Q of Electrical system. What the manual says confuse me...

[prime_max]

Hi guys. there are something I can't understand about electrical system.

 

Manual 13-20 (Emergency AC Power Supply) says:

In case of main AC system failure, the AC consumers will be supplied by the static POS-500B inverter. This will transform the 27V DC of the batteries into 115V AC.

The POS-500B inverter supplies the following consumers connected to the emergency bus:

 Radar altimeter

 Power plant‟s oil pressure switches

 Fuel quantity indicator, G-load accelerometer, engines RPM and EGT indicators, and vibrations monitoring system

 IFF equipment

 Warning and indications systems

 Audio tones for rotor RPM drop

 Emergency instrument panels illumination

 

but 13-21 (DC system):

The following power consumers are supplied by the DC emergency buses (in case both generators and rectifiers fail):

 POS-500B inverter to supply the AC consumers

 Communication equipment: VHF radios, intercom

 Radar altimeter

 IFF responder

Weapon control system

 Power plant and hydraulic system indicators

 Fuel quantity indicator, fuel pumps, and shut-off valves

 PTS-25 inverter to supply the standby horizon

 Lights

 Pitot heating

 Warning and indication systems and EKRAN system

 

What confuse me is why some equipments(radar altimeter, fuel quantity indicator,etc) are supplied by AC and DC emergency system both?

 

and in the game when I cut two AC generators and two batteries, I saw that radar altimeter,G-accelerometer and RPM indicators and so on were still running. Why?

 

what equipments are on the DC reserve bus and AC reserve bus?

 

I'm really looking forward to answers.:helpsmilie:

[Griffin]

In case of main AC system failure, the AC consumers will be supplied by the static POS-500B inverter. This will transform the 27V DC of the batteries into 115V AC.

POS-500B inverter to supply the AC consumers

 

The emergency bus is only DC. The inverter connected to the DC bus is what powers some of the AC equipment on the emergency DC bus. The radar altimeter, fuel quantity indicator etc use AC from the inverter.

Sorry for multiple edits. I'm not really thinking straight right now. I slept only 3 hours last night.

Edited February 18, 2013 by Griffin

[JG14_Smil]

Manual says a lot that doesn't really mean anything in the sim.

[prime_max]

Manual says a lot that doesn't really mean anything in the sim.

 

So which is real?

[Griffin]

What doesn't add up?

[prime_max]

The emergency bus is only DC. The inverter connected to the DC bus is what powers some of the AC equipment on the emergency DC bus. The radar altimeter, fuel quantity indicator etc use AC from the inverter.

Sorry for multiple edits. I'm not really thinking straight right now. I slept only 3 hours last night.

 

But the electrical system diagram says that the inverter is connected to two AC reserve BUS. I can't understand that some AC equipments is on the DC bus.

 

thank you anyway guy.

[Griffin]

It's all correct as far as I can see. The AC equipment you are talking about are normally fed by and AC system when the generators are feeding them. When they fail or you switch them off, some of the vital systems you listed will now be fed with AC by the inverter. The inverter in turn is fed by the DC system and uses it to transform DC to AC. It sort of interconnects the two systems for those equipment you listed but is only operational when the generators are NOT. :)

I hope I make sense.

 

PS. There are no stupid questions. Feel free to ask more! This does mean alot in the sim and should work as advertised. As long as you keep the inverter switch in the "auto" position, you don't have to worry about it.

Edited February 18, 2013 by Griffin

[prime_max]

It's all correct as far as I can see. The AC equipment you are talking about are normally fed by and AC system when the generators are feeding them. When they fail or you switch them off, some of the vital systems you listed will now be fed with AC by the inverter. The inverter in turn is fed by the DC system and uses it to transform DC to AC. It sort of interconnects the two systems for those equipment you listed but is only operational when the generators are NOT. :)

I hope I make sense.

 

PS. There are no stupid questions. Feel free to ask more! This does mean alot in the sim and should work as advertised. As long as you keep the inverter switch in the "auto" position, you don't have to worry about it.

 

Yes,what you said is right guy.But I think I should express my confusions more clear.

 

In the game,When I cut two AC generators with the inverter ON,I noticed that Radar altimeter and Fuel quantity indicator is working because they were fed by AC reserve Bus,just as what manual 13-20 says .And then I turned the inverter OFF.AC reserve Buses were unpowered,but The DC emergency Buses were still fed.Then I saw that Radar altimeter and Fuel quantity indicator weren't running ,which is strange because accroding to manual 13-21 the two equipments can be also fed by The DC emergency Bus!

 

I misunderstand the manual?

Edited February 18, 2013 by prime_max

[seikdel]

Do they perhaps require both AC and DC power?

[Griffin]

The emergency DC bus feeds the inverter, not the Ralt or FQI directly. If you turn the inverter off, it will not feed the Ralt or FQI. The inverter is the only link from emergency DC bus to the AC equipment if the generators are off.

 

The inverter switch is the key here. If you look at the electrical schematic, it does exactly what is said in the description. However the 13-21 part might be misleading because it lists the equipment we are talking about as if all of them operate on DC power. You are right in that part.

I would explain the DC emergency bus first and remove all the equipment from the list fed by the inverter and only after that list what the inverter feeds.

 

Seikdel; I doubt it. The 13-21 lists equipment that is fed by the inverter and the inverter itself which creates confusion. I might be missing something obvious though. :D I haven't really slept.

Edited February 18, 2013 by Griffin

[prime_max]

The emergency DC bus feeds the inverter, not the Ralt or FQI directly. If you turn the inverter off, it will not feed the Ralt or FQI. The inverter is the only link from emergency DC bus to the AC equipment if the generators are off.

 

The inverter switch is the key here. If you look at the electrical schematic, it does exactly what is said in the description. However the 13-21 part might be misleading because it lists the equipment we are talking about as if all of them operate on DC power. You are right in that part.

I would explain the DC emergency bus first and remove all the equipment from the list fed by the inverter and only after that list what the inverter feeds.

 

Seikdel; I doubt it. The 13-21 lists equipment that is fed by the inverter and the inverter itself which creates confusion. I might be missing something obvious though. :D I haven't really slept.

 

Do you mean 13-21 list includes 13-20 list?

 

Have a sweet dream tonight guy;)

[Griffin]

I would put it this way. It's always possible that I'm wrong but this makes a lot more sense to me. :)

The following power consumers are supplied by the DC emergency buses (in case both generators and rectifiers fail):

 POS-500B inverter to supply the AC consumers (see list below)

 Communication equipment: VHF radios, intercom

 Weapon control system

 Power plant and hydraulic system indicators

 Fuel pumps, and shut-off valves

 PTS-25 inverter to supply the standby horizon

 Lights

 Pitot heating

 EKRAN system

 

In case of main AC system failure, the AC consumers will be supplied by the static POS-500B inverter. This will transform the 27V DC of the batteries into 115V AC.

The POS-500B inverter supplies the following consumers connected to the emergency bus:

 Radar altimeter

 Power plant‟s oil pressure switches

 Fuel quantity indicator, G-load accelerometer, engines RPM and EGT indicators, and vibrations monitoring system

 IFF equipment

 Warning and indications systems

 Audio tones for rotor RPM drop

 Emergency instrument panels illumination

[dahui]

In the RealWorld Helicopters, which i know, (Jetranger, Lama and Hughes 300) you dont need Electrical Power for the RPM and Torque Indicators...

[prime_max]

It still confuse me and What about EEG? Is it supplied by batteries?

[-MadCat-]

In fact the manual is wrong on more than just one thing regarding the electrical system (and confusing too).

 

There are 3 sources or "requirements" of power:

27V DC, 115V AC and 200V AC.

 

The batteries can provide 27V DC directly and 115V AC via the POS-500B inverter (emergency bus).

 

Only the generators can provide 200V AC and when online provide also 115V AC, and 27V DC via the two VU-6B rectifiers.

If the inverter switch is in AUTO, the POS-500B inverter is disconnected once the generators are connected to the electrical circuits.

 

Generators are the primary source of electrical power, batteries remain switched on as a means of backup if both generators fail.

Until that happens, the batteries are not feeding power to any system and should receive charging by the generators.

 

If your generators are malfunctioning or switched off, say goodbye to everything needing 200V AC.

That is just for a few examples, entire weapons system, L-140 LWR, UV-26 CMS, and some more.

The batteries will then provide power to all 27V DC and 115V AC systems (during flight, that is considered an emergency condition).

 

Some stuff works without any power at all:

G-meter, rotor rpm, engines rpm, fuel cut-off valves.

Maybe more but those are the ones I remember right out of my head.

 

The manual, as you see and already noticed, is somewhat dated and wrong on some things (or the sim is wrong and manual is right, don't know).

 

 

Towards the questions:

 

The EEG are powered by 27V DC, either by the batteries or the generators if they are running and connected

(don't know if that's correct, but that's what I experienced).

 

Radar altimeter and fuel quantity indicator require 115V AC, by the battery via the inverter (27V DC converted to 115V AC)

or by the generators directly.

 

The engine rpm gauge doesn't require power (speed sensor usually mounted at the engine's accessory gearbox in combination with a moving coil instrument).

 

 

Greetings

MadCat

Edited September 28, 2014 by -=MadCat=-

[prime_max]

Thank you very much,Madcat.I think the correct answer will be a mystery for us forever since we can't get the manual for a real shark.

[Raptor9]

I'm just shooting in the dark here, but it may be possible that some subcomponents of a system require different power systems. For example, maybe the radar altimeter gauge in the cockpit uses DC, but the actual radar altimeter transmit and receive antennas on the bottom of the aircraft use AC power.

 

Again, just speculating.