That 30KW surplus capability will be wasted 99% of the time, and conceivably cause some cold stacking. A soft start of the heaters may be as simple as pre warming them on 110V for a few seconds before switching 220V to them. - Simple relay function, and may make a 25 - 30KW gen quite sufficient.The total cost of a 50KW generator installation vs a 20 KW generator installation is minimal and certainly cheaper than Jerry Rigging something to make a 20KW limp along.
I don't know the qualifications of the posters (may be sterling) but I think the OP should contact the technical side of the XRay machine manufacturer and talk to an engineer about alternatives. This issue has to be a common problem where these machines are used in emergencies or in less developed countries where power is less reliable and / or robust.
Yes. But I suspect that the heater surge is longer. Still, its the high surge level that is the problem for a genny, and it is almost definite that the level could be lowered significantly by appropriately spreading the time of the initial and subsequent short heater cycles.
... I would 1st get an electronics guy to look at the machine schematics and query the xray mfg knowledgably. Heaters are pretty simple, not rocket science, and softer usage would prevent the significant oversizing of the gen that is being proposed to cover the abusive uncontrolled surges.
That 30KW surplus capability will be wasted 99% of the time, and conceivably cause some cold stacking. A soft start of the heaters may be as simple as pre warming them on 110V for a few seconds before switching 220V to them. - Simple relay function, and may make a 25 - 30KW gen quite sufficient.
Yes, but the heat would cause the resistance of the heater to rise some. And then hitting it with 240 would not cause so great an inrush. ... Plus, it would be barely more difficult to use a rotary switch to step through the outputs of a multi tapped transformer starting at whatever voltage and then up in several steps from there to the full 240.120V on heaters designed for 240V will only produce 25% of the design heat.
A spark ignition engine will operate at part load without wet stacking , a diesel will wet stack.
To heat the wire for thermionic emission to occur, rather than use high voltage which would push electrons through the filament faster, what is needed is high amperage which results in millions more electrons trying to crowd their way through the filament, thus causing great friction.
The wires in the cathode are thin in order to create greater friction. It only takes seconds for this wire to heat but the amp draw is enormous.
Two currents are used in this machine (and all others) After high amps do their job, high voltage takes over to produce the actual imagery.
Indeed this is a digital machine.
,,,,,,,,,,,These are incandescent heaters. Inrush to a 100W bulb is 13A, dropping to 0.8A as the filament heats -- a 16 fold drop. While the cathode heaters in the xray vacuum tube may not exhibit this phenom to such extent, they will exhibit it. Even a 2 fold drop opens all kinds of possibilities.
Yes, but the heat would cause the resistance of the heater to rise some. And then hitting it with 240 would not cause so great an inrush. ... Plus, it would be barely more difficult to use a rotary switch to step through the outputs of a multi tapped transformer starting at whatever voltage and then up in several steps from there to the full 240.
I didnt say anything about a hand operated switch. Rotary switches can be easily automated by instituting timed steps. The control would be designed to the need, and the warming sequence would be transparent to the user other than a longer warmup. Software may also have to be fooled in a microprocessor controlled machine. ... The person modifying would have to pay attention and employ the most suitable methods. Employing a rotary switch in the design is just one possibility.Why go complicated with a hand operated mechanical switch and having to train everyone to operate it ? Just use a VFD to ramp up voltage and current .