Motor nameplate data
Motor nameplate data
(OP)
Motor conductors selection is typically based on the nameplate current (FLA). However, the Standard MG1 allows motor manufacturer a deviation of 10% from the rated value.
Does this constitute a requirement to factor these additional 10% when selecting a conductor size?
Does this constitute a requirement to factor these additional 10% when selecting a conductor size?





RE: Motor nameplate data
RE: Motor nameplate data
In this case NEC tables do not apply.
RE: Motor nameplate data
RE: Motor nameplate data
In this specific case (VFD driven motor) the Article 430.6(C)applies, which has a reference to nameplate rating. We already confirmed the applicability of this article with local Authority Having Jurisdiction. My question actually was about additional 10% of current. Seems that MG1 allows for that, but NEC does not address this factor.
RE: Motor nameplate data
RE: Motor nameplate data
RE: Motor nameplate data
"Motor conductors selection is typically based on the nameplate current (FLA)" Yes,if you use the wire manufacturer tables and derrating factors(room temperature and number of wires in duct) you most have to take account too the leads number and motor connection.For practical matters The FLA could be oversized by 10%.
For the inverter rated motors, use the motor´s current at 60 Hz.The most commun motor´s wires manufacturer use EPDM ,HYPALON, SILICONE AND GLASS Materials.
This link could help:www.belden.com
Regrads
Petronila
RE: Motor nameplate data
430.6(C) does not mention frequency, but the definition "For motors used used in AC, adjustable voltage, variable torque drive systems" fully applies to VFD configuration, and I repeat, we had no problems to get it confirmed officially.
RE: Motor nameplate data
RE: Motor nameplate data
This is enough to cover a 10% deviation.
Can you give us the wording of MG11?
respectfully
RE: Motor nameplate data
The quote from MG1 (Condensed) : "When operated at rated voltage, rated frequency and rated horsepower output, the input in amperes shall not vary from the nameplate value by more than 10 percent"[MG1-12.47]
RE: Motor nameplate data
respectfully
RE: Motor nameplate data
I do not believe this statement applies to motor running from a VFD. The "rated voltage, rated frequency" means a sine wave.
NEMA standards for ac motor are based on operation from a sine wave unless specifically stated otherwise. This includes standards for efficiency and power factor.