450v???

[Mister Kool]

By the contractors mistake a 15000V/13500V primary/480V secondary transformer was just installed in a university building. it replaced a 12500V/480V transformer. The lowest taps on the new transformer is 13099V for primary BUT the primary voltage that is available is only 12400V thus the new transformer is only putting out 450V phase to phase and 260V phase to ground, opposed to the 480/277V that was put out previously. The motors and elevators are running the IT area is up and running BUT vill the lover voltage pose a power problem in the future????

 

[jim dungar]

BUT vill the lover voltage pose a power problem in the future????

Yes, low voltage will cause devices to draw more current. More current equals more heat. Devices running hot usually result in less life expectancy.

 

[zog]

By the contractors mistake a 15000V/13500V primary/480V secondary transformer was just installed in a university building. it replaced a 12500V/480V transformer. The lowest taps on the new transformer is 13099V for primary BUT the primary voltage that is available is only 12400V thus the new transformer is only putting out 450V phase to phase and 260V phase to ground, opposed to the 480/277V that was put out previously. The motors and elevators are running the IT area is up and running BUT vill the lover voltage pose a power problem in the future????

Yep, you have a problem, time for the right transformer. Not sure how someone missed that one?

What is the kVA? Dry or oil?

 

[LarryFine]

The low-voltage-caused current increase could also overload closely calculated and sized conductors and other equipment.

 

[sameguy]

Any taps on the xformer ?

 

[Cow]

The lowest taps on the new transformer is 13099V for primary BUT the primary voltage that is available is only 12400V thus the new transformer is only putting out 450V phase to phase and 260V phase to ground, opposed to the 480/277V that was put out previously.

.....

 

[iwire]

The low-voltage-caused current increase could also overload closely calculated and sized conductors and other equipment.

I would be surprised if the drop from 480 to 450 would raise the current, I bet in 'real life' the current would reduce.

 

[G._S._Ohm]

Resistive load = less current.
Motor load = probably more current.
Compressors may have difficulty starting.

It's a 6% voltage reduction.

IMO, if the incoming line voltage is consistently at the high end of the tolerance band and the loading is consistently light you might not notice any early equipment failures over the next several years.
It's a gamble.

 

[robbietan]

By the contractors mistake a 15000V/13500V primary/480V secondary transformer was just installed in a university building. it replaced a 12500V/480V transformer. The lowest taps on the new transformer is 13099V for primary BUT the primary voltage that is available is only 12400V thus the new transformer is only putting out 450V phase to phase and 260V phase to ground, opposed to the 480/277V that was put out previously. The motors and elevators are running the IT area is up and running BUT vill the lover voltage pose a power problem in the future????

It depends on the voltage of your loads. motors generally like the voltage a wee bit higher than their nameplate rating but electronics would prefer their voltage a wee bit lower than their rating. A dilemma, thats what it is

However, if the motor is rated for 480V , the voltage swings from the supply must only be from 432V to 528V for the motor to function properly. Any voltage beyond these limits may damage the motor.

 

[charlietuna]

Most utility specs call for them to provide 480 volts---plus or minus 10%. Which allows a low end voltage of 432 to be within their spec. The time of the day might have a lot to do with your reading of 450 volts between phases. This was common during early mornings in large building area services while buildings were coming "on line" with all their air conditioning loads. If they corrected for "low readings" in the mornings, they might be over 600 volts in the afternoon.

 

[zog]

Most utility specs call for them to provide 480 volts---plus or minus 10%. Which allows a low end voltage of 432 to be within their spec. The time of the day might have a lot to do with your reading of 450 volts between phases. This was common during early mornings in large building area services while buildings were coming "on line" with all their air conditioning loads. If they corrected for "low readings" in the mornings, they might be over 600 volts in the afternoon.

I think NERC has a 10% variance limit, so +/- 5%.