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Need advice on lowering hi leg voltage

Matt100

Plastic
Joined
Aug 14, 2008
Location
Michigan
Hi everybody, I'm new to this forum. There seems to be some very knowlageable folks here.

I receintly moved my shop home and I,m still trying to get everything smoothed out. I,m running 2 Kiamura Mycenter 1"s and a 10 screw aircomp from a phase perfect 30 hp digital, with a 32volt buck on the single phase side. Phase perfect claims balanced voltage and delivers between the legs, however, as with RPC's it still has a hi manufactured leg when checking back to ground. My Fanuc OM controled My1 has no problem but the Yasnac I80 control ocationaly goes into a hi voltage input alarm on the spindle drive. It only does so during starting or stopping, never when cutting. I have the hi leg wired to T3. Kitamura says it it the hi leg causing the problem and recomended a that I install an isolation transformer, claiming that will calm down the hi leg while maintaining phase voltage balance. I have no problem doing so If that is the right way, however I am interested if there are any more simple, cheaper ways. I have a good friend who runs 3 Yasnac I80 controls from Rpc's and he has never had this problem. Opinions please.
Thanks, Matt
 
"Phase perfect claims balanced voltage and delivers between the legs, however, as with RPC's it still has a hi manufactured leg when checking back to ground."

PP is not referenced to ground.

It takes the two single-phase lines and converts it into high-voltage dc using a special type of converter, one which works both ways. Then, it takes the high-voltage dc and inverts that into a single high-voltage ac source. By adding and subtracting the incoming L1 and L2 to and from this high-voltage ac source, three identical phases are produced. And, the PP can absorb regenerated power, which an RPC cannot do.

The PP presents a ∆ source and load to the utilization equipment. There should be no neutral. And, as there is no neutral, there can't be a high-leg in the conventional sense.

If you must have a neutral, and you intend to have B-N as 208, whereas A-N and C-N are 120, then you may have to use two buck transformers. One, call this AT1, from L1 to N, and producing L1-1. Another, call this AT2, from L2 to N, and producing L2-1. L1-1 and L2-1 would then go to the PP. Then B-N could read 208 as in a normal 120/240 ∆ three-phase system.

Are you using the buck transformer because your single-phase is on the high side of nominal, or because you're trying to produce 200 three-phase to power your Japanese equipment?
 
My single phase voltage is hi at 247. I am currently at 212 on the three phases. The cnc manufacturer said not to exceed 220.
 
My single phase voltage is hi at 247. I am currently at 212 on the three phases. The cnc manufacturer said not to exceed 220.


That is what really irks me, 220 volts does not exist as a standard US voltage
and importers keep bringing in that crap. The line voltage @ 247V is fine for "normal" equipment. That is the # 1 reason I dispise foreign equipment,Europeons and the Chinese are the worst in that reguard.
 








 
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