Inverter light keeps turning On

[doc_kf3ina]

Hi

 

I'm flying the kh-50 since not so long ago and so far I haven't got any major problems, except that the Inverter On light on the overhead right panel comes up sometimes in the middle of a flight. At the same time some systems seem to turn off (for example the UV-26 countermeasures system). I don't know if this is normal or not (it's a green light after all :smilewink:) but it keeps bugging me, and I have read the manual top to bottom with no luck :book:.

 

Thanks to everyone

[Zembla]

Hi

 

I'm flying the kh-50 since not so long ago and so far I haven't got any major problems, except that the Inverter On light on the overhead right panel comes up sometimes in the middle of a flight. At the same time some systems seem to turn off (for example the UV-26 countermeasures system). I don't know if this is normal or not (it's a green light after all :smilewink:) but it keeps bugging me, and I have read the manual top to bottom with no luck :book:.

 

Thanks to everyone

 

 

Considering the UV-26 will not come on until you've spooled up both engines, and flipped the AC generator switches, I'm assuming that when the inverter cuts out the UV system will not receive enough juice, and thus will also cut out.

 

I'm assuming the AC generators are asynchronic engines? I'm assuming the converter converts the AC to DC so that it can be used by onboard systems? Considering systems like f.ex. the UV-26 don't really need the advantages of AC, they probably operate on DC...

 

Then again, I'm no expert, but I know of a few on this forum who are. So I'm sure that if I 'm wrong they'll correct me :p

 

-Z

[BakaNi]

Sounds like rotor rpm is dropping below the minimum speed needed to turn the ac generators.

 

You're either overloaded or trying to push the chopper too hard. Is the engine limit warning light, lit?

 

EDIT: I'm assuming you've got the throttles in the correct position (AUTO - page up twice if on cold start)

[AlphaInfinity]

Sounds like rotor rpm is dropping below the minimum speed needed to turn the ac generators.

 

You're either overloaded or trying to push the chopper too hard. Is the engine limit warning light, lit?

 

EDIT: I'm assuming you've got the throttles in the correct position (AUTO - page up twice if on cold start)

 

 

He is correct, the engine RPM's are dropping below the minimum

[doc_kf3ina]

You're either overloaded or trying to push the chopper too hard. Is the engine limit warning light, lit?

 

EDIT: I'm assuming you've got the throttles in the correct position (AUTO - page up twice if on cold start)

The engine limit warnings don't lit. I think it's the opposite, when rpm's drop too low it's when the inverter on lights come up, like AlphaInfinity said. But then two other questions come to me:

 

First, it's an inverter so it converts DC current into AC (maybe I'm wrong, Zemba, but I think you're mixing an inverter with a converter) so when it comes ON it should provide whatever electricity is necessary for the systems (and here I'm with Zebla, I think the UV-26 probably runs on DC too).

 

And second, does this happen to anyone too?? Because it's pretty annoying when you're busy dodging some TOW and the contermeasures system goes out. Any ideas or solutions to this?

 

Thanks again for the insights and please pardon my english :thumbup:

Edited March 3, 2009 by doc_kf3ina

[JDski]

I believe what they are saying is that your overloading the engine by possibly giving too much collective. This sudden load lowers the RPM's and causes the generators to not put out enough juice for your systems to work. It also causes your inverter light to come on.

[AlphaOneSix]

Your Inverter switch is normally set to AUTO. Since the switch is in the AUTO position by default, most people overlook it. In AUTO, the inverter comes on to provide some (not all) AC-powered systems with AC power. (As mentioned previously, the inverter takes DC power as an input, and outputs AC power). You will notice that during startup, before your AC generators are online, the INVERTER ON light is lit. Once your AC generators are online, the inverter shuts off automatically (it's in the AUTO position, remember?) and all AC power is provided by the AC generators. When your rotor RPM drops too low, your AC generators will automatically drop offline (they also come back online automatically once rotor RPM increases). When your AC generators drop offline, your inverter comes on again automatically (assuming the inverter switch is in AUTO and not OFF) and provides some of your AC-powered systems with AC power. I don't remember which systems off the top of my head, but I know that you don't get your 200 volt power, only 115 volt. So anything powered by 115VAC will continue to work on battery power through the inverter, while anything that requires 200VAC will stop working. Also, anything powered by 28VDC will also continue to work, at least until your batteries die (which I can't remember if that's modeled or not).

[Slayer]

I never understood this either. In most DC systems the generators power the inverter which in turn charges the batteries and powers DC components. If the engine loads up and the generator can't produce enough power your batteries should have enough reserve to overcome this. I just can see how the batteries would draw down that fast if the low RPM condition only lasts for a few seconds, after all when you start your engines on battery power and that takes way longer than a few seconds to crank the engines. As long as the battery switches are on would they still not be in the circut? The only thing I can think of is that somehow the batteries are not wired in paralell with the DC system...

 

In my mind this would be similar to towing a heavy load in your car and having the stereo and lights cutting out after only a few seconds...

[Frederf]

The batteries provide DC, not 400hz AC, and thus aren't meaningful at all to AC power requirements.

[doc_kf3ina]

I never understood this either. In most DC systems the generators power the inverter which in turn charges the batteries and powers DC components. If the engine loads up and the generator can't produce enough power your batteries should have enough reserve to overcome this. [...]

 

In my mind this would be similar to towing a heavy load in your car and having the stereo and lights cutting out after only a few seconds...

 

EXACTLY what's in my mind :P.

 

The batteries provide DC, not 400hz AC, and thus aren't meaningful at all to AC power requirements.

 

True, but that's why the inverter comes in, doesn't it?

 

I believe what they are saying is that your overloading the engine by possibly giving too much collective.

 

Ok, I understand that now. But is there any limiter to be established that won't permit the engine's rpm's to drop too low? Or it's just that I've to be more careful with the collective when maneuvering?

Edited March 3, 2009 by doc_kf3ina

[sobek]

IIf the engine loads up and the generator can't produce enough power your batteries should have enough reserve to overcome this. I just can see how the batteries would draw down that fast if the low RPM condition only lasts for a few seconds, after all when you start your engines on battery power and that takes way longer than a few seconds to crank the engines.

 

As any other source of voltage, batteries have a maximum load, if you exceed that, the voltage supplied by the battery will drop (not associated with the batterie being completely discharged), it can also result in catastrophic battery failure (namely the battery exploding due to the acid starting to boil because of high temperatures associated with overload, also depending on the type of battery, but they are all not happy with overload). Given that batteries of a load class that could supply all systems with power would be very heavy, i suppose the engineers opted to power only systems that are necessary for startup. Also, it seems, as AO6 has stated, that the inverter supplies only 115V AC and some systems need 200V AC.

 

That is also why you have an APU in your helicopter, because the batteries would not be able to supply sufficient power to crank an engine.

Edited March 3, 2009 by sobek

[DiabloSP]

Thanks AlphaOneSix, very interesting and insightful explanation. Now it all makes sense to me.

[JDski]

Quote:

Originally Posted by JDski

I believe what they are saying is that your overloading the engine by possibly giving too much collective.

 

Ok, I understand that now. But is there any limiter to be established that won't permit the engine's rpm's to drop too low? Or it's just that I've to be more careful with the collective when maneuvering?

 

You have auto throttle (the center detent), but once the maximum throttle is reached, that's it.

Edited March 3, 2009 by JDski