generator kw rating to drive 100 hp dc motor?

[4504]

hello all

great website. i'm no expert like you guys, so i am asking your estimation of how powerful a diesel generator must be in kw rating in order to drive a magnetek 100 hp d.c.electric motor. all i have on the motor so far is that its 100 hp, 500(480) dc(input?)and the field amps are 5.7./6.04. it is a brushed motor, 3 phase, air cooled, and there is a magnetek dsd 412 drive available for it. its a pretty substantial motor weighing in at about a ton. the motor had been fed 480v shore power. the motor is not with me so i do not have much further infomation right now. the plan is to run it on a boat so any estimates on what kw rating dc diesel generator it would take would be helpful. would it be better to get an a/c genset and let the drive convert it to dc? i was told by one source that it would take a 150 k.w. genset to run this motor, i would be curious to see if any of you guys agree or have another estimate.....thanks, mike

 

[Paulusgnome]

Sorry to say, but there is something here that does not add up.
You say that it is a DC motor. Then you go on to say that it is a "brushed motor, 3-phase air cooled".
It really can't be both. It is either a DC motor (which will most likely have brushes) or it could be a wound-rotor 3-phase induction motor (which will also most likely have brushes).
These are, of course, completely different beasts!

 

[4504]

thanks. i wondered about that too. the only thing i had heard about 1 or 3 phase before was with a/c generators. i am assuming that the reference to phase was in error, however, i will check with the seller. here is a link to a picture of the unit if that helps.

 

[ScottyUK]

Sure looks like a DC machine.


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If we learn from our mistakes I'm getting a great education!

 

[Paulusgnome]

It IS a dc motor - an elevator motor to be exact. A quick google on "magnetek dsd 412" gets you the manual for the drive.
The drive takes a 3-phase ac supply, and supplies dc to the motor, perhaps this was the source of the confusion.
As regards the diesel horsepower needed to run the 100hp motor, this will depend on the load that the motor is driving and the speed it is driving it at.

 

[waross]

Most DC machines of that size are interchangeable as motors or generators. Buy two motors and turn one with a diesel engine to supply the energy to run the second. You will also need to turn an exciter to supply the fields.
you will need about 120 true Hp, not marketing Hp. If you are using the drive that was designed to run the motor from 3 phase, you will have to check the input rating of the drive. then you may have to go as much as 200% to cope with harmonics.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[4504]

thanks for the replies. the motors would be spinning a 2" shaft, variable rpms 0-850 with reverse capability, the drive itself is rated at 125 hp, voltage 150v-525v, power range 25-1270 amps run current. page 11 of the attached pdf has specifications. these motors and drive were previously used in a drawbridge.

anybody have a guess at the kw rating for a generator?

 

[waross]

Go to table 22 on page 104 and tell us what model drive you have and what voltage it is rated for.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[4504]

thanks, i should have that information within a few days, i'll post it as soon as i get it. i really appreciate everyone's help....mike