase motor would be fine on 240V L-N, but a 460V motor running on 416V is right on the low end of a 10% service factor. Seems too close for me.

 

[mbrooke]

I can see how a 230V single phase motor would be fine on 240V L-N, but a 460V motor running on 416V is right on the low end of a 10% service factor. Seems too close for me.

But consider that 230 volt motors are run on 208 volts all the time.