How to wire a toroidal transformer..need advice

[bgolash]

Hi Group
I intend to use this for two of my steppers. I already have one power
supply in place. The two motors are 5 amps each with voltage rating
of 3.1. Could someone help with the transformer wiring. I`m not
certain how to configure the wires.

0V........ 115v.........230v
BLK RED YEL
O/P:0V... 35v 0v....35v
BLK BLU GRN GRN

From a ebay auction:
You are bidding on a new 600VA toroidal transformer. It is precisely
made for high-end power amp or equipment. It has very low power loss
and magnetic leak. Labeled input 115 / 230 VAC 50/60 Hz (single coil
with center tap) and outputs 35VAC x 2 (dual coils). Mounting
hardware is included. The test results are excellent.
Voltage Test Result:
TEST CONDITION: Apply variable voltage to primary coil (115V
terminals) from 100-180VAC. No load on secondary coils.
1. Primary V = 100VAC, Primary I = .03A
2. Primary V = 110VAC, Primary I = .03A
3. Primary V = 120VAC, Primary I = .04A
4. Primary V = 130VAC, Primary I = .05A
5. Primary V = 140VAC, Primary I = .11A
6. Primary V = 150VAC, Primary I = .15A
7. Primary V = 160VAC, Primary I = .63A
Load Test Result:
TEST CONDITION: Input 120VAC 60Hz to the primary coil; parallel 2
secondary coils, 10 ohm 250W resistors as dummy load and room
temperature at 25 degree C. Temperature rises 6 degree C after an
hour test at load #5.
1. Primary I = 0.03A, Secondary V = 40.5VAC at 0.0A
2. Primary I = 1.36A, Secondary V = 39.6VAC at 3.96A
3. Primary I = 2.66A, Secondary V = 38.6VAC at 7.72A
4. Primary I = 3.92A, Secondary V = 37.9VAC at 11.37A
5. Primary I = 5.10A, Secondary V = 37.1VAC at 14.85A
Dimension – 5.0" Diameter x 2.7" High

[vladdy]

Pretty straighforward..


0V........ 115v.........230v
BLK RED YEL
O/P:0V... 35v 0v....35v
BLK BLU GRN GRN

Neutral to BLK [white wire from wall / cord]
HOT [115v] to RED [black wire from wall /cord]

and probably a ground wire to some lug on the body
[green for wall / cord]

Output One 35v
BLK to Neg [-] on recifier
BLU to Pos [+] on rectifier

Output Two 35v
GRN ??
wait a minute, you sure that is the way they are labeled??

{PROBABLY} the two greens might be the NEG or grounds, perhaps even common
and the BLK and BLU are the positive outputs..

check the connector labels again...or is it GRN GRY??

[Al_The_Man]

The original post show two secondaries apparently connected in parallel, if so , the thing to watch is that the secondaries are phased correctly otherwise they will be in opposition. this can detected by a simple voltage test, with a ONE leg of each secondary connected together and the other two unconnected there should be zero voltage across the two open ends for them to be in phase.
If not swop one of the connected ends for its other leg.
Al

[BobLWeiss]

I bought this same transformer this week on ebay. Its better to hook them up in parallel so you get max amps out of it. Make sure you get a high amp rated rectifier and cap. These look like nice transformers and the money isn't bad either.. What size did you get? I got he 35v x 2 and 10v on the secondary. I can use the 10v rectified seperatly and come out with 12vdc and 5vdc for the logic and spindle motor. Where did you get your cap(s) from? What size did you get?

[ViperTX]

Okay, well if you look at the max. secondary current you need to look at large diode bridges (seems that 20 amps is more readily available then 50 amps, I got mine at http://www.mouser.com for about $5 each). I opted for 2 smaller bridges (20 amps), and 47,000 microfarad caps on each secondary.

[BobLWeiss]

Originally Posted by ViperTX and 47,000 microfarad caps on each secondary.

Where did you get a cap like that? Mouser? What voltage is it rated for?
How much?

[ViperTX]

Yes, they are Sprague units 47,000 microfarad at 70 VDC or was it 100....hmmmmm anyway about $32 each...which is about what the surplus units are going for and these are brand new.

[BobLWeiss]

Originally Posted by ViperTX Yes, they are Sprague units 47,000 microfarad at 70 VDC or was it 100....hmmmmm anyway about $32 each...which is about what the surplus units are going for and these are brand new.

Why did you use such a large valued cap? This is a linear powersupply so I would figure you could get away with 10,000 or a little less. Am I wrong?

[ViperTX]

When I designed the supply it was for 2.5 % ripple...which at the stated load of 30 amps resulted in a 250,000 microfarad cap....so, I adjusted the value and I should have about 5 % ripple on each output....I've separated the 2 secondaries and feed each secondary into it's own bridge and each output has a 47,000 microfarad capacitor....since I seriously doubt that I'll actually draw a full 15 amps from each output....I expect the ripple to be pretty low.

Actually switch mode type power supplies can use much smaller capacitors because the frequency they use to convert the DC back....I won't get into it.....anyway SMPS are different.

[BobLWeiss]

Originally Posted by ViperTX since I seriously doubt that I'll actually draw a full 15 amps from each output.

I thought the transformer was rated at 15amp in parallel mode using both output coils?

[Al_The_Man]

Unfortunately the post does not give the VA rating, but according to the test it look like it held up ok with 15 amps with the windings in parallel.
Al

[ViperTX]

Originally Posted by Al_The_Man Unfortunately the post does not give the VA rating, but according to the test it look like it held up ok with 15 amps with the windings in parallel. Al

Good catch...the one I have is a 27 volts at 30 amps.