Old Hammond Transformer Ratings

Thread Starter

blah2222

Joined May 3, 2010
582
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
 

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MrChips

Joined Oct 2, 2009
21,620
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.
 

Thread Starter

blah2222

Joined May 3, 2010
582
I believe Hammond 167N60 is 60V C.T. 4A.

I have some old listings at work and will have a look some other day.
[/URL] useful.
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.
 

k7elp60

Joined Nov 4, 2008
562
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.
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:

Thread Starter

blah2222

Joined May 3, 2010
582
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.
 
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