Motors over 500 HP
Motors over 500 HP
(OP)
Table 430.150 provides the full load current for certain motors up to 500 HP. How do I find the current (for sizing conductors) if the motor is larger than 500 HP?
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Motors over 500 HP
RE: Motors over 500 HP
208V = 2.75A/HP
230V = 2.4A/HP
460V = 1.2A/HP
575V = .96A/HP
2300V = .24A/HP
4160V = .14A/HP
Note that these are for ESTIMATING only. NEVER use anything other than the motor nameplate FLA for protection device settings etc.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Motors over 500 HP
Ifl = HP*0.746 / ( 1.732*kVll*EFF*PF)
Assume EFF = 0.90 and PF=0.87, for instance 1000 HP at 4160 or 2300 Volts.
Ifl = 1000*.746 / ( 1.732*4.16*0.90*0.87) = 132.23 Amps @ 4160 V.
Ifl = 1000*.746 / ( 1.732*2.3*0.90*0.87) = 239.17 Amps @ 2300 V
For accurate calculation you need the EFF and PF from the manufacturer for each specific motor and load. Those figures (EFF & PF) change when the load changes and from different model or manufacturer.