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Class B Viking B-2 Transformer Schematic

kellys_eye

Jun 25, 2010
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I think the 'Y (why) don't use BR-R for step up voltage' was the question........

There's no reason why you can't use BR-R to step up the voltage. Transformers are 'bi-directional' but you MUST be cautious of the absolute ratings to prevent overloading.
 

S.A.Haleem

Mar 6, 2018
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I think the 'Y (why) don't use BR-R for step up voltage' was the question........

There's no reason why you can't use BR-R to step up the voltage. Transformers are 'bi-directional' but you MUST be cautious of the absolute ratings to prevent overloading.

Hi Kellys
Thanks for the question
Y- means yellow (Thought this wire cannot be used, I guess this will be another primary combined with black)
Using BR-R could be tricky and dangerous, because I guess this is the step up output, to get them to output 230VAC you will need to input the secondary with the correct AC (low) voltage.
 

S.A.Haleem

Mar 6, 2018
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Class B Viking Transformer Schematic.jpg

hi,
I have updated the schematic !
 
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Kabelsalat

Jul 5, 2011
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You miss voltage reading for BRN-BLU, can't know the wiring without that.

Also the drawing have two terminals both labeled "BLU", both at primary and secondary side, which make little sense for me. Are those connected?

What have the transformer being used for in the past? Dor bell?
 

kellys_eye

Jun 25, 2010
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The transformer is a 'typical' example of primary over-winding.

Given the wide range of global AC mains standards - anywhere from 110V to 250V (possibly wider) - the manufacturers have additional taps added to the main winding which allows the user to select the correct (or nearest possible) primary input voltage.

You have a FIXED primary mains supply (quoted as 230VAC) therefore if you use a different primary voltage tap you get the equivalent increase or decrease in output voltages.

With 230V applied you show that you get 15VAC out.

Your diagram states 12V and 18V for the other inputs and these represent a 20% variation lower/higher which, when applied to the primary, mean the other taps are meant for 190V and 275V inputs respectively.

The BRN and R taps will be 'in between' taps and only have a nominal difference of 20V between them so CANNOT BE USED together to apply the mains input.

I suggest your transformer has a primary something like:

BLK -0V (neutral)
R - 210V
BN - 220V
GN - 230V
BU - 240V
Y - 250V
 
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S.A.Haleem

Mar 6, 2018
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You miss voltage reading for BRN-BLU, can't know the wiring without that.

Also the drawing have two terminals both labeled "BLU", both at primary and secondary side, which make little sense for me. Are those connected?

What have the transformer being used for in the past? Dor bell?
hi Kabelsalat
One Blue Wire is on the Primary Side another on the Secondary side, This transformer is salvaged from an old UPS and I had searched the net for schematics and I couldn't see anything, that's why had to find out myself and the same is uploaded for people searching for information. The voltage across BRN-BLU seemed to fluctuate between 20- 25VAC, anyways when you have 6,7.5,9,12,15,18 Volts as output why do you need to use BRN-BLU, so I decided to ignore the same. The Transformer may have a rating of 5-7Amp and certainly not used for a door bell !
 

kellys_eye

Jun 25, 2010
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If the transformer is from an old UPS then the extra windings are commonly used to create a 'variac-type' adjustment that enables the transformer to maintain a reasonably level UPS output voltage (mains) despite a wider swing in input supply. This is referred to as on-line switching where the incoming supply is regulated to the best possible extent before the UPS decides that it can't cope and then switches to its internal battery supply.

Relays will be controlled by voltage monitoring circuitry to switch the over-windings in or out of circuit as the mains supply varies. If you have the whole UPS and it's still working you can prove this by applying a variable AC source to the mains input and, as the supply changes, you can hear the relays clicking in and out in an attempt to maintain the output (non-UPS driven) at a reasonably level setting. Either side of 'reasonable' and the UPS will change to its internal inverter circuitry.
 

S.A.Haleem

Mar 6, 2018
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The transformer is a 'typical' example of primary over-winding.

Given the wide range of global AC mains standards - anywhere from 110V to 250V (possibly wider) - the manufacturers have additional taps added to the main winding which allows the user to select the correct (or nearest possible) primary input voltage.

You have a FIXED primary mains supply (quoted as 230VAC) therefore if you use a different primary voltage tap you get the equivalent increase or decrease in output voltages.

With 230V applied you show that you get 15VAC out.

Your diagram states 12V and 18V for the other inputs and these represent a 20% variation lower/higher which, when applied to the primary, mean the other taps are meant for 190V and 275V inputs respectively.

The BRN and R taps will be 'in between' taps and only have a nominal difference of 20V between them so CANNOT BE USED together to apply the mains input.

I suggest your transformer has a primary something like:

BLK -0V (neutral)
R - 210V
BN - 220V
GN - 230V
BU - 240V
Y - 250V

hi Kelly's eye
Your observation may be correct, regarding BLK to Y, it could be tapping for varied AC inputs, but BRN & R on the primary side are actually secondary ones. My measurements of resistance as below:-
1.(primary side) BRN-R - 1.2 ohms (it cannot be a primary)
2. (primary side) BLK-G - 8 ohms
3. (primary side) BLK-Y - 7.3 ohms
4. (primary side) BLK-BLU - 6.8 ohms
5. (secondary side) BRN-BLU - 0.8 ohms
6. (secondary side) BRN-RED - 0.8 ohms
I hope this will clear you doubts...
 

S.A.Haleem

Mar 6, 2018
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Anyone please tell me what will happen when I switch primary taps to get different voltages at the secondary. All with the same 230VAC, ie Black-Green to get 6VAC & 12VAC on the secondary, Black-Yellow to get 7.5VAC & 15VAC on the secondary an so on. Can I use the transformer continuously this way?
 

kellys_eye

Jun 25, 2010
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Do the BRN and R terminals show continuity to any other terminals?

Without getting the specifications from the manufacturer all you can do is power the device up and load the output to the rated level and measure the transformer temperature rise.

Transformers from UPS devices aren't usually built for continuous operation.
 

xP01S0Nx

Nov 15, 2022
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hi Kelly's eye
Your observation may be correct, regarding BLK to Y, it could be tapping for varied AC inputs, but BRN & R on the primary side are actually secondary ones. My measurements of resistance as below:-
1.(primary side) BRN-R - 1.2 ohms (it cannot be a primary)
2. (primary side) BLK-G - 8 ohms
3. (primary side) BLK-Y - 7.3 ohms
4. (primary side) BLK-BLU - 6.8 ohms
5. (secondary side) BRN-BLU - 0.8 ohms
6. (secondary side) BRN-RED - 0.8 ohms
I hope this will clear you doubts...
Excuse me, I'm new to this world also I'm not a native speaker so my English isn't the best, I was wondering if you can tell/ teach me how can I use this Transformer. I need it for a 28 VDC application with a LM317T for a Variable supply voltage source, but i don't even know how the transformer works which winding is the ono that should be connected to the network, is it the secondary or the primary? My transformer is a "080-48126-00 0651 Class B Viking B-2 E210832". thank you
 

kellys_eye

Jun 25, 2010
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Please don't hijack old threads - a new thread would be just as applicable.

Post a picture of your transformer. If you have a test meter you can often measure the primary and secondary resistance - the primary being higher (assuming it's a low voltage secondary transformer that you have).
 

xP01S0Nx

Nov 15, 2022
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Please don't hijack old threads - a new thread would be just as applicable.

Post a picture of your transformer. If you have a test meter you can often measure the primary and secondary resistance - the primary being higher (assuming it's a low voltage secondary transformer that you have).
Ok, first at all thanks for answering my doubt.Then here is the photo of the transformer and some measurements that i take of the transformer, this are the measures:


for what looks like the primary (the thicker wires)

Imagen de WhatsApp 2022-11-15 a las 19.18.34.jpg
BLUE-RED: 0 Ω
RED-BROWN: 0 Ω
BROWN-BLUE: 0 Ω
and the thinner wires
BLUE-BLACK: 3.4 Ω
Y-BLACK: 3.6 Ω
Y-BLUE:0.3 Ω
BROWN-RED: 0.8 Ω
 

kellys_eye

Jun 25, 2010
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The blue-red-brown wires are likely the secondary and look to be a low voltage x-0-x output (i.e. centre-tapped AC secondary).

The primary is (guessing) wired for 220 or 240V (black-blue or black-yellow respectively) with the other two potentially being taps at lower voltages (perhaps 210/200???) either way USE A FUSE in the mains line (500mA) before connecting - keep your hands well clear and then measure the output AC volts (blue/red/brown). If you get the expected LOW AC volts and nothing untoward happens then carry on from there.
 
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