NEC standrad for voltage unbalance for motors
NEC standrad for voltage unbalance for motors
(OP)
Hi Members
Is their any NEC standrad for acceptable level for unbalance voltage for induction motors
Is their any NEC standrad for acceptable level for unbalance voltage for induction motors






RE: NEC standrad for voltage unbalance for motors
The NEC does not specify, but another ANSI standard—C84.1-1995 [Annex D] discusses derating for unbalanced-voltage operation.
Use the search function at this site. It has been discussed at length here.
RE: NEC standrad for voltage unbalance for motors
http://www.nema.org
for MG-1 motor and generator standard
Also, military standard
MIL-STD-1399(NAVY)
SECTION 300A
13 October 1987
SUPERSEDING
DOD-STD-1399(NAVY)
SECTION 300
1 August 1978
(See 6.3)
for the voltage unbalance limit 3% of Type I and II power supplies and 2% for Type III power supply (400Hz)
RE: NEC standrad for voltage unbalance for motors
NEMA recommends against the use of motors where the unbalance is greater than five percent.
A unbalance of one percent may already void a manufacturer's warranty.
RE: NEC standrad for voltage unbalance for motors
RE: NEC standrad for voltage unbalance for motors
According to ABB protective-relay literature, induction-motor current imbalance is equal to
voltage imbalance x motor locked-rotor current / motor full-load current
RE: NEC standrad for voltage unbalance for motors
Short IEEE online article on voltage-unbalance assessment: http://grouper.ieee.org/groups/1159/1/VUFAss.html
RE: NEC standrad for voltage unbalance for motors