[CR de Pro]Essai des fusibles isoclean

[FRANCKC]

Le post est réouvert, les derniers passages et interventions pouvant soulever une polémique inapropriée ayant été enlevés.
Je souhaite que la discussion soit à nouveau centrée sur le thème abordé ici.

Merci pour votre compréhension.

FRANCKC
Administrateur site

[Euterpe]

Un de mes collègues Canadien a effectué quelques mesures voici ses conclusions :

On fuses and directionality: having some spare moments and an abundance of curiosity, I spent some time looking at what you would get through a directional fuse in an AC line, after rectification and before filtering.

1. I started with a pure sinusoid at 60Hz, rectified it, and looked at the power spectrum. There is, of course, a DC term (0dB), then there are even harmonics at increasingly diminishing amplitudes: 120Hz at -5dB, 240Hz at -12dB, etc. These have to be filtered out to get DC.

2. I took a pure sinusoid at 60Hz, attenuated the negative-going portion by 10% (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms are there, but there is also a fundamental: 60Hz at -14dB. This makes the filtering harder.

3. I took a pure sinusoid at 60Hz, added an 10 degree phase shift to the negative-going portion (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms are there again, but there are also a fundamental and odd harmonics: 60Hz at -12dB, 180Hz at -22dB, (the rest are all around -22dB) . This makes the filtering even harder!

4. I took a pure sinusoid at 60Hz, added 10% 2nd harmonic distortion only to the negative-going portion (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms as the pure case are there, but there are also the fundamental and odd harmonics at diminshing amplitudes: 60Hz at -15dB, 180Hz at -17dB, etc. A little better than case 3, but still far worse than case 1.

5. I took a pure sinusoid at 60Hz, added 10% 3rd harmonic distortion only to the negative-going portion (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms as the pure case are still there, but there is also one odd harmonic: 180Hz at -14dB. This is better than the last three cases, but is still more stuff to filter than the pure sinusoid case.

The bottom line is that there is not much you can do to an AC signal that is going to be rectified that will not introduce additional harmonics that that you then have to filter out to get DC.

And what may those of us who may be terminologically challenged conclude from this?

A directional device that alters the amplitude, phase, or harmonic content of one half of an AC waveform that will be rectified and filtered to obtain DC only degrades the waveform compared to a non-directional device.
In fact, the direction of the device does not matter, because the current will flow through it the "wrong way" half the time either way.

[[Tonio]]

A directional device that alters the amplitude, phase, or harmonic content of one half of an AC waveform that will be rectified and filtered to obtain DC only degrades the waveform compared to a non-directional device.
In fact, the direction of the device does not matter, because the current will flow through it the "wrong way" half the time either way.

C'est marrant qd meme, ça fait 30 pages qu'on le dit...

[haskil]

Nous sommes sur un forum francophone et il n'est pas autorisé de publier de telles tartines non traduites.


Alain

[eboissier]

[expertdoc]

C'est marrant qd meme, ça fait 30 pages qu'on le dit...

Et en français en plus

[blounote]

- 山田さんは何を食べたいですか。

- 今晩は肉を食べたいです。

- 牛肉が好きですか。

- はい、大好きです。

- 牛肉とじゃが芋が好きですか。

- いいえ、じゃが芋が嫌いです。

[haskil]

Blounotte ! Soigne un peu mieux ton style et ton orthographe


Si tu veux que bientôt tes avis soient entendus quand bien même ils ne sont, à tout prendre, qu'écrits


Alain

[xere]

- 山田さんは何を食べたいですか。

- 今晩は肉を食べたいです。

- 牛肉が好きですか。

- はい、大好きです。

- 牛肉とじゃが芋が好きですか。

- いいえ、じゃが芋が嫌いです。

ا من رواد الموقع إلى جانب الموضوعات التى ليس لها أبواب فى الموقع توضع هنا

للوصول الى هذه المتفرقات

[Euterpe]

Nous sommes sur un forum francophone et il n'est pas autorisé de publier de telles tartines non traduites.


Alain

J'ai déjà posté plusieurs textes en Anglais et personne n'a rien dit, certains ont même traduits et commentés certains passages , et subitement ce n'est plus autorisé?

Sachant que ce n'était pas autorisé, je me serais abstenu, merci haskil, je m'en souviendrais.

Mais vous avez raison, le forum est francophone, je vais traduire le texte (la tartine) dés que je peux.
Désolé pour le dérangement...

[angus2]

Sachant que ce n'était pas autorisé, je me serais abstenu, merci haskil, je m'en souviendrais.

Mais vous avez raison, le forum est francophone, je vais traduire le texte (la tartine) dés que je peux.
Désolé pour le dérangement...

Il ne faut pas prendre la mouche, Alain plaisantait pour l'interdiction.

Ceci dit c'est vrai que sur le forum l'angais n'est pas une évidence pour tout le monde et il est plus convivial de donner un texte traduit ou alors d'en extraire l'essentiel pour faciliter la lecture de tous.

[blounote]

- 山田さんは何を食べたいですか。

- 今晩は肉を食べたいです。

- 牛肉が好きですか。

- はい、大好きです。

- 牛肉とじゃが芋が好きですか。

- いいえ、じゃが芋が嫌いです。

Juste pour le fun, la traduction de mon texte hautement philosophique qui constitue la leçon n° 12 d'un cours de japonais trouvé sur internet...quelque rudiments indispensables pour qui envisage un voyage au pays du soleil levant

- Que voulez-vous manger monsieur Yamada?

- Ce soir, je veux manger de la viande.

- Aimez-vous le boeuf?

- Oui, j'adore.

- Aimez-vous le boeuf avec des pommes de terre?

- Non, je déteste les pommes de terre.

[eboissier]

Maintenant, j'apprends le Japonais !!
Merci qui ? Merci HCFR !!

[zabc51]

Un de mes collègues Canadien a effectué quelques mesures voici ses conclusions :

On fuses and directionality: having some spare moments and an abundance of curiosity, I spent some time looking at what you would get through a directional fuse in an AC line, after rectification and before filtering.

1. I started with a pure sinusoid at 60Hz, rectified it, and looked at the power spectrum. There is, of course, a DC term (0dB), then there are even harmonics at increasingly diminishing amplitudes: 120Hz at -5dB, 240Hz at -12dB, etc. These have to be filtered out to get DC.

2. I took a pure sinusoid at 60Hz, attenuated the negative-going portion by 10% (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms are there, but there is also a fundamental: 60Hz at -14dB. This makes the filtering harder.

3. I took a pure sinusoid at 60Hz, added an 10 degree phase shift to the negative-going portion (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms are there again, but there are also a fundamental and odd harmonics: 60Hz at -12dB, 180Hz at -22dB, (the rest are all around -22dB) . This makes the filtering even harder!

4. I took a pure sinusoid at 60Hz, added 10% 2nd harmonic distortion only to the negative-going portion (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms as the pure case are there, but there are also the fundamental and odd harmonics at diminshing amplitudes: 60Hz at -15dB, 180Hz at -17dB, etc. A little better than case 3, but still far worse than case 1.

5. I took a pure sinusoid at 60Hz, added 10% 3rd harmonic distortion only to the negative-going portion (to mimic a directional effect), then rectified it and looked at the power spectrum. Essentially the same DC and even harmonic terms as the pure case are still there, but there is also one odd harmonic: 180Hz at -14dB. This is better than the last three cases, but is still more stuff to filter than the pure sinusoid case.

The bottom line is that there is not much you can do to an AC signal that is going to be rectified that will not introduce additional harmonics that that you then have to filter out to get DC.

And what may those of us who may be terminologically challenged conclude from this?

A directional device that alters the amplitude, phase, or harmonic content of one half of an AC waveform that will be rectified and filtered to obtain DC only degrades the waveform compared to a non-directional device.
In fact, the direction of the device does not matter, because the current will flow through it the "wrong way" half the time either way.

Je ne comprends pas trop l'anglais, mais j'ai l'impression de comprendre que ce monsieur fait un redressement double alternance et retrouve du donc une composante à 120Hz (rang 2) sur son DC.
J'ai quand même vaguement l'impression qu'il y a au moins un siécle que tous les electronicien sont au courant que dans du 50 Hz, 25 Hz avant passage généralisé au 50 hz en Europe, et redressement double alternance on retrouve le double de la fréquence d'origine et ses harmoniques supérieures. D'où l'intérét d'un bon filtrage en pi

[Euterpe]

Disons qu'en substance il dit :

C'est que, en passant par un élément à effet d'orientation ( « directionnel » ) (ici simulé par une diminution du voltage à la partie négative de l'onde), que l'onde alternative, un fois redressée, comporte des harmoniques additionelles.

Ces harmoniques compliquent la tâche du redresseur et du filtre ; le courant direct qui en sort est contaminé.