Van's Air Force
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Master turned off
- Thread starter Ron B.
- Start date
Does the master switch also control the alternator? If it does, then I agree with Butch. If the master switch does not control the alternator, and the alternator remains turned on, then the alternator will supply power while the battery is disconnected. In that case, everything will remain on. However, the voltage is likely to be unstable without a battery connected. It is probably best not to shut off the master switch in flight without a good reason for doing so.
My buddy had a high voltage warning on his EFIS and he turned most everything on to see if it would stabilize but it did not so he turned the master off. He waited about 30 seconds and with everything still in the on position turned the master back on. Immediately the CO detector blew sparks out from the front and everything went black (or stayed black) . The only breaker that popped was the strobes. We are not sure if he had an over voltage and this is what caused his issues now or if turning the master off and back on again with all circuits on is causing his problem now. The master disconnects the alt. feed as well.
I'm wandering if turning on the master with all circuits on would allow a burst of energy to all components damaging them before the battery could even things out?
He removed his 396 GPS from the aircraft and it would then power up on it's own battery.
I plan on visiting his aircraft tomorrow and try and trouble shoot some for him.
Thanks
I'm wandering if turning on the master with all circuits on would allow a burst of energy to all components damaging them before the battery could even things out?
He removed his 396 GPS from the aircraft and it would then power up on it's own battery.
I plan on visiting his aircraft tomorrow and try and trouble shoot some for him.
Thanks
flytoboat
Well Known Member
Here's my story...
Took off one afternoon for a short refueling flight. As I turned out of the pattern, I got a high voltage alarm on my GRT EIS, 15V. I've had this happen before and would turn off the alternator field switch for a few seconds then reset. This time, I accidentally hit the master switch instead of the alt field switch. I was surprised to see everything go blank and realized what happened. I reset the master switch and was surprised again that not everything came back online. Turned back to the airport and landed uneventfully until the engine RPM got below 900 RPM and the engine died (P-mags). Everything that was powered on at the time was damaged except for the EIS and the Garmin GTR200. What was damaged: GRT mini EFIS, Trigg TT22, both P-mags, all LED lighting (nav, strobe, landing), iPad, in-dash USB power port.
All companies were great to deal with and repaired/replaced all items that were damaged. An expensive lesson to say the least. I replaced my master switch with one that will disconnect the alternator before disconnecting the battery and also one that you have to pull out on the toggle before changing it's position.
In researching what happened, I found that if you remove the battery from an alternator that is producing output, it can cause voltage spikes of several hundred volts. Without the battery connected to absorb the spike, most equipment that was powered on took the hit. I believe this is what happened to me.
Took off one afternoon for a short refueling flight. As I turned out of the pattern, I got a high voltage alarm on my GRT EIS, 15V. I've had this happen before and would turn off the alternator field switch for a few seconds then reset. This time, I accidentally hit the master switch instead of the alt field switch. I was surprised to see everything go blank and realized what happened. I reset the master switch and was surprised again that not everything came back online. Turned back to the airport and landed uneventfully until the engine RPM got below 900 RPM and the engine died (P-mags). Everything that was powered on at the time was damaged except for the EIS and the Garmin GTR200. What was damaged: GRT mini EFIS, Trigg TT22, both P-mags, all LED lighting (nav, strobe, landing), iPad, in-dash USB power port.
All companies were great to deal with and repaired/replaced all items that were damaged. An expensive lesson to say the least. I replaced my master switch with one that will disconnect the alternator before disconnecting the battery and also one that you have to pull out on the toggle before changing it's position.
In researching what happened, I found that if you remove the battery from an alternator that is producing output, it can cause voltage spikes of several hundred volts. Without the battery connected to absorb the spike, most equipment that was powered on took the hit. I believe this is what happened to me.
The only times I've removed power from the system in-flight, I took the alternator off-line first, then reduced RPMs to a very low level, cycled the master, then brought the alternator back on-line and then powered back up.
That seemed fine, but it's not something I want to do unless really necessary (this was a balky transponder and I was about to enter Class B airspace).
That seemed fine, but it's not something I want to do unless really necessary (this was a balky transponder and I was about to enter Class B airspace).
flytoboat
Well Known Member
The rest of the story.
When this occurred, I was using a Nipon Denso IR alternator. I removed it and took it to NAPA to have it tested. It was putting out 11.5 volts, so it was damaged too. I replaced it with a Plane Power IR alternator. While checking out the Alternator Field circuit, I found a bad splice in the wire under the panel. The bad splice caused the sense voltage to increase the alternator output voltage. The voltage in flight, never got above about 16 volts (per the EIS) which should cause no harm in the short term. Disconnecting the battery from a hard working alternator is what I believe caused the damage - not turning the master back on. The damage was already done. The Aeroelectric Connection explains the damage caused by removing a battery from the alternator. I have replaced the master switch with one that prevents this from happening again.
When this occurred, I was using a Nipon Denso IR alternator. I removed it and took it to NAPA to have it tested. It was putting out 11.5 volts, so it was damaged too. I replaced it with a Plane Power IR alternator. While checking out the Alternator Field circuit, I found a bad splice in the wire under the panel. The bad splice caused the sense voltage to increase the alternator output voltage. The voltage in flight, never got above about 16 volts (per the EIS) which should cause no harm in the short term. Disconnecting the battery from a hard working alternator is what I believe caused the damage - not turning the master back on. The damage was already done. The Aeroelectric Connection explains the damage caused by removing a battery from the alternator. I have replaced the master switch with one that prevents this from happening again.
Carl Froehlich
Well Known Member
I strongly recommend no design or inadvertent switch setup that would allow the alternator to be connected to any buss without a battery. I note there are some aftermarket power control boxes that do this so be careful on what you install. When an alternator fails high, the battery is what provides the sump for the excess power to give the pilot a few moments to take action before the panel gets fried. Note that special precaution are needed for EarthX type batteries that protect themselves on high voltage by going off line - here assume the alternator over voltage protection does not work, or works late (as has happen to me). What would happen in your ship?
On all three of my RVs and two others flying the POH specifies the first immediate action for any electrical issue is to open both master solenoids (one for each battery). This isolates the most common problems and places the system in it?s most reliable configuration, each battery feeding half of the panel. After that the pilot can take his time to figure out what is going on, or just continue IFR capable flight for 2+ hours and figure it out on the ground.
Carl
On all three of my RVs and two others flying the POH specifies the first immediate action for any electrical issue is to open both master solenoids (one for each battery). This isolates the most common problems and places the system in it?s most reliable configuration, each battery feeding half of the panel. After that the pilot can take his time to figure out what is going on, or just continue IFR capable flight for 2+ hours and figure it out on the ground.
Carl
PilotjohnS
Well Known Member
Don,
Sorry to hear about your experience. Would I be correct to assume you have an internal voltage regulator in your alternator, like a Plane Power or similar?
shamer
Well Known Member
Master switch
I don?t remember the switch designation but it?s a three position switch. The lower position is off, middle position is Master and the top position is the alternator. The alternator always goes off line first. It?s in Bob Knuckols book. I?m not home so can?t provide more detail.
I don?t remember the switch designation but it?s a three position switch. The lower position is off, middle position is Master and the top position is the alternator. The alternator always goes off line first. It?s in Bob Knuckols book. I?m not home so can?t provide more detail.
rv7charlie
Well Known Member
I don't doubt the damage detailed in the past few posts, but baseline info is limited or missing, and analysis of the causes (meaning what actually happened to cause the damage) seems less than perfect.
Some older IR alternators (including models that have been commonly used in homebuilts), if subjected to 'load dump' (like switching off the master while the alternator is under significant load), can have their internal regulator destroyed by the voltage spike. That failure can be either benign (no output), or hazardous (overvoltage).
1st mistake in all cases would likely be: no overvoltage protection.
General bad thought process, partly driven by troubleshooting while we should be flying: having your monitor warn you of overvoltage, and then doing a load dump (?) (turning off everything *but* the alternator), and *then*, reconnecting all those expensive devices to an alternator that you were warned had a problem (???).
While a lead-acid battery will moderate and delay the damage from an OV event, if you disconnect everything including the battery and then reconnect everything, even if you include the battery, the voltage (not a spike; steady state voltage) could well be close to 100V when you repower everything. There's a pretty good chance you'll fry some (all?) stuff before the battery can drag voltage back down to sub-20V levels.
edit: Should have mentioned, many of these older IR alternators, once 'turned on' via their "I" terminal, never stop their output until they stop spinning. So if you switch off the master, even if the alternator is disconnected from the bus it's still making output. Not a big deal *if* the operator understands how it works and the ramifications. But if there's an OV event and no way to open the B-lead fat wire from the alternator (an OV protection relay), then if the bus is powered back up, it'll see the max output from the failed alternator, which can be 100V or more.
With a Brand E.X. battery, you better be absolutely sure you have functioning OV protection, because if the EX decides to take a hike (justified or not), you're almost certain to get a large voltage swing out of *any* alternator that doesn't have OV protection running interference between it & the loads.
Minor tweak to the statement about AEC & removing the battery from the alternator: It's not removing the battery, per se; it's removing *the load*, part of which which may be the battery. But if you've been flying very long, the load is more likely to consist of the normal electrical loads. Once recharged (taking only a few minutes at cruise rpms), the battery is largely just along for the ride. After that point, you could remove/replace the battery terminal at will, and likely never notice that you'd done it, unless you're monitoring an oscilloscope on the alternator output while doing it. You *might* hear a little extra hum or whine in your intercom. (You'd see a max of about 1V of 'ripple' on the DC output of the alternator; far less than the change you get in voltage if the alternator just died, where you'd see an instant drop from 14+V to 12V and falling.) Do understand the difference(s) between disconnecting a battery and turning off the master.
Charlie
Some older IR alternators (including models that have been commonly used in homebuilts), if subjected to 'load dump' (like switching off the master while the alternator is under significant load), can have their internal regulator destroyed by the voltage spike. That failure can be either benign (no output), or hazardous (overvoltage).
1st mistake in all cases would likely be: no overvoltage protection.
General bad thought process, partly driven by troubleshooting while we should be flying: having your monitor warn you of overvoltage, and then doing a load dump (?) (turning off everything *but* the alternator), and *then*, reconnecting all those expensive devices to an alternator that you were warned had a problem (???).
While a lead-acid battery will moderate and delay the damage from an OV event, if you disconnect everything including the battery and then reconnect everything, even if you include the battery, the voltage (not a spike; steady state voltage) could well be close to 100V when you repower everything. There's a pretty good chance you'll fry some (all?) stuff before the battery can drag voltage back down to sub-20V levels.
edit: Should have mentioned, many of these older IR alternators, once 'turned on' via their "I" terminal, never stop their output until they stop spinning. So if you switch off the master, even if the alternator is disconnected from the bus it's still making output. Not a big deal *if* the operator understands how it works and the ramifications. But if there's an OV event and no way to open the B-lead fat wire from the alternator (an OV protection relay), then if the bus is powered back up, it'll see the max output from the failed alternator, which can be 100V or more.
With a Brand E.X. battery, you better be absolutely sure you have functioning OV protection, because if the EX decides to take a hike (justified or not), you're almost certain to get a large voltage swing out of *any* alternator that doesn't have OV protection running interference between it & the loads.
Minor tweak to the statement about AEC & removing the battery from the alternator: It's not removing the battery, per se; it's removing *the load*, part of which which may be the battery. But if you've been flying very long, the load is more likely to consist of the normal electrical loads. Once recharged (taking only a few minutes at cruise rpms), the battery is largely just along for the ride. After that point, you could remove/replace the battery terminal at will, and likely never notice that you'd done it, unless you're monitoring an oscilloscope on the alternator output while doing it. You *might* hear a little extra hum or whine in your intercom. (You'd see a max of about 1V of 'ripple' on the DC output of the alternator; far less than the change you get in voltage if the alternator just died, where you'd see an instant drop from 14+V to 12V and falling.) Do understand the difference(s) between disconnecting a battery and turning off the master.
Charlie
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rv7charlie
Well Known Member
Here's the link to the whole book:
http://www.aeroelectric.com/Book/AEC_R12A.pdf
Worth your time, and you can't beat the price...
flytoboat
Well Known Member
I bought this switch from Seinair:
https://www.steinair.com/wp-content/uploads/2016/03/LT-003-Typical-use-as-MASTER-sw.pdf
That config is referred to as a SP3T switch, but requires a jumper wire to achieve that effect. It is useful for unique applications like what you refer to. I have a few on my 10
Walt
Well Known Member
DPDT 3 pos, No jumper req'd as a mstr/alt switch.
Honeywell 2TL1-10A is my switch of choice.
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Walt, I'm finding 2TL1-10A but not exactly the P/N you quoted. Is this the same as you use?
Mark33
Well Known Member
2TL1-10 is an on/on/on switch. Do you want it to have a lockout in one of the positions or maybe a momentary position? If so, let me know what position you’d like to have lock out or momentary and I can provide you with that particular part number. Honeywell makes ten different 2TL1 three position switches and the “dash” after “1” determines the configuration of the switch. As an example, the 2TL1-50 is an on/on/(on) switch where it is momentary in one of the extreme positions.
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rv7charlie
Well Known Member
Just posted an edit with more info in post #15.
Charlie
Charlie
Walt
Well Known Member
Yea sorry, 2TL1-10A (edited previous post)
Mark33
Well Known Member
So I guess he?s looking for one that?s locked out in all three positions??... with the ?A? designation.
Walt
Well Known Member
Just a suggestion, that's just what I use, makes a good master switch IMO with 3 distinct positions. Use whatever you prefer.
APEM 3way locked pos switch
I used the APEM switch, locked in all 3 positions with the same function as the Honeywell variant. APEM is used in the TBM aircraft for example. It's a high quality switch and the lever is slightly smaller compared to Honeywell. Also a bit cheaper..
PM me if interested.
I used the APEM switch, locked in all 3 positions with the same function as the Honeywell variant. APEM is used in the TBM aircraft for example. It's a high quality switch and the lever is slightly smaller compared to Honeywell. Also a bit cheaper..
PM me if interested.
I think I'm going to go with the one Walt suggested. Should suit our needs.
I'm having a very hard time finding a suitable key switch. I received a switch that was just what I thought I needed but it had no detent in the positions. The key could very easily be rotated from off to on or the other way round. I'm just looking for a SPST on -off key switch with position detents so it stays where I select it to be. It doesn't need to start anything, just energies my master solenoid . I want to be able to remove the key for a little security. Any help with a part number for such a bird would also be much appreciated.
Thanks to all Ron
I'm having a very hard time finding a suitable key switch. I received a switch that was just what I thought I needed but it had no detent in the positions. The key could very easily be rotated from off to on or the other way round. I'm just looking for a SPST on -off key switch with position detents so it stays where I select it to be. It doesn't need to start anything, just energies my master solenoid . I want to be able to remove the key for a little security. Any help with a part number for such a bird would also be much appreciated.
Thanks to all Ron
This is the three position, progressive throw, Honeywell locking toggle from Steinair which people are alluding too. I've found it excellent. No jumper wiring is needed.
Down is "all power off". Middle position is "battery only". Top position is "battery + alternator". Requires a very deliberate action to power on or off, and it is not possible (nor desirable) to run the alternator without the battery already being on.
Down is "all power off". Middle position is "battery only". Top position is "battery + alternator". Requires a very deliberate action to power on or off, and it is not possible (nor desirable) to run the alternator without the battery already being on.
Mark33
Well Known Member
Ron,
If all you?re looking for is a two position ON/OFF switch with a lockout to prevent you from inadvertently turning it off...basically just a key switch, the 2TL1-3F or 2TL1-3G will do the trick. The only differences in these two switches is whether the lockout is on the key-way or opposite key-way side. Sometimes one or the other will be easier to find and a little cheaper...but they function exactly the same. This switch will allow you to just flip it up...without having to pull the lever out first to move it into the ON position, but then it?ll be locked into the ON position, which will then require you to pull the lever out to put it back into the OFF position.
If you?d like to get rid of whatever separate momentary start button you have and combine your master and start functions into one switch, then I?d recommend the 2TL1-50N....ON/ON/(ON). This switch will allow you to just flip it up into middle (master ON position) then momentary up into the (start position). You will be locked out of the OFF position and will require you to pull the lever out to put it back into the OFF position. This is the switch that I have in my airplane and it prevents me from inadvertently turning it off. It?s very simple and reliable and let?s me combine two switches into one.
rv7charlie
Well Known Member
Mark,
I think he's looking for a switch with an actual key (as in, security lock; not a switch with a keyway), that has a detent in both positions, to prevent inadvertent movement while the key is inserted.
With your switch, when you move it from <off> to <on>, is there a latching detent to prevent it's movement through <on> to <start>, in one motion?
Carl Froehlich
Well Known Member
I recommend not doing this. The ease of inadvertently engaging the starter motor to crank the engine when you only want to turn on the master is an unnecessary risk.
Keep the starter push button.
Carl
Mark33
Well Known Member
Charlie,
It?s momentary in the third (start) position, so yes, you could go from OFF, to ON, to (START), all in one motion. The lockout is to prevent me from inadvertently moving the switch back into the OFF position which would disconnect the master and the alternator B lead. ***I do however have a separate alternator field switch. So, once it?s flipped on, the only position that it can be moved into, without pulling the lever out, is the momentary (start) position. Once again, the lockout is to prevent me from accidentally moving it back into the OFF position. The switch that I?m talking about has a pretty heavy spring in the momentary (start) position, so it?s pretty unlikely that I would accidentally engage it and bump the starter....even for a split second.
Like always , I did not make myself clear. I have two separate requirements. First was a toggle switch to which Walt's model will suit me fine. And another switch for another project that requires a key so it can be removed for security. I purchased the perfect key switch from Digikey , but it has no detent. You can almost blow on the key when installed and rotate it (turning it on or off), not suitable .
Thanks Ron
Thanks Ron
rv7charlie
Well Known Member
Ron, if you haven't had any luck, try this site for a key switch.
http://gardentractorpullingtips.com/electric.htm
No personal experience with them, but you never know where useful options will be found.
http://gardentractorpullingtips.com/electric.htm
No personal experience with them, but you never know where useful options will be found.
Carl Froehlich
Well Known Member
I suggest looking at a ?start permissive? key switch. This can be either a keyed switch or a simple hidden toggle switch. If you use a keyed switch look for a 10 amp contact switch, like this: https://www.alliedelec.com/product/honeywell/84828-07/70111552/
Option for a smaller footprint would be one many 1 amp or so key switch that would operate a start permissive relay, the relay then provides the power to the starter solenoid.
Carl
