How much current does modern commercial jet aviaonics draw? In a modern military jet?

[The_Eric]

Was just reading the various threads here talking about weapons systems and avionics which got me wondering - how much power do they draw? Like the entire cockpit suite on a 320, 380, a 47, 57 or 87.

I've also given some thought to the massiveness of the various secret squirrel stuff on a fighter. Like so big that one system may get a sizable chunk of real state dedicated to it when space is always at a premium. Not to mention that it's also doing massive amounts of work.

Obviously only so much can said with respect to fighters, but I'm curious what voltages these things run on and their current draw to better put in perspective how much these things really are doing.

 

[Cujet]

When I'd use ground power on the G550, G650ER or G600 Gulfstream, all modern designs, the load on the power cart display was always lower than expected. Turn on the cabin and things change a bit, as the fridge, window heaters, floor heaters, satcom, internet and other items do use some powa.

Bottom line, the cockpit alone is less than 2000 watts, or more accurately, about 2KVA.
Crank up the cabin and it might reach 5KVA.
Run absolutely everything you can think of, the electric hydraulic pump, radar, pitot heat, window heat, Ka band internet, deep fryer (just kidding) and so on an the number can grow to as much as 25KVA, but that takes deliberate effort.

3ea 40KVA generators. All run in sync, for no-break power transfers between them. 115V. 400HZ.

 

[The_Eric]

When I'd use ground power on the G550, G650ER or G600 Gulfstream, all modern designs, the load on the power cart display was always lower than expected. Turn on the cabin and things change a bit, as the fridge, window heaters, floor heaters, satcom, internet and other items do use some powa.

Bottom line, the cockpit alone is less than 2000 watts, or more accurately, about 2KVA.
Crank up the cabin and it might reach 5KVA.
Run absolutely everything you can think of, the electric hydraulic pump, radar, pitot heat, window heat, Ka band internet, deep fryer (just kidding) and so on an the number can grow to as much as 25KVA, but that takes deliberate effort.

3ea 40KVA generators. All run in sync, for no-break power transfers between them. 115V. 400HZ.

3 generators, each with more than total power requirements? Why is that? A back up to the backup, each with enough overhead to comfortably run the entire system? Also what's up with that frequency? What is gained by running at 400hz?

 

[RooflessVW]

Our H135 draws 30A when the master is switched "on."

3 generators, each with more than total power requirements? Why is that? A back up to the backup, each with enough overhead to comfortably run the entire system? Also what's up with that frequency? What is gained by running at 400hz?

If you run a generator at its max output it will shorten its life. By splitting between three you can increase both service life and redundancy.

400hz for less weight. Smaller components.

 

[97prizm]

Was just reading the various threads here talking about weapons systems and avionics which got me wondering - how much power do they draw? Like the entire cockpit suite on a 320, 380, a 47, 57 or 87.

I've also given some thought to the massiveness of the various secret squirrel stuff on a fighter. Like so big that one system may get a sizable chunk of real state dedicated to it when space is always at a premium. Not to mention that it's also doing massive amounts of work.

Obviously only so much can said with respect to fighters, but I'm curious what voltages these things run on and their current draw to better put in perspective how much these things really are doing.

I do know that an interesting article from one of the aviation blogs specifically mentioned using fuel to cool components on the F-22 and F-35. If this is the case the processing power must be immense.

 

[supton]

What is gained by running at 400hz?

Less iron needed in the transformers for step up/down. Not sure if electric motors can also be made smaller, same principle, but think so.

Higher frequency would start to run into skin depth issues and increased loss in the copper.

 

[The_Eric]

Less iron needed in the transformers for step up/down. Not sure if electric motors can also be made smaller, same principle, but think so.

Higher frequency would start to run into skin depth issues and increased loss in the copper.

Would it be fair to say that you're doing the work 6.66 times faster at a given voltage? 400hz vs 60hz?

Edit: is there a difference in how hot a power source will run at 400 vs 60hz?

 

[supton]

Would it be fair to say that you're doing the work 6.66 times faster at a given voltage? 400hz vs 60hz?

Outside my area but would hazard “no”. Plenty of fixed speed 60hz motors running at multiples of 60hz.

For anything running on dc, I guess the buss capacitance could get smaller, less time between cycles. Might have less peak current? same average power draw though.

Interesting thought: listening to 400hz hum instead of 60hz (or 800 vs 120). Probably can’t hear it, not over the engine.

 

[RooflessVW]

Outside my area but would hazard “no”. Plenty of fixed speed 60hz motors running at multiples of 60hz.

For anything running on dc, I guess the buss capacitance could get smaller, less time between cycles. Might have less peak current? same average power draw though.

Interesting thought: listening to 400hz hum instead of 60hz (or 800 vs 120). Probably can’t hear it, not over the engine.

Another benefit is of 400hz generators is you don't have to gear down as much to spin them.

 

[y_p_w]

Less iron needed in the transformers for step up/down. Not sure if electric motors can also be made smaller, same principle, but think so.

Higher frequency would start to run into skin depth issues and increased loss in the copper.

I wouldn't think it's that big a deal. But skin effect is why a lot of wiring is stranded, in addition to it being more flexible. Here's a skin effect calculator. I'm getting 2 mm at about 1 KHz.

https://www.omnicalculator.com/physics/skin-depth

 

[oil pan 4]

Was just reading the various threads here talking about weapons systems and avionics which got me wondering - how much power do they draw? Like the entire cockpit suite on a 320, 380, a 47, 57 or 87.

I've also given some thought to the massiveness of the various secret squirrel stuff on a fighter. Like so big that one system may get a sizable chunk of real state dedicated to it when space is always at a premium. Not to mention that it's also doing massive amounts of work.

Obviously only so much can said with respect to fighters, but I'm curious what voltages these things run on and their current draw to better put in perspective how much these things really are doing.

Most NATO fighters, helicopters and cargo planes use 400hz 115v.
With fighters how much power they draw greatly depends on if the radar is running or not.

 

[oil pan 4]

I do know that an interesting article from one of the aviation blogs specifically mentioned using fuel to cool components on the F-22 and F-35. If this is the case the processing power must be immense.

It is. I used to work with f22 at Langley.

 

[y_p_w]

A lot of the electronics would be similar to consumer electronics these days - running at fairly low voltage. The power supply might be something standard like 5V, but that voltage has to be stepped down somewhere. A lot of the electronics these days might be field-programmable gate arrays, which can be programmed for their functions. They're not necessarily as compact and efficient as custom chips, but when you're only making a few thousand it doesn't make that much sense to go through all the cost, time, and hassle of custom chips. It also make it much easier to modify.

I have heard one of the issues is that many of these are now using consumer grade FPGAs and other products, where the big problem is that the products are phased out quickly compared to the lifetime of a military product. The US Navy apparently bought a whole bunch of FPGAs as replacement parts for the F-35. But inevitably they're going to have to replace them with newer ones in the future.

 

[supton]

I wouldn't think it's that big a deal. But skin effect is why a lot of wiring is stranded, in addition to it being more flexible. Here's a skin effect calculator. I'm getting 2 mm at about 1 KHz.

https://www.omnicalculator.com/physics/skin-depth

Right, but I was trying to ward off the inevitable "if 60Hz is bad, but 400Hz is better, then why not 1MHz?" Also explains why power lines are 60Hz and not 400Hz, at the high current levels you want all the cross section of a wire to carry current. [Power lines I think use a steel core for strength and the outer layer carries current, think it's aluminum which shows a skin depth of almost 11mm. No need to have the aluminum layer thicker than that, outside of strength or similar reasons.]

 

[y_p_w]

Right, but I was trying to ward off the inevitable "if 60Hz is bad, but 400Hz is better, then why not 1MHz?" Also explains why power lines are 60Hz and not 400Hz, at the high current levels you want all the cross section of a wire to carry current. [Power lines I think use a steel core for strength and the outer layer carries current, think it's aluminum which shows a skin depth of almost 11mm. No need to have the aluminum layer thicker than that, outside of strength or similar reasons.]

I have flashbacks of doing skin effect calculations in my upper division fields & waves class. I think part of the discussion was about how some signals were transmitted through tubing instead of wires, where skin effect was less pronounced since the conductor's cross section was thinner than the skin depth.

 

[supton]

I have flashbacks of doing skin effect calculations in my upper division fields & waves class. I think part of the discussion was about how some signals were transmitted through tubing instead of wires, where skin effect was less pronounced since the conductor's cross section was thinner than the skin depth.

Heliax is used at cell towers I believe; I've ogled it a couple of times when at HRO. Way way waaaay beyond my needs, at just a few MHz, but at several GHz skin depth is just obscenely shallow. But to get loss low... you do tricks like this (before going to waveguides).

Some days I think I went the wrong way in life, loved the theory but never got to use emags in the real world...

 

[MolaKule]

Was just reading the various threads here talking about weapons systems and avionics which got me wondering - how much power do they draw? Like the entire cockpit suite on a 320, 380, a 47, 57 or 87.

I've also given some thought to the massiveness of the various secret squirrel stuff on a fighter. Like so big that one system may get a sizable chunk of real state dedicated to it when space is always at a premium. Not to mention that it's also doing massive amounts of work.

Obviously only so much can said with respect to fighters, but I'm curious what voltages these things run on and their current draw to better put in perspective how much these things really are doing.

See this info;

https://www.powerstream.com/400hz-t...rents and skin-effect increase in resistance.

 

[Cujet]

3 generators, each with more than total power requirements? Why is that? A back up to the backup, each with enough overhead to comfortably run the entire system? Also what's up with that frequency? What is gained by running at 400hz?

Clearly only 1 is needed to power every possible load. That's as it should be.

3 phase, 115V, 400HZ saves a lot of weight, not just at the wiring level, but for contactors and relays, and just about every component that needs to rectify and filter the power to DC. In other words, the entire avionics suite, cabin suite and fly by wire, gear by wire and brake by wire part is considerably smaller and lighter.

If I were to guess, I'd say that this kind of power makes modern planes possible. I clearly recall the "DC" Gulfstream's. The components were huge, heavy and very limited.

 

[y_p_w]

Clearly only 1 is needed to power every possible load. That's as it should be.

3 phase, 115V, 400HZ saves a lot of weight, not just at the wiring level, but for contactors and relays, and just about every component that needs to rectify and filter the power to DC. In other words, the entire avionics suite, cabin suite and fly by wire, gear by wire and brake by wire part is considerably smaller and lighter.

If I were to guess, I'd say that this kind of power makes modern planes possible. I clearly recall the "DC" Gulfstream's. The components were huge, heavy and very limited.

I seem to recall in the 787, they has issues with the batteries catching on fire. But it sounded like they relied on battery power. Not sure about how it was wired or recharged, but I suppose it could reduce the amount of wiring needed to just have the batteries near the control surfaces.

https://www.edn.com/boeing-787-battery-charging-system-solutions-good-design-or-not/