DP-241-5-24L

Support Q&A
1

------Question for DP-241-5-24L Please Put your question below------

I have several transformer part number above for a college lab. I connected the two white together and the two black together to a two-prong plug. When I plug that to the 120V wall outlet I see smoke and smell burning. What is going on? What is the problem here. Is there a fix? Or is the transformer broken? I have about a dozen of these. Kindly assist.

Leo

2

From what you’re describing it sounds like you wired up the dual primary in parallel which is correct.

image
image1152×648 40.9 KB

I guess the question is was your secondary wired up to anything or possibly had a wire inadvertently shorted? What is the current draw of what your secondary is wired to?

It does sound like your transformer isn’t operational at the present state.

3

Thanks, the wiring on the primary is good.

Nothing was wired to the secondary. I just connected to a Voltmeter and a scope. I haven’t measured the current. I turned it off out caution. So what is the resolution. I don’t want to connect test the other to make sure I don’t experience the same.

4

Before connecting to mains, testing a transformer you would test the primary for resistance and you should see low resistance but not a dead short. Similar resistance test for the secondary.

There’s a chance the transformer’s primary or secondary was physically compromised and shorted internally. Otherwise watch where the secondary wires are to make sure you don’t have shorted leads when wiring the transformer up.

Also check to make sure you do not have continuity between the primary and secondary.

After those have been checked you can wire up the mains and test the AC voltage on the output with a multimeter.

5

I will try those steps. I will let you know. Thanks

6

I just made the measurements you recommended. They seem to pass for both the defective transformer and the one I have not connected to the outlet.

So there appears to be no continuity between primary and secondary.

The primary resistance is 70 ohms. The secondary is 4.5 ohms for both transformers.

So what gives?

7

I tested the other transformer. I have not smelled nor seen smoke. I get a clean signal about 40 peak to peak and 14.5 RMS voltage.