[Amps] Need help understanding an old Transformer

[W5CUL]

Hi All, 

 

I need some help in determining the capability of an old transformer that I
ran across.  It is an old Thordarson CHT Series built some time in the late
30's early 40's.  The model number is T-15P21 and it weighs about 129lbs,
and was designed for continuous commercial service (CCS) at its rated
output.  What has me confused is how to determine its overall rated
capability.  It is an old style with a Center Tap on the secondary's, and
plenty of Sec taps for various voltages.  I actually found an old Thordarson
catalog which gives somewhat of a clue, but I suspect that I may not be
reading it right.  Here is what it says in the catalog for the T-15P21:

 

Sec A.C                        D.C                      D.C
Pri.              Pri.

Load Volts                    Volts                    M.A.
Volts           Watts

 

3440/3440                    3000                     500
115-230         1690

2980/2980                    2500

2340/2340                    2000

1815/1815                    1500

 

So what I am thinking, and please correct me if I am wrong, I would see 3440
Vac between either secondary leg and CT, or if across both 3440 secondary
legs, I would see 6880Vac.  The "3000" D.C Volts shown in the catalog is
only for one leg to CT and is rated low due to an older method of
rectifying; basically using a smoothing choke with one or two diodes.  The
.5mA at 3000Vdc rating is across only one of the 3440 secondary legs to CT,
with the other 3440 secondary leg to CT capable of the same amperage
simultaneously. Or, if across both 3440 secondary legs with no center tap,
the transformer could supply .5mA CCS at 6000Vdc, given a smoothing choke.
I also suspect that the 1690 Watts primary is in keeping with the one 3440
secondary leg to CT, even though it is under the Primary column, thus giving
a full rating across the primaries if both 3440 secondary legs were to be
utilized simultaneously to that of 3380 Watts. 

 

Let me know if I am on the right track or if I am missing something here. 

 

Thank you for the help!!

 

73,

 

Mike 

W5CUL