trenurbano
Member
I remember that the voltage range acceptable is +/- 5% but I can no find the documentation to prove this statement. I already found that the voltage drop acceptable is 5% but I still can not find anything about the + 5%. Help?
Voltage range for 480AC
- Thread starter trenurbano
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- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Voltage range for 480AC
You won?t find it in the NEC. The NEC says that keeping the combined voltage drop in the feeders and branch circuit conductors to below 5% should provide acceptable performance. It says that in a Fine Print Note, and it is therefore not a code requirement. As to the + 5%, each manufacturer should specify what is acceptable for their equipment.
You won?t find it in the NEC. The NEC says that keeping the combined voltage drop in the feeders and branch circuit conductors to below 5% should provide acceptable performance. It says that in a Fine Print Note, and it is therefore not a code requirement. As to the + 5%, each manufacturer should specify what is acceptable for their equipment.
bphgravity
Senior Member
- Location
- Florida
Re: Voltage range for 480AC
The NEC provides a definition of Voltage, Nominal in Article 100. The FPN directs you to ANSI C84.1 - 1995, Voltage Ratings for Electric Power Systems and Equipment (60 Hz).
You may want to check with the reference.
The NEC provides a definition of Voltage, Nominal in Article 100. The FPN directs you to ANSI C84.1 - 1995, Voltage Ratings for Electric Power Systems and Equipment (60 Hz).
You may want to check with the reference.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Voltage range for 480AC
From IEEE 141 (Red Book) citing ANSI C.84.1-1989:
Nominal System Voltage: 480V
Nominal Utilization Voltage: 460V
Maximum Utilization & Service Voltage: 504V (See note)
Minimum Service Voltage: 456V
Minimum Utilization Voltage: 440V
Minimum Utilization Voltage for Circuits not supplying lighting loads: 432V
Note:
For 120-600 V nominal systems, this is the maximum service voltage. Maximum utilization voltages would not be expected to exceed 125 V for the nominal system voltage of 120, nor appropriate multiples thereof for other nominal system voltages through 600 V; in this case 500V.
There is another "Range B" that permits brief excursions outside these limits.
From IEEE 141 (Red Book) citing ANSI C.84.1-1989:
Nominal System Voltage: 480V
Nominal Utilization Voltage: 460V
Maximum Utilization & Service Voltage: 504V (See note)
Minimum Service Voltage: 456V
Minimum Utilization Voltage: 440V
Minimum Utilization Voltage for Circuits not supplying lighting loads: 432V
Note:
For 120-600 V nominal systems, this is the maximum service voltage. Maximum utilization voltages would not be expected to exceed 125 V for the nominal system voltage of 120, nor appropriate multiples thereof for other nominal system voltages through 600 V; in this case 500V.
There is another "Range B" that permits brief excursions outside these limits.
Re: Voltage range for 480AC
You asked "what would be the acceptable voltage range". But acceptable with who? If your talking about the utility, around the midwest it would be plus or minus 10%. If you are talking about a piece of equipment, the value might vary but such items such as motors are plus or minus 10%. NEC only address a recommended value and that would be after the utility delivers their high or low voltage service.
You asked "what would be the acceptable voltage range". But acceptable with who? If your talking about the utility, around the midwest it would be plus or minus 10%. If you are talking about a piece of equipment, the value might vary but such items such as motors are plus or minus 10%. NEC only address a recommended value and that would be after the utility delivers their high or low voltage service.
brian john
Senior Member
- Location
- Leesburg, VA
Re: Voltage range for 480AC
Jerry:
Not sure in your area and with your equipment but 10% ubder I agree with 10% over bit high.
10% Under at 480 vac is 432 vac
10% Over at 480 vac is 528 vac. I think someone is pushing the limits here.
Jerry:
Not sure in your area and with your equipment but 10% ubder I agree with 10% over bit high.
10% Under at 480 vac is 432 vac
10% Over at 480 vac is 528 vac. I think someone is pushing the limits here.
lady sparks lover
Senior Member
Re: Voltage range for 480AC
Since the nominal is 460V, I would have to say 5% is about fair. For example, I would run a 230V motor on 208 and believe it would run ok, but a 240V on 208, no way!! I might start, but I would guess it would burn out the motor quite fast.
[ June 10, 2004, 09:25 AM: Message edited by: lady sparks lover ]
Since the nominal is 460V, I would have to say 5% is about fair. For example, I would run a 230V motor on 208 and believe it would run ok, but a 240V on 208, no way!! I might start, but I would guess it would burn out the motor quite fast.
[ June 10, 2004, 09:25 AM: Message edited by: lady sparks lover ]
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Voltage range for 480AC
NEMA limits for a motor are +/- 10%. It would be violation of 110.3(B) to operate a 200 volt motor on a 230v system, also when the system voltage gets about 7% greater than the motor voltage the current increases, as the motor magnetic field is saturated.
NEMA limits for a motor are +/- 10%. It would be violation of 110.3(B) to operate a 200 volt motor on a 230v system, also when the system voltage gets about 7% greater than the motor voltage the current increases, as the motor magnetic field is saturated.
charlie
Senior Member
- Location
- Indianapolis
Re: Voltage range for 480AC
The requirements the electric utilities have to live by are usually given by the public service commissions in the state in which it is operating. In here, the Indiana Utility Regulatory Commission holds us to within 5% of nominal. We usually use 13.8 kV substation transformers on our 13.2 kV system in order to have about a 4% overvoltage and we can take our lines quite a bit further before we need voltage regulators.
The requirements the electric utilities have to live by are usually given by the public service commissions in the state in which it is operating. In here, the Indiana Utility Regulatory Commission holds us to within 5% of nominal. We usually use 13.8 kV substation transformers on our 13.2 kV system in order to have about a 4% overvoltage and we can take our lines quite a bit further before we need voltage regulators.
trenurbano
Member
Re: Voltage range for 480AC
Thanks guys for the responses. I'm currently working on a Train System in Puerto Rico and one of our SCADA indications is the overvoltage/ undervoltage alarms in our passenger station sub-station side. These particular sub-stations are 13.2 KV to 480 V.
Thanks guys for the responses. I'm currently working on a Train System in Puerto Rico and one of our SCADA indications is the overvoltage/ undervoltage alarms in our passenger station sub-station side. These particular sub-stations are 13.2 KV to 480 V.
hbendillo
Senior Member
- Location
- South carolina
Re: Voltage range for 480AC
Whenever I review a set of elvator shop drawings there is usually a note that requests voltage be maintained +/- 5%. This is not a code requirements but more a CYA on the part of the elevator manufacturer. You may have similar requests from some of your equipment suppliers. You may need to determine yourself whether it is a legitimate request.
Whenever I review a set of elvator shop drawings there is usually a note that requests voltage be maintained +/- 5%. This is not a code requirements but more a CYA on the part of the elevator manufacturer. You may have similar requests from some of your equipment suppliers. You may need to determine yourself whether it is a legitimate request.
stew
Senior Member
- Location
- federal way,washington
Re: Voltage range for 480AC
No offense meant here but when I was in the motor shop business the engineers who allowed use of 230 volt motors on 208 volt systems were my freinds. Wound lots of motors that were cooked to a nice golden black due to low voltage. The NEMA allowable is a 10% voltage variation and 10% is 207 volts. Any drop in the nominal applied 208 volts and bingo you get a nice cooking.Its whata helps keep a motor shop in business anyhow.
No offense meant here but when I was in the motor shop business the engineers who allowed use of 230 volt motors on 208 volt systems were my freinds. Wound lots of motors that were cooked to a nice golden black due to low voltage. The NEMA allowable is a 10% voltage variation and 10% is 207 volts. Any drop in the nominal applied 208 volts and bingo you get a nice cooking.Its whata helps keep a motor shop in business anyhow.
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