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hjl4 said:I am also confused here.
5 thousand volt /amp??
He does say DC.
One major project on the way here.
But yes, Styx pretty much summed it up.
Either way........ Expensive.
Oznog said:I'm going to go out on a limb and say this is likely beyond the experience of anyone here. And we don't know the best way to manage armature vs field for that particular motor at the type of load you've might be using. I suggest you talk to the mfg of the equipment on how to drive it.
Styx said:*cough* not me, thats my job *cough*
Styx said:He said 5kVA ? The fact he is talking in VA and not WATTS is implying that he is taking power from an AC network
So for a unity power facor (it wont be) that is 5kW which is tiny.
Even if it was 5000V, that is only 1A of AC current.
For the UK mains
3ph power: => AC current of 4.1A
single phase power => AC current of 21A
I dont see the problem, this is small fry. I am more concerned with the use of a brushed DC
Oznog said:He said "5000 KVA", not "5KVA". As in 5MVA!
5kVA dc motor
I'll try but I am not going to give him an inverter just like thatOznog said:Styx said:*cough* not me, thats my job *cough*
Ah, he's in luck then!
Oznog said:Styx said:He said 5kVA ? The fact he is talking in VA and not WATTS is implying that he is taking power from an AC network
So for a unity power facor (it wont be) that is 5kW which is tiny.
Even if it was 5000V, that is only 1A of AC current.
For the UK mains
3ph power: => AC current of 4.1A
single phase power => AC current of 21A
I dont see the problem, this is small fry. I am more concerned with the use of a brushed DC
He said "5000 KVA", not "5KVA". As in 5MVA! This is consistent with the scale of a 3K HP motor and a 2.4KA/750VDC power supply. So I don't think it's a typo. The scale's 1e+3 bigger than you think.
Styx said:For the UK mains
3ph power: => AC current of 4.1A
single phase power => AC current of 21A
Styx said:please go back and re-read his post.
JimB said:Styx said:For the UK mains
3ph power: => AC current of 4.1A
single phase power => AC current of 21A
The single phase case I can understand, but how did you arrive at 4.1A for the three phase /?
With a phase voltage of 415v and a PF of 1, I get 7Amp.
Am I missing something?
JimB
hjl4 said:I'm sure most of you know this.
KVA: Kilovolt amperes (1000-volt amps).
kVA is obtained simply by Amps x Volts divided by 1000.
hjl4 said:Were all speculating here, so maybe we'd better wait and see if AMAECHI
will give us more details. Until then I prefer to stay out of this one.
BTW, anybody know what kind of machine a 5000 Volt, dc motor could be running? Seems rather large.
Styx said:For a 3ph system again working with phase voltage
5kW = 3 * Vph * Iph
5000 = 3 * 230 * Iph => Iph = 7.2A
So yup you are correct, I took line voltage by mistake that 1st post
JimB said:Styx said:For a 3ph system again working with phase voltage
5kW = 3 * Vph * Iph
5000 = 3 * 230 * Iph => Iph = 7.2A
So yup you are correct, I took line voltage by mistake that 1st post
OK I see the way you were thinking.
I usually think it as W = sqrt(3) x Vline x Iline x Cos(phi).
Your way has an extra sqrt(3), but you use the phase voltage rather than the line voltage so it cancels out.
JimB