Three phase voltage level in US.
Three phase voltage level in US.
(OP)
What is the "normal" three phase voltage in the US ?
440V, 460V or 480V ?? Offshore is normally 440V but motors made in US are 460V and someone claims 480V. Do you use 460V motors as a standard?
Since I'm in Europe I have no clue, but need the info....
Audun
440V, 460V or 480V ?? Offshore is normally 440V but motors made in US are 460V and someone claims 480V. Do you use 460V motors as a standard?
Since I'm in Europe I have no clue, but need the info....
Audun






RE: Three phase voltage level in US.
Please refer ANSI C84.1-Electric Power Systems & Equipment Voltage Ratings (60 Hz) for nominal voltages based on ANSI/ IEEE which are widely used in NA.
Kiribanda
RE: Three phase voltage level in US.
RE: Three phase voltage level in US.
Different categories are centered around terms—Equipment Nameplate Voltage Rating and Nominal System Voltage.
A terse abridgement of C84.1-1995 is ARI Std 110-2002 for systems 600V and under.
www.ari.org/std/forms/110.html is free to "qualified" recipients... (Form to complete)
[C84.1-1995 is a for-fee publication by the National Electrical Manufacturers Association, described at nema.org]
RE: Three phase voltage level in US.
"Venditori de oleum-vipera non vigere excordis populi"
RE: Three phase voltage level in US.
The American National Standards Institue Class A limit is 110 to 120 volts against a 120 volts base. Multiply for other other voltages. The class B limit for short term abnormal conditions is 105 to 125 volts.
The voltage goal is 120 volts at the secondary terminals of the distribution transformer. After allowing for voltage drop the motor needs to be able to operate at 440 to 480 volts under normal conditions and 420 to 500 volts abnormal.
Most of out 230/460 volt dual voltage motors are now designed able to tolerate operation off of a 120Y208 volt commercial power system using only 1 connection for both 120Y208 volts and 240 volts. Thanks to advances in insulation and magnetic materials the only 200 volt motors still being made are specialized motors such as submersible well pump motors. I have also seen motors built to run on 50 Hertz 220Y380 volts (Britsh) 500 volts (German) and 60 Hertz 416 volts (Australian and Paraguayan) and 480 volts (US) without changing any taps - the machine has dual diameter belt sheaves for dual frequency operation.
How we have 120/240 volts 4-wire delta 3-phase a.k.a. red leg delta a.k.a. rural delta was to have a cheap way to supply farms and residential air conditioning with cheap 3 phase power. Two transformer in the open delta configuration would be used to supply small amounts of 3 phase and in the case of load growth we would upgrade to 3 transformers using a 3-wire wye primary. The National Electrical Code official color for the high leg is orange but that conflicts with the 277Y480 volt colors - I would use orange with red stripes as a compromise.
Back in the mid 1960s central air conditioners had to be 3 phase because single phase motor technology was not good. Even though todays single phase air conditioners are better some utilities have gone back to requiring residential ari conditioners and heat pumps that are over 36,000 BTU per hour to be 3 phase. This is because a 3 ton heat pump has a 4.5 horsepower freezer compressor in it anything over that size needs to be 3 phase.
Mike Cole, mc5w@earthlink.net