current limiter? (beech 1900UC)

splash

splash

your social justice comic center
I am lost in language or time here.

The Aircraft Technical Dictionary (3rd edition) by Jeppesen defines current limiter: A device which limits the generator out put to a level within that rated by the generator manufacturer.

However, the 1900 manual figure 7-1 shows a symbol of a current limiter (or isolation limiter) and also states: this acts as a large, slow blow fuse.

Someone tells me after turning on each generator checking each bus with the overhead rotor dial is called the "current limiter test". Based on my research I'm not sure if I can agree with this. Durring this test I believe you are only checking to see if power is being delivered to the 4 busses, no? Are the current limiters not a part of the GCU? Are these "slow burn" fuses the old way of limiting current? I can't find anything in the manual or the check list that calls this a "current limiter test". Ugh. What is this dude talking about?
 
Slow blow?

ImageUploadedByTapatalk1467487683.511315.jpg
 
They're just big fuses. You pull 1000A across it and continuity is gone. Yes, you're checking that the proper voltage is going to the selected buses. They're not part of the GCU.
 
gotWXdagain said:
Slow blow?

View attachment 35681
Click to expand...

Look now, there is a time and place for everything you primate! Tech talk is not the place nor is this the time to talk about the girl we both knew as "slow blow" from back in high school. I miss her too mayne. You remember as I do, eh? She had the perfect low pitch D flat hum too. OMG...

I'm trying to study here, can't you see, Harry. So how you been old man? We should get together again soon and hang out like we did 2 summers ago. Remember when you got pulled over in your car while you were being goofy wearing that motorcycle helmet with the visor? The cop came to your window, you rolled your window down, and then you lifted up the visor as if this was normal and all...Dude, that was awesome...the cop laughed his ass off. That is the only reason he let us go too! Well cant wait to hang with you again soon Harry.
 
Last edited:
QUOTE="deadstick, post: 2587222, member: 6113"]They're just big fuses. You pull 1000A across it and continuity is gone. Yes, you're checking that the proper voltage is going to the selected buses. They're not part of the GCU.[/QUOTE]

Thanks
 
splash said:
I am lost in language or time here.

The Aircraft Technical Dictionary (3rd edition) by Jeppesen defines current limiter: A device which limits the generator out put to a level within that rated by the generator manufacturer.

However, the 1900 manual figure 7-1 shows a symbol of a current limiter (or isolation limiter) and also states: this acts as a large, slow blow fuse.

Someone tells me after turning on each generator checking each bus with the overhead rotor dial is called the "current limiter test". Based on my research I'm not sure if I can agree with this. Durring this test I believe you are only checking to see if power is being delivered to the 4 busses, no? Are the current limiters not a part of the GCU? Are these "slow burn" fuses the old way of limiting current? I can't find anything in the manual or the check list that calls this a "current limiter test". Ugh. What is this dude talking about?
Click to expand...

The voltage of the busses tells you if power is flowing from the generator to that particular bus or not. Battery voltage indicates a failure of the current limiter on the opposite side. So if you have the right generator on, and the left generator is off, and the right current limiter has blown, well, then right GEN Bus will indicate 28V, the Center Bus and Left Generator Bus will indicate battery voltage. So, the procedure is something like this:

Start the Right Engine
R Gen On
Start the Left Engine
Cycle through the voltages:
Triple Fed Bus should show 27V (because the diode takes out a volt and it's getting Generator Voltage)
the Right GEN Bus should show 28 Volts
The Left GEN Bus and Center Bus should show 28 V, but if they show battery voltage, this indicates a current limiter failure.

Man I miss the 1900...what a cool • airplane.
 
Teach me more...what about the environmental system, in short and simple? Is it P3...ACM....floor vents? What happens if both fail lights come on and is it possible ever? Would ypu slowly lose cabin pressure if both failed?
 
splash said:
I am lost in language or time here.

The Aircraft Technical Dictionary (3rd edition) by Jeppesen defines current limiter: A device which limits the generator out put to a level within that rated by the generator manufacturer.

However, the 1900 manual figure 7-1 shows a symbol of a current limiter (or isolation limiter) and also states: this acts as a large, slow blow fuse.

Someone tells me after turning on each generator checking each bus with the overhead rotor dial is called the "current limiter test". Based on my research I'm not sure if I can agree with this. Durring this test I believe you are only checking to see if power is being delivered to the 4 busses, no? Are the current limiters not a part of the GCU? Are these "slow burn" fuses the old way of limiting current? I can't find anything in the manual or the check list that calls this a "current limiter test". Ugh. What is this dude talking about?
Click to expand...
The current limiter is a device that acts like a fuse. The big ones are generally used to connect yet protect individual parallel sides of an overall electrical system. If one side starts acting froggy and throwing huge load, the limiter will blow out and protect the other side. But it's a fuse that doesn't blow at the rated Amperage. It allows transient instances of over amperage (in fairly large excess of the rated amperage) to pass through the limiter without blowing it out. But every time an over-amperage instance is experienced, the limiter weakens some degree, such that over time the limiter will fail and separate your electrical circuitry. From an operational perspective, everything will generally appear the same with the failed limiter assuming you have only a blow limiter. That is why you have to check it. On the older Lears, for instance, there is no indicator to show if a limiter has blown. Most newer planes having current limiters have check switches in the cockpit to allow you to easily check the continuity of the circuitry.
 
Crop Duster said:
The big ones are generally used to connect yet protect individual parallel sides of an overall electrical system. Most newer planes having current limiters have check switches in the cockpit to allow you to easily check the continuity of the circuitry.
Click to expand...

Individual parallel sides...such as two generators, eh? Ok, I think I got it.

checking the continuity...makes sense, this way you can tell if the current limiter is getting weak.

Now I'm trying to figure out how this will save my ass knowing this all in depth. Now if you lose two or four current limiters then you just a dead duck because now both working generators are now isolated.

Do the one way HED's protect the gen busses or the center bus? I'm getting close to understanding the whole picture.
 
splash said:
Individual parallel sides...such as two generators, eh? Ok, I think I got it.

checking the continuity...makes sense, this way you can tell if the current limiter is getting weak.

Now I'm trying to figure out how this will save my ass knowing this all in depth. Now if you lose two or four current limiters then you just a dead duck because now both working generators are now isolated.

Do the one way HED's protect the gen busses or the center bus? I'm getting close to understanding the whole picture.
Click to expand...
You can't tell the "strength" of the limiter. You can only check that it is passing current and creating the closed circuit. It could still fail at any time after that. You have no idea when it's going to fail other than visual inspection which will tell you "something" but still not anything certain. If you stick your noggin up in the hell hole and see that the physical limiter looks brownish and "burned", it's generally an indication that it will fail soon and needs to be replaced.
 
Crop Duster said:
You can't tell the "strength" of the limiter. You can only check that it is passing current and creating the closed circuit. It could still fail at any time after that. You have no idea when it's going to fail other than visual inspection which will tell you "something" but still not anything certain. If you stick your noggin up in the hell hole and see that the physical limiter looks brownish and "burned", it's generally an indication that it will fail soon and needs to be replaced.
Click to expand...

ok, gotya. Thought you meant an amount of omhs when you wrote checking continuity. I'm not even close to an electrical engineer, I don't know much.
 
Splash
You understand the hall effect detector trips before the triple fed too right?

Old man helped design the electrical sys on the 1900s. He remembered most of it when i flew it a decade ago but i can try jogging his memory if youve got some weird questions.

That dc system is mostly bulletproof. If the triple fed goes you're limited obviously.
 
You must log in or register to reply here.
Back
Top