Plane Power Problems

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ghostbuster

ghostbuster

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Went to a major international airport yesterday.

When the passenger planes roll up to the gate and stops,temporary airport power is plugged into the plane.

Power is 200 volts 3 phase 4 wire 400 hz.

A new series of airplanes when plugged in to this power source ,electronically refuse to turn on their loads(note: tested this plane at all gates and will not turn on its loads at any of these approx.30 gates).

At other airports ,these new planes have no problems with the airport power.

At this airport all other plane mfrs, have no problem with this airport power.

Paperwork will need to be resolved before full investigation begins.

Standby :smile:
 
its no big deal. i was just curious. but if this is such a security issue, why did you even start this thread telling us about the problems? if we get hit again, i'm sending the FBI to YOU! :D
 
ghostbuster said:
(note: tested this plane at all gates and will not turn on its loads at any of these approx.30 gates).
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That sounds like a fun job :) Dragging a plane around all the gates in an operating airport...

Are the ground power units of the same model that have been used to supply power satisfactorily elsewhere? Are they gensets, or rotary or semiconductor converters? Do they work on 777 and A340?
 
i'm just guessing here, but i wouldn't think they are taking the aircraft gate to gate. i would think they just had some setup w/ the 'guts' of the power system that is easily transportable.
 
All these units are fixed solid state ,1-2 yrs old,1 unit for each gate.

Similar units are at many other airports.

All major international large airlines land and do not experience power problems at these gates.

Note:neutral return is the plane metallic structure as per the above link dwgs.
 
This is an interesting problem. I briefly read the link and will read in depth later.

What about the equipment grounding conductor requirements? This article seems to stress the importance of it for keeping noise levels low.

here is a partial quote from the article:

*******
" For example, recent noise voltage measurements on a 180kVA frequency inverter found to be missing the system bonding jumper resulted in maximum and minimum voltage measurements of +17.2V and -19.9V. On another poorly bonded system, these measurements yielded a maximum voltage (peak) reading of +3.61V and a minimum reading of -4.36V. After the bonding jumper and fittings on this second system were replaced, the maximum voltage (peak) reading dropped to +0.31V, and the minimum reading dropped to -0.18V. "

********

Could it be that different planes have different sucesptibility to the noise from the inverters?

I wonder how the planes are shutting down? Ground fault, Computer lock up?

I have experience working with EMI issues and this sounds like a possibility.

In a lot of equipment that generates noise, internal EMI protection is dependent upon a good earth ground connection.

I thought I read where the EGC is required for the inverter installation but that it does not travel to the plane through the cable. If I read this correctly and the the connections were wired incorrectly ground loops could also be an issue.
 
Figures 3 and 4 are interesting.
If the neutral is bonded at the generator. And the skin of the plane is the neutral. If the plane skin is then earthed remotely (static bond) doesn't this by it's nature from a ground loop?
If the inverter has a ground fault detector it seems likely for it to trip under the right circumstances. I wonder what the current trip settings on these ground fault detectors are? Are they the same setting on all installations (or adjustable)?

If a ground loop is at issue then some installs may have a problem where others would not depending up on the relative impedances of the neutral conductor used in the cable compared the the impedance of the remote static earth bond. Both the parking stall installation and variations in planes electrical systems would come into play.

this is a very interesting to me ...
 
ELA said:
Figures 3 and 4 are interesting.
If the neutral is bonded at the generator. And the skin of the plane is the neutral. If the plane skin is then earthed remotely (static bond) doesn't this by it's nature from a ground loop?
If the inverter has a ground fault detector it seems likely for it to trip under the right circumstances. I wonder what the current trip settings on these ground fault detectors are? Are they the same setting on all installations (or adjustable)?

If a ground loop is at issue then some installs may have a problem where others would not depending up on the relative impedances of the neutral conductor used in the cable compared the the impedance of the remote static earth bond. Both the parking stall installation and variations in planes electrical systems would come into play.

this is a very interesting to me ...
Click to expand...

According to the info ,we have been told the plane electronics samples the power first and sends back a 28 volt DC signal to close in the main airport gate contactor if the power is found to be "acceptable".

Therefore I don't believe the ground fault circuitry could be a problem at this initial power sampling stage.
 
My money is on Iwire's comment. Although I wouldn't rule out a grounding problem either. If the plane doesn't sense the neutral to ground bond, it may reject the power.

Steve
 
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ghostbuster said:
...the plane electronics samples the power first and sends back a 28 volt DC signal to close in the main airport gate contactor if the power is found to be "acceptable".
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Seems to me in this day and age an electronics system sophisticated enough to sample and accept or reject a power source in the coupling stage would also be sophisticated enough to report by some means why it rejects a source :roll:

...or maybe I watch too many futuristic sci-fi shows :grin:
 
My mom had a Buick like this once - she just left the engine runnin'. ;) Otherwise you needed to jump across the starter relay to get it to crank back up - once a day was enough... :D
 
Need to be a little more exacting here. The plane gets no power until the interlock circuit is completed, and thus the question is has the GPU interlocked contactor closed?

For the interest of others, the modern series of planes, from 777s and A320s on work a bit different than everything before them. Older planes manually changed over from on-board power to ground power exactly the same was as a manual generator changeover switch, so there is a period in the middle of the changeover when there is no power. Thats why the lights go out for a second just before you deplane. The latest planes use something like a static switch to give a no-break changeover. For this to work, I'd have though ground power and plane power would need the same phase sequencing.

So, if the GPU contactor is closed, I'm with IWire - the phase rotation is screwed. If the contactor hasn't closed, then something much odder is going on.
 
dbuckley said:
So, if the GPU contactor is closed, I'm with IWire - the phase rotation is screwed. If the contactor hasn't closed, then something much odder is going on.
Click to expand...

It is my understanding,the A/C(air conditioner) systems on most planes are 3 phase systems.

If the phases were consistently reversed(ie.the wrong direction) on all these 30 gates,I would expect every plane(all MFRS.) would be tripping their A/C breakers during this instant of transfer of power source from plane power to airport power.

This is not happening.

I will try to get more info on the actual main airport power (400 Hz.) breaker interlock system and voltage sampling parameters.
 
ghostbuster said:
If the phases were consistently reversed(ie.the wrong direction) on all these 30 gates,I would expect every plane(all MFRS.) would be tripping their A/C breakers during this instant of transfer of power source from plane power to airport power.
Click to expand...

As a complete WAG, are in fact older planes sensitive to phase rotation? How about the new ones? Is it possible that some planes can adapt and others can't? (For instance, some telephones are polarity sensitive, some aren't.)
 
I'm surprised that you aren't getting an engineer from the ground unit company and an engineer from the plane company to meet on site to determine what's happening. Go to the source of knowledge about this.
 
justdavemamm said:
I'm surprised that you aren't getting an engineer from the ground unit company and an engineer from the plane company to meet on site to determine what's happening. Go to the source of knowledge about this.
Click to expand...

An engineer did show up for the 400 hz. power supply mfr..He had the customer take voltage waveform snapshots of all the power supplies at each gate under load and no-load scenarios(lots and lots of customer manpower was used).That was about 9 months ago;still no action.
 
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