Measuring interwinding capacitance

[cupoftea]

Hi,
This video says to short pri and sec coild then measure leakage inductance

 

[KlausST]

Hi,

what´s your question?

Klaus

 

[D.A.(Tony)Stewart]

that is correct for C
to shunt Lp, Ls

 

[cupoftea]

Hi, Sorry i was trying to redo it, but was too late...please find it here......not had enough coffee's yet i think in my case...
This video says to short pri and sec coils then measure their interwinding capacitance

However, this video says to just leave pri and sec open, and connect to them (ie not short the coils)

..which way would you say is optimal?

We will be using an LCR meter at 100kHz with Cs-D setting, 1V Test Level.

 

[D.A.(Tony)Stewart]

that is correct for C to shunt Lp, Ls
But just short Ls to measure leakage L on primary.

Mr. Product Mgr for R&S doesn't know how it works or your review was incorrect

 

[KlausST]

Hi,

I´d surely short them .. to get worst case capacitance.

Klaus

 

[D.A.(Tony)Stewart]

You've already made one error on SOA, I hope this is not the case of you missed a jumper

 

[KlausST]

added:
leaving the windings OPEN .. I would not be surprised to get different values when connecting the measurement device to the other winding terminal(s).

A transformer consists of windings, some are closer to the core (connected to one leg), some are more far away (connected to the other leg). Those far away will additionally see some of the primary inductance (not leakage inductance) of the winding.

I´m not sure how big the difference may be.

Klaus

 

[FvM]

Capacitances are regularly measured at 1 kHz.

 

[cupoftea]

Capacitances are regularly measured at 1 kHz.

OK thanks, i measured at 100kHz because that is the switching frequency. (well, switching frequency is 150kHz but 100Khz is generally "near" the various switching frequencies that get used, and its nice to keep it the same each time)

 

[KlausST]

Hi,

OK thanks, i measured at 100kHz because that is the switching frequency. (well, switching frequency is 150kHz

you know that
* measurement signal is pure sine
* while switching waveform rather is square wave

So any other waveform than sine has overtones .. multiples of the fundamental frequency.

Klaus

 

[cupoftea]

Thanks, i guess i should have pressed the "Z, theta" button on the LCR.?...and if the angle read -90degs or near that, then whatever frequency i was at was OK......since it must have been a reading dominated by capacitance if theta was right near -90degs.

 

[Easy peasy]

Interwinding is defined as between 2 wdgs, this is easy, intrawinding is the self cap, also easy, from the SRF.

 

[D.A.(Tony)Stewart]

Capacitances are regularly measured at 1 kHz.

At one time it was just dissipation factor at 120 Hz and low f C, now mfg's rate the ripple current at low and high f and commercial Philips LCR meters I used 25 yrs ago also had options up to 1 MHz
it gets nonlinear since there is a double layer effect in all caps (memory effect) except film and NPO ceramic. Although caps by this name are just obvious by their massive size in xx Farads, but it exists in all smaller caps too. this is also why one never uses X7R caps for a S/H cap.