extended voltage range motors.
extended voltage range motors.
(OP)
In going through specifications, I have consistantly encountered the statement: "Extended voltage range motors shall not be permitted". What are these type of motors, and why are they apparently so bad to use.





RE: extended voltage range motors.
My personal opinion is that the optimum performance of a motor fits only one voltage and frequency. A motor could work in a broad range of voltage and frequency but with detrimental characteristics like; Efficiency, Power Factor, Torque and temperature rise.
RE: extended voltage range motors.
Barry1961
RE: extended voltage range motors.
RE: extended voltage range motors.
Could you please explain the relationship of "Extended voltage range motors" with "dual voltage motors" in your post?
RE: extended voltage range motors.
The (200)208- versus (230)240-volt compromise is described in a “treaty” of sorts between a committee of electric utility and appliance-/equipment-manufacturer representatives, currently in ANSI{NEMA} Std C84.1-1995 Electric Power Systems and Equipment—Voltage Ratings (60 Hertz)
The matter is further complicated in that constant-resistance-load power varies with the square of terminal voltage, and electromagnetic devices are closer to constant-kVA, where, roughly, current decreases with increased terminal voltage.
[Coincidentally, the ‘gap’ shows up at 4.16-4.8, 12.0-13.8 (or 14.4) and 115-138kV levels. The voltage ratio is very close to (2-√3)/2, where inherently a factor of 2 relates to equal series/parallel components and √3 relates to ø-ø/ø-n quantities.]
IEEE Std 141-1993 [Red Book] Chapter 3 discusses ‘accepted norms’ in fair detail, but still leaves the end user with less-than-ideal circumstances for most efficient operation over a ~13% voltage span.
RE: extended voltage range motors.
e.g.
ANSI Motor Nameplate
208V 200V
240V 230V
480V 460V
4.16kV 4.0kV
etc.
The reason for this is that the motor manufacturers and associated standards e.g. NEMA expect the motor terminal voltage be lower than the ANSI system voltage due to the voltage drop in the motor feeder, which is not a bad idea.
RE: extended voltage range motors.
jbartos.
Could you please explain the relationship of "Extended voltage range motors" with "dual voltage motors" in your post?
///These expressions are often used interchangeably, probably because they are not defined in IEEE Std 100 Dictionary. However, dual voltage motor expression is often related to a different motor design, e.g. 230V/460V(240V/480V) motor nameplate rated.
Visit
http://www.sannet.gov/mwwd/business/cwpspecs/pdf/16040.pdf
for:
1. Motors below 1/2-hp shall be rated 115 volts, single-phase, 60-Hz. Dual voltage motors rated 115/230-volts, 115/208-volts, or 120-240 volts are acceptable.
2. Motors 1/2-hp and larger shall be rated 460 volts, or 4160 volts, 3-phase, 60-Hz. Dual voltage motors rated 230/460 volts or 208/230/460 volts are acceptable.
http://www.usmotors.com/SP101/footnotes.pdf
etc. for more info\\\