spectra physics 265

[teknofon]

does the spectra physics 265 exciter have over voltage protection?

[Laserman532]

does the spectra physics 265 exciter have over voltage protection?

yes the entire pass bank will act like a fuse. you need to be more descriptive as to what you are experiencing. That is an open ended question that could take days of typing. It is important to try to find out what it is not to find out what it isnt.

[teknofon]

i´m using a autotransformer stepping down from 400v to 208v
and i want to protect the psu from getting fried if the trasformer malfunction

[Laserman532]

what are the odds of a transformer malfunctioning? I would place it lower than ...lets say...50%...

you are required to supply 208 vac 3 phase at 50 amps...anything else is a crap shoot. If you can not guarantee that...may be another plan would be necessary.

[Stoney3K]

what are the odds of a transformer malfunctioning? I would place it lower than ...lets say...50%...

you are required to supply 208 vac 3 phase at 50 amps...anything else is a crap shoot. If you can not guarantee that...may be another plan would be necessary.

The old autotransformers will step down from 400V to about 220-230V as they expect the 'old' European threephase current which was 380V line voltage.

Our 265 runs fine off 230V line, though.

Here's a random thought: Would it be possible to use the 3ph neutral of a European three-phase as one of the line connections (so using L1-L2-N, effectively wiring it as two-phase wye), and yield 230V line voltage in triangle directly? I doubt the 265 rectifier worries much about the phase angle, but that's a big IF, if it's a full 3ph bridge rectifier.

Sure, it would place a serious load on your neutral current, but you can balance that by using the leftover phase for any support equipment.

BTW, the actual current draw on those phases is WAY under 50 amps. I'll have to check on the PSU, but IIRC, the breaker fitted to ours was rated lower than 50A. We stepped down from a 16A threephase supply, ran at full 30-35A tube current and never blew any 400V fuses. Some clever math would tell you that the actual draw in that case is somewhere near 32A on the 230V side, tops.

[Laserman532]

the input line specification is 208 vac 3 phase +/-10% when measured from phase to phase with an earth ground at 50 amps. As long as your voltage is between 187.2 vac and 228.8 vac phase to phase you should be fine, anything else...no comment....

the reason for 50 amp supply was that some -09 SP lasers were set to operate at 38 amps and you have the magnet that can run from 4 to 8 to 10 amps depending on which magnet you have.

so anyway... that is what is required, that dosnt necessarily mean that is what will be supplied.

[Stoney3K]

so anyway... that is what is required, that dosnt necessarily mean that is what will be supplied.

... Or that it will/won't work!

Does the PSU have any specs on the phase shift between the lines? If not, the L1-L2-N trick can work out in our favour and we can dump the big piece of iron altogether.

I doubt you'll find any autotransformers that step down from 400V to 208V +/-10% these days, though. The European grid has a tendency to fluctuate like mad, one day we have 218V out of the wall sockets, the other it's more towards 235-240V.

Frankly, I don't think the passbank would suffer a lot when the voltage is on the high side. If the thing is just a big version of your average linear regulator, the only thing to worry about would be a little more cooling.

[Laserman532]

... Or that it will/won't work!

Does the PSU have any specs on the phase shift between the lines? If not, the L1-L2-N trick can work out in our favour and we can dump the big piece of iron altogether.

I doubt you'll find any autotransformers that step down from 400V to 208V +/-10% these days, though. The European grid has a tendency to fluctuate like mad, one day we have 218V out of the wall sockets, the other it's more towards 235-240V.

Frankly, I don't think the passbank would suffer a lot when the voltage is on the high side. If the thing is just a big version of your average linear regulator, the only thing to worry about would be a little more cooling.

experiments are where science and physics collide

[mixedgas]

Frankly, I don't think the passbank would suffer a lot when the voltage is on the high side. If the thing is just a big version of your average linear regulator, the only thing to worry about would be a little more cooling.[/QUOTE]
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That is great way to make shorted to3 cases, 12-20 of them, in about 3 milliseconds after the first power line zero crossing. It will rip through the magnet driver section of the passbank even faster.

Vpassbank + Vtube HAS to equal rectified line once the tube starts.

Steve

[Stoney3K]

Vpassbank + Vtube HAS to equal rectified line once the tube starts.

Steve

That's exactly the behavior of a linear regulator (albeit a big one). A simple LM7805 will also drop 7V at the load current when it's fed 12V of input voltage.

But I doubt the passbank would be able to get about a dozen kW of power out of the cooling line when you feed it with 400V... Then again, we might give that a shot with liquid nitrogen! Anyone got a 265 we can sacrifice?

BTW, does anyone (maybe Steve) have some details on the wiring of the interlock circuit? Ours keeps tripping for no apparent reason during power-on, and when it's on it stays on, and the "Master Control" keyswitch doesn't seem to have any function. The system stays on with the switch in either position.

I suspect a previous owner tampered with the interlock circuits and possibly the water flow regulator (bypass) valve for a quick-and-dirty fix. I'd like to get that back in proper order.