Supernerd Question: Is the electrical system bugged or incomplete?

[Sapper31]

Looking at the Mi-24D manual I have in english, it goes over the bus loading tables (attached relevant tables).

 

Question: if I power the PO750A inverter - this powers the 115VAC inverter bus. Then I can tie this bus to the 115VAC bus with the INV GND TEST SWITCH which should power the 36VAC transformer and everything on the 36VAC main and emergency busses. This doesnt seems to work because I cant get the gyros or ADIs to power.

Also the PT125 inv alone should power the no.2 gyro and ADIs.. so you should in flight be able to switch off the gens, switch on the PT125 inv, and switch to gyro #2 which should give you the ADI and stby AI.. but this doesnt seem to work.

 

Is my info bad or is this not modelled correctly?

[Sapper31]

I may have answered my own question because I think this is a typo in the manual.. it seems the 36VAC 1 phase transformers are powered by the 115VAC busses, not the 36VAC 3phase transformers.. the 3 phase are powered by the generators directly. However, you should still be able to power everything on the 36VAC3P bus with the PT125 inv. 

 

Right now if you are in IMC and get gen fails you're hooped and cant get the gyro/adi back. The PT125 seems to do nothing at the moment.

[XPACT]

I've seen weird electrical system behavior from the day one but I am still waiting for ED to release electrical system schematics like it's done in Mi-8 manual for example or even better if someone has real world Mi-24P manual with electrical system schematics we could easily figure out what the real world behavior should be in every situation possible.

But nevertheless it seems that PT125 is indeed not implemented correctly/bugged out. It will auto engage when generator connected to 208/36V transformer fails but seems to do absolutely nothing to power required systems except for "turning on".

 

EDIT: Oh forgot to mention, I am also pretty sure it shouldn't actually need to power on when only one of the generator fails so that is probably another bug too

Edited March 10, 2022 by XPACT

[Sapper31]

33 minutes ago, XPACT said:

EDIT: Oh forgot to mention, I am also pretty sure it shouldn't actually need to power on when only one of the generator fails so that is probably another bug too

 

Yeah that is my understanding.. each transformer has a main/standby/emergency.. where the emergency ones are the inverters. The PO750A needs to be switched on manually but the PT125 should auto switch on if both the main and standby transformers have failed.

[XPACT]

37 minutes ago, Sapper31 said:

Yeah that is my understanding.. each transformer has a main/standby/emergency.. where the emergency ones are the inverters. The PO750A needs to be switched on manually but the PT125 should auto switch on if both the main and standby transformers have failed.

That is correct for transformer failure.

But I was referring to a situation where for example 36V transformers (main and standby) are fine and are connected to bus A if generator that powers bus A fails it should first trigger bus A and B coupling so now the second working generator is actually powering 36V transformer and other stuff from bus A, PT125 shouldn't engage at that point of course if second generator fails there is sensing circuit for 36V and if absent it should trigger PT125 and also disconnect other non flight essential/high power draw components from 36V bus.

 

Currently in the sim if generator that is connected to the bus where 36V transformers are fails even if the second generator is operational PT125 engages and that 99% shouldn't be the case. 

So basically there is no coupling (and probably load sharing in general) of buses A and B currently, on top of that PT125 doesn't seem to power flight essential systems that it should. 

[Sapper31]

6 hours ago, XPACT said:

in the sim if generator that is connected to the bus where 36V transformers are fails even if the second generator is operational PT125 engages and that 99% shouldn't be the case. 

Not sure the exact breakdown of the gen busses but my understanding is they are parallel and automatically will load all busses onto the good generator in the event of a single gen failure. So you wouldn't even notice a blip because the main transformers never go offline, let alone the standbys. The PT125 shouldnt even be remotely involved in a single gen fail. I havent noticed this kicking on but then again I havent really looked.. most of my gen fails are from drooping.