Old Hammond Transformer Ratings

Discussion in 'General Electronics Chat' started by blah2222, Aug 15, 2014.

  1. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
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    Hello,

    I found an old Hammond (Type 167 N 60) transformer in my parts bin and have a couple questions regarding their secondary ratings. I cannot find any information about this product as the ID is not listed on their website or anywhere for that matter.

    Primary:
    115 V. 60 CY.

    Secondary:
    25 VOLTS C.T. 0.5 AMPS

    Questions:

    1) Does 25V centre-tapped mean +/- 25V or +/- 12.5V?

    2) Are the secondary voltage and current ratings both RMS?

    3) What is a good rule of thumb for rating of a primary-side fuse given load/transformer ratings?

    Thank you
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    I believe Hammond 167N60 is 60V C.T. 4A.

    I have some old listings at work and will have a look some other day.

    60VAC C.T. means +/- 30VAC

    Voltage and currents are always R.M.S.

    60V x 4 A = 240VA

    Hence the primary requirements would be 120V x 2A

    A 2A fuse would work if your load takes less than 200W otherwise you can go for a 3A or 4A fuse.

    You may find this Design Guide useful.

    Edit: Sorry, I just saw the printing on your transformer.
    Go by what is written there: 25V C.T. 0.5A = 12.5VA

    A 500mA fuse is good enough.
     
  3. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
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    Thank you for the response.

    With regard the markings on the transformer though, wouldn't that mean it is 25V @ 0.5A and not 60V @ 4A?

    I'm going to test this with low-voltage AC and see what kind of shape it's in.
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,981
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    Note that the rectified DC output rating is significantly less than the AC RMS current rating.
     
  5. k7elp60

    Senior Member

    Nov 4, 2008
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    MR Chips is correct about the 116N60 transformer. I have an older Hammond catalogue and the charastics are listed.
    I think there is some missmarkings on the transformer pictured as the one the the cataloge is fully encased and seems quite a bit bigger than the one pictured.
     
    Last edited: Aug 16, 2014
  6. MrChips

    Moderator

    Oct 2, 2009
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    The transformer shown in the photograph is certainly not 240VA.

    It is a 166G25.

    No-load output is 28VAC.
     
  7. bertus

    Administrator

    Apr 5, 2008
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  8. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
    554
    33
    EDIT: see below.
     
    Last edited: Aug 19, 2014
  9. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
    554
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    On the scope I am seeing 80Vpp (28 Vrms) unloaded.

    I spoke with someone from Hammond and they said it is possibly a mislabelling, which would make sense because I can't find any reference to a 167N60 part being made.

    Looking into it further I found two Hammond catalogues which show a distinct change in product ID convention:

    Catalog 65 (1950's)
    Checking page 16 of this document for the 167 series, they use the '60' to denote cycles not secondary voltage and the letter seems to be arbitrarily chosen.

    Catalog 84R
    Checking pages 19/20 of this document for the 167 series, they use the letter to denote current rating and the digits proceeding to denote secondary voltage.

    This transformer is pretty old so I'm assuming it falls under the earlier convention, but I still can't seem to find that ID anywhere. There must be a catalog floating around somewhere that has it...

    Wondering if there is a reliable way to figure out the current rating for this device. It says 0.5A but I wouldn't mind confirming, because a higher rating would be nice.
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    I think I already told you.
    It is a Hammond 166G25.
     
    blah2222 likes this.
  11. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
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    Ah, yes looking at that part on Digikey it does seem to be it!

    Thank you
     
  12. alfacliff

    Well-Known Member

    Dec 13, 2013
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