Hey guys,
Here an update on on how the transformer I have is dealing with various loads.
I bought some light bubs (actually, they are halogen lamps fitted in a light bulb, rated for 30W, 46W and 57W), and a simple Eco lamp (fluo type, 5W).
I used them either alone, or in series to create various loads for the secondary of the transformer. This is what I measured :
Lamp(s) | Output Voltage Vo (V) | Io Output current (A) | Power (W) | Requivalent (Ohms) |
No Load | 270.1 | 0.000 | 0.0 | -- |
5W | 266.3 | 0.048 | 12.8 | 5548 |
30W -- 30W | 256.7 | 0.100 | 25.7 | 2567 |
30W -- 46W -- 57W | 254.6 | 0.108 | 27.5 | 2357 |
30W -- 46W | 254.2 | 0.118 | 30.0 | 2154 |
30W -- 57W | 253.3 | 0.126 | 31.9 | 2010 |
30W | 250.3 | 0.144 | 36.0 | 1738 |
46W -- 57W | 247.8 | 0.164 | 40.6 | 1511 |
46W | 240.3 | 0.211 | 50.7 | 1139 |
57W | 232.3 | 0.262 | 60.9 | 887 |
I have added in attachment the graph plotted out of these data, for those of you interested. It appears pretty linear
.
Turns out I can compute (approximately) the expected output voltage for a given load current simply using V
o = (1000*(1.83-I
o))/6.72
Just to remind quickly the conditions:
- Transformer: Noratel AA53129 50VA, Prim: 230VAC, Sec: 2x115VAC, 133.1VAC on each windings with no load (from datasheet)
- Both secondary windings are connected in series
- and the measure voltage at the input (mains) is 234VAC@50Hz
Quite frankly, I still find this thing weird. I was somehow expecting to have something that would provide 230VAC over a given range of output currents.
I guess you need some output circuitry for this... Well I guess this will keep me busy for the next evenings