In comp.sys.sun.hardware Benjamin Gawert <bgawert@gmx.de> wrote:
> * Dave:

> > I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
> > is 120 V 400 Hz

> Sounds a bit strange as most aircraft are 115V/400Hz. Besides that, this
> is 3 phase. What type of airplane is it?

> > The specs on the Netra T1 are:
> >
> > 100 - 240 VAC, 47 - 63 Hz, 2 A (max)
> >
> > Has anyone ever tried running one at 400 Hz?

> Not a Sun Netra T1, but other similar equipment. It doesn't work.
> Switching PSUs are designed for a certain AC frequency range. Your
> chances are good to kill the PSU if you connect it to 400Hz.

> Besides that, you should be aware that the Netra T1 isn't certified for
> use in aircraft. Connecting it to aircraft power not only imposes the
> risk of damaging the Netra (which wouldn't be that of a problem) but
> also of causing damage of the aircraft electric systems and avionics
> (and that definitely would be a problem). You can try to get your Netra
> certified for that but that is very costly (i.e. you need to have a risk
> assessment done). Installation must be done by certified technicians. Of
> course you could try to come away with just installing it, but you
> violate the airplanes airworthiness and risk prosecution.

All that depends on how the aircraft itself is certified and under
which set of rules it is going to fly.


--
Jim Pennino

Remove .spam.sux to reply.

In article <4852a4fe@212.67.96.135>, Dave <foo@coo.com> wrote:
>I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
>is 120 V 400 Hz
>
>The specs on the Netra T1 are:
>
>100 - 240 VAC, 47 - 63 Hz, 2 A (max)
>
>Has anyone ever tried running one at 400 Hz? My guess is that it is
>unlikely to be an issue, as the input voltage will soon be converted to
>DC in the switch mode power supply by a bridge and capacitors. A higher
>frequency should have not be an issue there, and if anything gives the
>capacitors an easier time.

Actually the most likely problem would be the bridge. High power diodes
can be quite slow (have a high stored charge) and can overheat if they
are run at a high frequency. There are fast diodes available, but they
cost more and are usually not used if not needed. This is definitely
a problem in the part of the supply where the switching is done as the
frequency there is usually over 20000 HZ. I am not sure if 400 HZ is
high enough to cause problems, but it might be.
If you try it and blow the bridge, most likely the only other thing that
will be killed would be a fuse (I assume it does have a fuse). In that
case the cost of the parts to fix it would not be very high.

>
>Dave

On Fri, 13 Jun 2008 17:49:01 +0100, Dave wrote:

> I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
> is 120 V 400 Hz
> The specs on the Netra T1 are:
> 100 - 240 VAC, 47 - 63 Hz, 2 A (max)

Source or rent a low power frequency converter. See Google

> Has anyone ever tried running one at 400 Hz? My guess is that it is
> unlikely to be an issue, as the input voltage will soon be converted to
> DC in the switch mode power supply by a bridge and capacitors. A higher
> frequency should have not be an issue there, and if anything gives the
> capacitors an easier time.

I wouldnt bet the farm on that. When they say 47-63 and switching PS
I would stay within.

Benjamin Gawert wrote:
> * Dave:
>
>> I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
>> is 120 V 400 Hz

>
> Sounds a bit strange as most aircraft are 115V/400Hz. Besides that, this
> is 3 phase. What type of airplane is it?

It quite possibly is 115. I know I was told it was around that value.
Whether it was 110,115,120 I don't recall, but it will not make much
difference.


>> The specs on the Netra T1 are:
>>
>> 100 - 240 VAC, 47 - 63 Hz, 2 A (max)
>>
>> Has anyone ever tried running one at 400 Hz?
>
> Not a Sun Netra T1, but other similar equipment. It doesn't work.
> Switching PSUs are designed for a certain AC frequency range. Your
> chances are good to kill the PSU if you connect it to 400Hz.
>
> Besides that, you should be aware that the Netra T1 isn't certified for
> use in aircraft. Connecting it to aircraft power not only imposes the
> risk of damaging the Netra (which wouldn't be that of a problem) but
> also of causing damage of the aircraft electric systems and avionics
> (and that definitely would be a problem). You can try to get your Netra
> certified for that but that is very costly (i.e. you need to have a risk
> assessment done). Installation must be done by certified technicians. Of
> course you could try to come away with just installing it, but you
> violate the airplanes airworthiness and risk prosecution.

Thank you for that.



> Benjamin

Thomas Schulz wrote:
> In article <4852a4fe@212.67.96.135>, Dave <foo@coo.com> wrote:
>> I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
>> is 120 V 400 Hz
>>
>> The specs on the Netra T1 are:
>>
>> 100 - 240 VAC, 47 - 63 Hz, 2 A (max)
>>
>> Has anyone ever tried running one at 400 Hz? My guess is that it is
>> unlikely to be an issue, as the input voltage will soon be converted to
>> DC in the switch mode power supply by a bridge and capacitors. A higher
>> frequency should have not be an issue there, and if anything gives the
>> capacitors an easier time.
>
> Actually the most likely problem would be the bridge. High power diodes
> can be quite slow (have a high stored charge) and can overheat if they
> are run at a high frequency. There are fast diodes available, but they
> cost more and are usually not used if not needed. This is definitely
> a problem in the part of the supply where the switching is done as the
> frequency there is usually over 20000 HZ. I am not sure if 400 HZ is
> high enough to cause problems, but it might be.
> If you try it and blow the bridge, most likely the only other thing that
> will be killed would be a fuse (I assume it does have a fuse). In that
> case the cost of the parts to fix it would not be very high.


I would have thought 400 Hz was pretty slow by semiconductor diode
standards, since the diodes are not going to be very large.

We believe we have solved the problem. We have a 400 -> 50 Hz converter,
but its too small to handle the power we need (it's not just the T1, but
other bits too, totalling about 1 kW). However, we will use that to
power some of the equipment (including the T1) and some other bits,
which we know are speced for 400 Hz will be run from the 400 Hz supply.

* jimp@specsol.spam.sux.com:

> All that depends on how the aircraft itself is certified and under
> which set of rules it is going to fly.

Yes, but in the UK it's not as easy as in the US.

Benjamin

On Jun 13, 9:49 am, Dave <f...@coo.com> wrote:
> I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
> is 120 V 400 Hz
>
> The specs on the Netra T1 are:
>
> 100 - 240 VAC, 47 - 63 Hz, 2 A (max)

Simplest and easiest: http://www.elect-spec.com/freqchgr_a.htm#E

Next: Find a model 100; it had a DC power supply 40->70 VD, 4 A max.
input. Use
a 400 Hz Variac (http://www.elect-spec.com/variac_400.htm) to reduce
the voltage
to the desired level, and rectify to produce the desired input
voltage. If it turns out that
you really have single phase (unlikely), you'll want some caps to
smooth things out.

None of this equipment is air rated, of course... remember that the
T1 is thermally limited
to 10,000 ft elevation during operation.

The odd of the standard AC switching power supply coping w/ 400Hz
input is low.

bart.smaalders@gmail.com wrote:
> On Jun 13, 9:49 am, Dave <f...@coo.com> wrote:
>> I'm looking to use a Sun Netra T1 onboard an aircraft where the supply
>> is 120 V 400 Hz
>>
>> The specs on the Netra T1 are:
>>
>> 100 - 240 VAC, 47 - 63 Hz, 2 A (max)
>
> Simplest and easiest: http://www.elect-spec.com/freqchgr_a.htm#E
>
> Next: Find a model 100; it had a DC power supply 40->70 VD, 4 A max.
> input. Use
> a 400 Hz Variac (http://www.elect-spec.com/variac_400.htm) to reduce
> the voltage
> to the desired level, and rectify to produce the desired input
> voltage. If it turns out that
> you really have single phase (unlikely), you'll want some caps to
> smooth things out.


>
> None of this equipment is air rated, of course... remember that the
> T1 is thermally limited
> to 10,000 ft elevation during operation.

The aircraft will not be flying, so altitude is not an issue.

But that 10,000' feet assumes the only air around is due to the
atmosphere - not an aircraft where there is a continuous supply of air.
So I doubt a T1 would object to flying at 25,000' in the passenger
compartment of an aircraft. (I've certainly used various bits of
lab-grade test equipment and computers in aircraft before while flying
at high altitude, with no ill effects). Put a T1 at 25,000 feet on a
mountain and its a very different matter. But this does not matter here.

> The odd of the standard AC switching power supply coping w/ 400Hz
> input is low.

I guess thinks like zero-volt switching and power factor correction
might be an issue. Personally, if I had to take a guess, I'd say it
would be ok, but I am far from confident of that.

In comp.sys.sun.hardware Benjamin Gawert <bgawert@gmx.de> wrote:
> * jimp@specsol.spam.sux.com:

> > All that depends on how the aircraft itself is certified and under
> > which set of rules it is going to fly.

> Yes, but in the UK it's not as easy as in the US.

True, but so is my statement.


--
Jim Pennino

Remove .spam.sux to reply.

OTOH it will likely handle 160V DC (115V AC bridge rectified) just fine.

One UPS manufacturer is working on DC distribution in computer
centers, which they claim will provide an energy saving of around
20%.

The reason is that you avoid one rectifier and one inverter stage,
plus reduced airconditioning.

Most primary switched PSU:s immediately rectify the AC, so it makes
little sense of taking the DC from the UPS batteries and generate AC,
when you can just as well feed the DC directly to the PSU:s.

They feed 315V DC to the computers, and they had made a major test
involving standard computers with 230V AC switching supplies and they
worked just fine.

I have no idea if they tested Sun PSU:s or not.