Welcome! Becoming a registered user of ShortWingPipers.Org is free and easy! Click the "Register" link found in the upper right hand corner of this screen. It's easy and you can then join the fun posting and learning about Short Wing Pipers!

Thanks Thanks:  0
Likes Likes:  0
Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 50

Thread: Alternator Field Switch

  1. #21

    Join Date
    Feb 2010
    Location
    Eufaula, OK
    Posts
    849
    Post Thanks / Like

    Default Re: Alternator Field Switch

    Quote Originally Posted by CTJER View Post
    In reply to SMO22; yes master is traditional under seat DPDT.

    Chris my understanding is that with the field off, the drag on the starter will be reduced during start....

    Jeff, what do you men by "generator switch" ? I don't see one in the Colt electrical schematic. Are you referring to the generator CB?

    Jerry
    The engine is actually running before an alternator starts producing power and creating a drag. If I recall correctly the rpm required is between 500 and 700. An alternator will fall offline if you can get the engine to idle slow enough.

    It had to have a generator switch if it was a conversion. Possibly in conjunction with the master switch. I have not worked or flown a Colt so I don’t know the original switch configuration but my Pacer had a 3 way toggle under the seat. I think up was battery and generator, center was off and down was battery only.

    Steve and I use the same switch.
    Last edited by Jeff J; 01-18-2019 at 11:58 AM.

  2. #22
    Gilbert Pierce's Avatar
    Join Date
    Nov 2007
    Location
    Germantown, Tennessee 01TN
    Posts
    4,427
    Post Thanks / Like

    Default Re: Alternator Field Switch

    At one point in my working life I had to develop processes to remanufacture alternators. The finished alternators were run a test bench. One of the checks was “turn on rpm”. They don’t turn on immediately but once on they will generate voltage at a lower rpm then the turn on rpm. Turn on rpm is higher than what the starter can turn the engine over.

    My 31 Ford pickup idles about 450 rpm. Once started I have to rev it once to turn my retro fitted Delco alternator. Once on it will usually keep producing power at idle.
    Last edited by Gilbert Pierce; 01-18-2019 at 04:29 PM.

  3. #23
    andya's Avatar
    Join Date
    Dec 2007
    Location
    UT47
    Posts
    1,995
    Post Thanks / Like

    Default Re: Alternator Field Switch

    the Jacobs on my 195 is similar, need to get it to 1000 rpm or a little over then it will stay
    on down to 650 to 700 during warm up. No I have an idea why. Thanks Gilbert
    "Progress is our most important problem"

  4. #24

    Join Date
    Dec 2015
    Posts
    546
    Post Thanks / Like

    Default Re: Alternator Field Switch

    Quote Originally Posted by CTJER View Post
    I have the InterAV alternator installed. No Field Switch that I can find. The Installation Instruction Schematic shows "original field switch". The AC electrical schematic shows nothing like this. Is such a switch required? If so can someone recommend a part number and wire size?

    Jerry
    Quote Originally Posted by CTJER View Post
    In reply to SMO22; yes master is traditional under seat DPDT.

    Jerry


    Original field switch, have you looked at it to see if the original generator field pole on your DPDT master is connected to your alternator field wire? If you have a DPDT master than that was how your generator was wired, one pole connected battery to buss, other pole closed the generator's own 12 volt field circuit to tell the generator to turn on. Does the alternator stay on when you turn the master switch off? If it turns off than you know the DPDT master is also your alternater field switch

    Quote Originally Posted by Jeff J View Post
    It had to have a generator switch if it was a conversion. Possibly in conjunction with the master switch. I have not worked or flown a Colt so I don’t know the original switch configuration but my Pacer had a 3 way toggle under the seat. I think up was battery and generator, center was off and down was battery only.
    I thought the DPDT masters were battery and generator both on in either ON selected position. Did Piper wire them with battery only in one ON position?

    I've seen alternators wired like that.

    If Jerry's alternator is using the original generator's field switch (DPDT master possibly?)
    If it is, I am curious which way they put 12 volts on the generator's old field pole of that DPDT master? Is this in the STC?
    Last edited by SMO22; 01-18-2019 at 07:17 PM.

  5. #25
    Administrator Steve Pierce's Avatar
    Join Date
    Nov 2007
    Location
    Graham, Texas, United States
    Posts
    15,454
    Post Thanks / Like
    Blog Entries
    1

    Default Re: Alternator Field Switch

    Quote Originally Posted by SMO22 View Post
    Original field switch, have you looked at it to see if the original generator field pole on your DPDT master is connected to your alternator field wire? If you have a DPDT master than that was how your generator was wired, one pole connected battery to buss, other pole closed the generator's own 12 volt field circuit to tell the generator to turn on. Does the alternator stay on when you turn the master switch off? If it turns off than you know the DPDT master is also your alternater field switch



    I thought the DPDT masters were battery and generator both on in either ON selected position. Did Piper wire them with battery only in one ON position?

    I've seen alternators wired like that.

    If Jerry's alternator is using the original generator's field switch (DPDT master possibly?)
    If it is, I am curious which way they put 12 volts on the generator's old field pole of that DPDT master? Is this in the STC?
    I installed a few alternators recently and removed the wire from the DPDT switch and installed it to the 5 amp CB switch. I guess you could use a CB and retain that switch and be a simple install.

  6. #26

    Join Date
    Dec 2015
    Posts
    546
    Post Thanks / Like

    Default Re: Alternator Field Switch

    Quote Originally Posted by Steve Pierce View Post
    I installed a few alternators recently and removed the wire from the DPDT switch and installed it to the 5 amp CB switch. I guess you could use a CB and retain that switch and be a simple install.
    That's exactly what I'm wondering, if they used a five amp circuit breaker from the bus and ran that to the old generator field pole on the master.
    Last edited by SMO22; 01-18-2019 at 07:35 PM.

  7. #27
    Administrator Steve Pierce's Avatar
    Join Date
    Nov 2007
    Location
    Graham, Texas, United States
    Posts
    15,454
    Post Thanks / Like
    Blog Entries
    1

    Default Re: Alternator Field Switch

    That is what Piper did.

  8. #28

    Join Date
    Feb 2010
    Location
    Eufaula, OK
    Posts
    849
    Post Thanks / Like

    Default Re: Alternator Field Switch

    Quote Originally Posted by SMO22 View Post
    I thought the DPDT masters were battery and generator both on in either ON selected position. Did Piper wire them with battery only in one ON position?
    I think you are correct for most installations. It's been nearly 20 years since I did the conversion so some of the details are lost to time but I think mine was wired more like the lined out diagram on drawing 12629 when I started the conversion.

  9. #29

    Join Date
    May 2009
    Location
    Navarre, FL.
    Posts
    441
    Post Thanks / Like

    Default Re: Alternator Field Switch

    If I recall correctly there is a circuit breaker, perhaps 5 amp called out for the field circuit.
    I used a 5 amp circuit breaker switch to be able to turn off the alternator.
    I believe there should be a placard that says:

    > This Aircraft is alternator equipped <
    Turn off field circuit switch(generator switch)
    before opening circuit breaker or turning off battery master switch.

    Do not run engine, operating alternator without battery connected in circuit.

    So yes Virginia, there is a Field Switch

  10. #30

    Join Date
    Sep 2015
    Posts
    18
    Post Thanks / Like

    Default Re: Alternator Field Switch

    When it is real cold, turn alternator field off to reduce drag on the start up. Increases chance of starting in marginal startup situations. Similar to switching to left mag only.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •