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21
Our Shop / Re: The is a rotary phase converter question
« Last post by Alphawolf45 on February 15, 2019, 01:45:20 PM »
 Well I read it on the internet so you know it has to be right :doh:
  Anyway you have all convinced me that it can be done but it is beyond my set of skills...
      The generator offers bonus that we sometimes lose power to the house and wife has been on me to get a generator......Uhmmm Now can somebody give me a ballpark figure on kilowatts required to feed a healthy 200 amps of 220 3 phase to my shop? Pulling a number out of the air I am guessing that 100 KW would be necessary.
   By the way , I have an even dozen 3 phase machines in my shop if I only count the ones that work.. And for those I manage nicely with a 5 hp rotary phase converter aside from that power sucking EDM.
22
Tools / Re: Did I Overdo the Files ?
« Last post by Pete. on February 15, 2019, 12:32:51 PM »
I thought you said FLIES then and it reminded me of a scene from 'Something about Mary' :D :Doh:

23
Our Shop / Re: The is a rotary phase converter question
« Last post by John Rudd on February 15, 2019, 12:09:22 PM »
I've seen pictures of the effect of a large turbine set being loaded onto the National Grid when not in phase. The main turbine shaft was bent then sheared and at a guess it was about 15" diameter !

I assume that their synchronising equipment was faulty.

I'm surprised any shears pins would have failed at a coupling, if fitted...maybe not.... :doh:

We actually sheared a coupling on one of our 3.6 MW gen sets, starting a 2.1 MW Regrigeration compressor...even though the motor was on an autotransforner starter...something went wrong, I forget what!.. :Doh:
24
Our Shop / Re: The is a rotary phase converter question
« Last post by timby on February 15, 2019, 11:23:57 AM »
I think it would be best to ask the manufacturer, someone will have tried that before.
25
Our Shop / Re: The is a rotary phase converter question
« Last post by awemawson on February 15, 2019, 11:06:01 AM »
I've seen pictures of the effect of a large turbine set being loaded onto the National Grid when not in phase. The main turbine shaft was bent then sheared and at a guess it was about 15" diameter !

I assume that their synchronising equipment was faulty.
26
Our Shop / Re: The is a rotary phase converter question
« Last post by John Rudd on February 15, 2019, 10:54:28 AM »
The rpc in essence seems simple enough....treat it as a 3 phase supply.
Now add a 3 phase generator.....The issue now is how to synchronise the 2 supplies...

My experience with 3ph, we had to sync up a generator to the local supply. This was done by speeding up or slowing the prime mover..( a 3.6 MW gas generator...)

So now to paralleling 2 rpc's.... I would expect there to be a slight phase difference between them due to tolerance allowances in the capacitors and also the motors....the cap values wont be exact and the motor speeds wont be exact....slip, frictional losses etc...

I wouldnt do it...easier just to get a bigger rpc or a diesel gen set...
27
Tools / Re: Did I Overdo the Files ?
« Last post by hermetic on February 15, 2019, 09:41:51 AM »
Of course you overdid the files! We are engineers Andrew, we overdo everything!!
28
Our Shop / Re: The is a rotary phase converter question
« Last post by seadog on February 15, 2019, 07:49:49 AM »
There will be, but on two identical RPCs they shouldn't be that different. Once you get over the initial connection, in reality there should be no difference between two RPCs running in parallel, and adding in an extra motor and capacitors.

The problem is synchronising the two outputs. Unless they peak and trough at the same time they cancel out.
29
Our Shop / Re: The is a rotary phase converter question
« Last post by Alphawolf45 on February 15, 2019, 06:21:33 AM »
I got the idea for two rotary phase converters from the suggestion of a major rotary phase converter manufacturers website..
    I wouldn't like using a 40hp rotary phase converter every time I wanted to use the edm . The diesel or propane generator idea has real merit for running the injection molding machine.. I've seen decent old biguns for 3 or 4 thousand dollars.. 'Believe I'll start looking for one in another month after I have tests at the oncologist saying my cancer is indeed in remission. I have real 3 phase on a pole in my yard but would be a problem getting it into my shop because of big trees that would need to be taken down. And too, the cancer I had usually returns in 5 to 8 years so I don't need to be initiating another electric bill with cost of poles and transformers added in every month for who knows how long.
30
Our Shop / Re: The is a rotary phase converter question
« Last post by mc on February 15, 2019, 04:59:47 AM »
There will be, but on two identical RPCs they shouldn't be that different. Once you get over the initial connection, in reality there should be no difference between two RPCs running in parallel, and adding in an extra motor and capacitors.
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