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#88643 - 07/02/04 05:41 AM V.F.D. calcs
Yoopersup Offline
Member

Registered: 03/04/03
Posts: 826
Loc: Michigan
30 Hp with V.F.D.
430.6 & 430.150
30 hp =40amps at 460 volts
40x150%=60amps
wire size=3#6s &1#10
Disconnect Switch=60amp
Should disconnect switch be up sized to 100 amp (fuseable).Seems to be hitting it right on the mark? wondered if maybe to close??

75hp 460v 3 phase (96 amps)
96x150%=144 amps
wire size=3#1s&1#8
Disconnect switch =100amps

Hows it look guys don;t have into off name plates of VFD so using 430.6c

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#88644 - 07/02/04 05:43 AM Re: V.F.D. calcs
Yoopersup Offline
Member

Registered: 03/04/03
Posts: 826
Loc: Michigan
Opps Disconnect switch 150 amps not 100 amps

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#88645 - 07/02/04 06:41 AM Re: V.F.D. calcs
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Take a look at 430.2.

I do not see an option for using the tables as far as the VFD is concerned.

[This message has been edited by iwire (edited 07-02-2004).]
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#88646 - 07/02/04 06:52 AM Re: V.F.D. calcs
Yoopersup Offline
Member

Registered: 03/04/03
Posts: 826
Loc: Michigan
430.6c
If the maximum operating current does not appear on the nameplate ,the ampacity determinated shall be based on 150% of the valves given in tables 430.149 and 430.150.

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#88647 - 07/02/04 06:57 AM Re: V.F.D. calcs
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I do not see that 430.6(C) changes the requirments of 430.2
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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