Obviously, the problem comes from the fact "ungapped" which physically speaking is untrue...a little grease from the hand produces a (varying) gap. Always use a gap. If you cannot afford to have them gapped,use a piece of paper, about 3 mils thick.
core and momentarily magnetise it - hence the click. The more perfect the mating of the opposing faces the worse this will be.
nt where it can't get any more magnetised.
It's a pity you can't understand it.
It's still wrong and misleading.
earing the inrush surge as a bonk or thud.
You may think so, by my theory is that you are suffering from pedant-envy.
It's wrong vis-a-vis the phase of the mains when power is turned back on ag ain, which is - of course - random.
A fuse may blow because the core of the transformer has saturated and the c urrent through it's winding can get higher than intended, but it's the magn etic field going up from at an inconvenient starting value that creates the problem
e core > even if it wouldn't have saturated if soft-started
So you hadn't heard what caused the problem - just had to soothe irritated customers after it had happened.
I don't share your reading habits.
the noise.
Apart for the fact that you think the click comes from the core, and I susp ect the hand-wound coil.
Very kind of you to grant me that liberty. Since my current life expectancy is another 11.72 years, it's unlikely to happen any time all that soon, bu t your kind permission does allow me to drop dead any time my aging body fe els like it. It would do it even without your permission, but I suppose you could try to sue my estate if I did drop dead without your okay. It probab ly wouldn't be a profitable exercise, but you do waste a lot of time on unp rofitable activities.
-- Bill Sloman, Sydney
Bad advice.
-- Bill Sloman, Sydney
Please explain..
Pulse transformers are strictly worse with gap. The increased magnetizing current only burdens the circuit.
Likewise for current compensated (common mode) chokes, where the DC bias current is small, and the magnetization current must intentionally be very small (common mode impedance must be very high).
The main difference between pulse transformers and CMCs is, the former needs wide bandwidth (generally speaking, low LL and Cp), while the latter does not (can tolerate high LL).[1]
Real power transformers are usually better with a small gap, because the increased magnetization current either hastens the return to steady state conditions (the cause usually being transient startup conditions, like a full-width initial pulse instead of soft start), or allows control/protection circuitry to do its job (a peak current mode controller like UCC3808 will balance pulse widths very effectively, when magnetization current is a perceptible fraction of load current, more than a few percent let's say).
Such a transformer is strictly worse as a transformer, but the point is, practical considerations may dictate a small departure from the ideal.
Of course, _inductors_ store energy, and must be gapped. (Note that a flyback transformer is more descriptively called a multi-winding inductor.)
[1] Well, power line CMCs -- data line CMCs need low LL, and may even need controlled Cp, which is to say, a controlled characteristic impedance, as a proper TLT. This is visible in the diff mode impedance plots, when there are several peaks and valleys, corresponding to transmission line standing waves. This is proof that your data can have good signal quality, over bandwidths beyond the LF equivalent cutoff frequency, using such parts.Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
So you ramp up the duty cycle?
How does that reduce the stress, is it because you are worried about remanence field from the last time you exercised the transformer?
Cheers
Klaus
I'd suspect a circuit problem, not a transformer problem.
A small change in a transformer shouldn't affect a system.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
In a low-cost printed pulse xMHz transformer, used to pump a rectified load at a lower frequency rep rate, uncorrelated gating of the HF carrier could damage the driver if it saturated the transformer on the first pulse application.
Normal flux swing in the part was high, from -1/2Bsat to +1/2Bsat then back again. A mistimed first pulse could drive the core into 1.5xBsat. Ugly, damaging and slow to recover within the required lower frequency profile.
RL
On a sunny day (Thu, 09 Nov 2017 08:17:29 -0800) it happened John Larkin wrote in :
If there is the slightest DC component and no airgap, then any pressure on the 2 halves can change the thing from [partly] saturating to not-saturating.
That's one example of a circuit problem. The occasional clicking suggests either DC, or random remnant magnetization that causes saturation at the next startup.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
I did that once.
It was an ISDN transformer that we wanted to use as a pulse transformer, just at the edge of its volt-second range.
Those little 1:1:2:2 ISDN transformers are great.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
When you're operating near the edge, small changes matter. In this case, signal quality affects bit rate.
Cheers
-- Clive
Then don't operate near the edge. You may have a circuit or protocol problem, not a transformer problem.
What is your bit rate? How is the data encoded?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
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