Transformer wire color codes?

Question

I have a standard transformer with 7 wires:
2 black
2 red
2 yellow
1 red/yellow striped

What connections do these wires correspond to?
That is, which should connect internally to the primary coil, the secondary coil, and coil-taps (based on the number of wires, I assume that the secondary coil is tapped).

I must determine this in order to connect the wires (externally) appropriately.

Any help is greatly appreciated!

Answer 1

There is no standard color code for the wiring of a transformer. One way to tell what coils are what is to measure the number of windings on a digibridge/LCR meter. If this is a step-up transformer, the secondary will have the most windings, and if it is a step-down transformer the primary will have more windings. Do you know the know the manufacturer or model number of the transformer? Is there a label on it of some kind?

However, there IS a TYPICAL winding configuration based on the colors. This is not guaranteed. If you wish to go by this, please use caution.

Black - primary winding
Red - secondary winding
Yellow/Red - secondary tap
Yellow - low voltage secondary winding

Here's a few websites confirming my statement, but remember this is just TYPICAL, not definite for your transformer.
http://www.radioremembered.org/xfmr.htm
http://www.tpub.com/neets/book2/5i.htm

Once again, be careful!!!!

EDIT: Thanks Steve. You make good points as well. The wire for the higher voltage winding should be smaller diameter (unless this is a small transformer, in which case all wires might be of the same gauge). This is because more current is carried in the low voltage winding. And again, stay safe!

Answer 2

Transformer Wire Colors

Answer 3

Raptor gave good info.
I would add just a few points:
1. The high voltage winding usually has the smaller gauge wire.
2. The high voltage (primary) winding also usually has a higher DC resistance and fundamental frequency impedance than the secondary.
3. Be sure to scrape the insulation off the wires before checking the resistance. Many years ago, an idiot I was working with didn't recognize that the wires had enamel insulation on them, and connected the transformer backwards. It was a 480 V / 1 V (or so) instrument transformer. We lost a lot of good equipment and nearly lost people because of that screwup. The recorder saw 2 kV before it died.

Answer 4

The odds are fairly good that the black wires are primary, the red wires are one secondary, the yellow wires are another, and the striped wire is a center-tap on one of the secondaries. There is a standard ritual for identifying the characteristics of an unknown transformer: first, use an ohmmeter to identify which wires to a single winding, and which winding has the highest resistance. Next, apply power; the safest way is to use a 40-watt (or thereabouts) light bulb in series with a 120 volt source, and connect this to the highest-resistance winding. Now measure the voltages across each winding. That will give you the turns ratios, and you can get an indication from the physical size of the device as to how much power it can handle.

Answer 5

Pin Number Wire Color Function 1 Not Used Not Used 2 Black Ground 3 Grey Right Positive 4 Grey/Black Right Negative 5 Blue/White Amplifier Remote 6 Red 12 Volt Switched 7 Yellow 12 Volt Constant 8 White Left Positive 9 White/Black Left Negative

Answer 6

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What is the question? If you are asking what the codes are, there is no universal standard. What country, and what type of transformer?

Answer 7

Chances are the black leads are primary. An ohmmeter can tell you what is happening on the secondary. Try putting 24VAC on the black leads and see what voltages come out. My guess is you can calculate out the voltages using ratios.

Answer 8

Nameplate, have you ever work on anything Irv? You re living in a Dreamworld if you think everything has the proper labeling or any labeling for that matter!!!

Answer 9

UUUUUUh. Wouldn't the required nameplate have
a diagram with the windings/ connections indicated?
They usually do.