Talk:Rectifier

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In an alternator with an eight-diode rectifying unit, what are the last two diodes for? I can't find any information on this.

Some alternators are four-phase rather than three-phase. In the schematics I'm familiar with, these are the units that require eight diodes. (two diodes for each phase) —Preceding unsigned comment added by 67.161.213.4 (talk) 01:29, 30 November 2007 (UTC)

Images are slightly too big. I increase the text font and that shoves the image to right.

a rectifier is a circuit which converts bidirectional current(ac) to unidirectional(dc). earlier rectifier was a single diodeconnected to the output of a transformer.but there was some ac still present in the output which is measured by a factor called ripple factor.therefore a low ripple is desired in output of rectifier the above arrangement is known as half wave rectifier, then to remove the ac a full wave rectifier was used this arrangement was of two diodes.

This page should discuss the older technologies that have been used for high-capacity DC power systems, such as motor-generator sets and mercury arc rectifiers. -- Anonymous, 05:25 June 11 (UTC)

Have been trying to find out what a half-wave rectifier is, and there's nothing on the page itself about this.

This page should also discuss controlled rectifiers

Contents

[edit] more stuff

whats the ripple frequency for a half wave rectifier plugged into a line voltage?

does the filte rcapacitor act as a low pass or high pass filter?

does the filter capacitor reduce ripple voltage or ripple frequency?

if a diode fails in a ful wave, what happens to ripple voltage and frequency?

IF THESE INCREASE THIS WILL MAKE RIPPLE VOLTAGE

resistance load current

if a filter capacitor opens, ripple voltage equals? what if it shorts?


just some interesting questions you may want to include in the article!

[edit] "Rectifier efficiency"

The eight / pi^2 figure does not refer to the ratio of output power to input power; it only refers to vdc^2/vac^2. The two are not at all the same. 19% of the input power is not dissipated by the rectifier under ideal conditions. That part needs to be rewritten.

Remember the rectifier effiency is the power of the output DC component over the AC input power. Not the total output power over total input power (which would be 100% for an ideal fullwave rectifier).
A quick google search for "rectifier efficiency" does not show this to be a common definition for those words. I can't imagine why it would be; why would that number (average Vout divided by peak Vin, all squared) ever be meaningful? I have therefore removed the definition, and the rest of the section was more or less completely incoherent, so I removed that as well.

I have no idea, either, where it came from. However, if you look at the math (integrate), the ratio of peak DC voltage to mean DC voltage (not RMS, but true mean) for a rectified wave, is VpeakDC/VmeanDC = pi/2. So your voltage when you filter it, will actually increase by that much. And power by the square of that. But these give "efficiencies" of greater than 1, basically because the smoothed DC output is at AC peak voltage, not AC (RMS). If the AC(peak) is AC(RMS)*SQRT2 and we forget diode drop and set AC(peak) = DC(peak), then the ratio of AC(RMS) to DC(mean) voltage is:

VAC(RMS)/VDC(mean) = [V(peakDC)/(SQRT2)]/V(meanDC) = pi/(2SQRT2) = 1.11

The inverse of this is about 90%.

So I don't know where this figure used comes from. The only thing that gives 4/pi^2 is the square of VDC(mean)/VDC(peak), or VDC(mean)/VAC(peak). But I can't see the physical meaning of either ratio. SBHarris 03:05, 20 August 2006 (UTC)

[edit] Music

I first encountered rectification when researching how to build myself a guitar effects pedal. The output frequency of a full rectifier is effectively double the input frequency, and is therefore convenient in producing an "octave" effect.

This is really about the extent of what I know about the topic, and if someone more knowledgeable could insert it into the article in a better articulated fashion, I think it would be a good addition. If you think I articulated the idea well enough, feel free to just cut and paste it into the article. Shaggorama 00:04, 6 March 2006 (UTC)

[edit] Change article title

I suggest a change of title. This article is called rectifier (after the device) then goes on to talk mostly about rectification (the process). I suggest that

  • This rectifer article be renamed to rectification.
  • rectifier be redirected to diode

John Dalton 21:10, 15 March 2006 (UTC)

I would go along with the rectification change, although when done you know somebody's just going to carp that the article goes on to talk about various kinds of rectifiers, and should be called THAT. You want verb or noun?

I object to the change to diode because many of the old high-power systems (before the fancy silicon high power diodes) like arc rectifiers and AC-powered DC-generators, were certainly not diodes in the sense that we know them. They need to be added into the article as has been noted, but nobody has gotten around to it yet. Eventually. SBHarris 09:07, 4 September 2006 (UTC)

[edit] Peak loss

Maybe it should be pointed out that the peak loss for full wave rectification is 2 times 0.7, as two diodes are involved? Done that - JJ

[edit] anyone fancy

drawing the input/output graphs for the 3 phase bridge? ;) Plugwash 22:32, 3 September 2006 (UTC)

Notice the diagram for the full rectification. Shouldn't there be a flat portion between each hump? Until each diodes passes its specified voltage (~.6-.7V for Si diodes) then there will be no current across the load?

Yes, real diodes will introduce a small flat portion, i wonder though if introducing this into the diagrams will confuse more than it will help though. Plugwash 18:02, 23 October 2006 (UTC)

[edit] Rectifier Relationships

I'm doing my lab report on rectifier circuits and I really need rectifier relationships both Vdc and Vrms values produced by all types of rectifiers. Well current might be added as well. I have some, might add them, when I finish, cause it is due soon. Can anyone please add them? —The preceding unsigned comment was added by Dmitrij.ledkov (talk • contribs) 21:51, 12 February 2007 (UTC).

The relatonships depend on the design of the rectifier, the properties of the components, and the load. We might be able to provide approximate relationships; how accurate do the relationships need to be? --Gerry Ashton 22:44, 12 February 2007 (UTC)

[edit] "Rectifier Diode" image

This is not a diode this is an SCR (notice the gate connection). —The preceding unsigned comment was added by 203.166.229.52 (talk) 14:36, 19 February 2007 (UTC).

[edit] 3-phase rectifier

Is there a significance in which order the 3 live wires are fed into it, or can the connection be arbitrary? --194.251.240.114 23:45, 27 March 2007 (UTC)

The answer to that question should be obvious from the schematic. Plugwash 20:53, 30 March 2007 (UTC)

[edit] What is "RMS"?

what is a "rms"?

RMS stands for root mean square. If you have alternating voltage applied to a resistor, and you would like to know how much DC voltage, applied to the same resistor, would produce the same power, you can take the voltage at each instant, square it, and then find the average squared voltage over a suitable period of time (one cycle of a sine wave, for example). Then take the square root of the mean squared voltage.
The same procedure works for current too. --Gerry Ashton 16:52, 27 July 2007 (UTC)

[edit] Other uses of rectifier

There are other definitions of the word Rectifier that have been ignored, such as:

rectifier - a person who corrects or sets right; "a rectifier of prejudices"

"rectifier." WordNet® 3.0. Princeton University. 05 Sep. 2007. <Dictionary.com http://dictionary.reference.com/browse/rectifier>.

&

rectifier - A worker who blends or dilutes whiskey or other alcoholic beverages. "rectifier."

The American Heritage® Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. 05 Sep. 2007. <Dictionary.com http://dictionary.reference.com/browse/rectifier>.

I think its misleading to simply have the alternating to direct current transformer definition rather than include all the definitions of rectifier.

Just throwing it out there. —Preceding unsigned comment added by 128.210.38.14 (talk) 12:28, 5 September 2007 (UTC)

Now fixed with a dab (disambiguation) page.

[edit] Don't cut and paste

Don't cut and paste content from "Allaboutcircuits.com", it's an infringement of copyright, which takes only seconds to detect. If you do add content from another source, don't drop it hodge-podge into an article; make some attempt to merge it sensibly with the organization of the article. --Wtshymanski (talk) 19:06, 12 February 2008 (UTC)

[edit] Three-Phase Bridge Rectifier

It is "Three-Phase Half Bridge Rectifier", but not "Three-Phase Bridge Rectifier". For "Three-Phase Bridge Rectifier" is need 12 diodes (Three parallel Gretz Bridges).195.208.208.111 (talk) 15:01, 15 May 2008 (UTC)

No, a full-wave 3-phase bridge needs only 6 diodes. --Wtshymanski (talk) 17:59, 15 May 2008 (UTC)

It is not a full-wave 3-phase rectifier. It is not Full Bridge rectifier. It is "3-phase Half Bridge rectifier. 3-phase Full Bridge rectifier needs 12 diodes.195.208.208.111 (talk) 09:13, 16 May 2008 (UTC)

You may be thinking of a reversing converter which uses 12 SCRs to obtain operation in all four quadrants, or possibly a 12-pulse rectifier which is fed by both star and delta windings (30 degree phase shift, 6 phases). However, a full-wave three-phase bridge rectifier only needs six diodes - I'm looking at Table 13-5 , page 13-24 in the 11th ed. of Standard Handbook for Electrical Engineers which shows a full-wave 6-pulse rectifier, using both halves of the input AC waveform. --Wtshymanski (talk) 14:21, 16 May 2008 (UTC)

It is 3-phase 3-Half Bridge rectifier, known as "star-Larionov" rectifier on 6 diodes. 3-phase 3-Full Bridge rectifier consist of 3 parallel Gratz Bridges. Every Gratz Bridge consist of 4 diodes. All 3-Full Bridge rectifier consist of 12 diodes. These rectifier is new and litle known. Yow can see russian page (article) "Rectifier" ("Выпрямитель") in russian section of Wikipedia.195.208.208.111 (talk) 15:00, 16 May 2008 (UTC)

You have the advantage over me of reading and writing both languages, but could you look at http://ru.wikipedia.org/wiki/%D0%98%D0%B7%D0%BE%D0%B1%D1%80%D0%B0%D0%B6%D0%B5%D0%BD%D0%B8%D0%B5:Full-wave_rectifier3.png

and explain why you want to use 12 diodes when 6 suffice? "Gratz bridge" and "star Larionov" are terms unknown to me. All my other references say 6 diodes are enough for a full-wave bridge., --Wtshymanski (talk) 00:38, 17 May 2008 (UTC) If you have one phase voltage you can rectify it by one Full Bridge rectifier on 4 diodes (Gratz Bridge). If you have 3-phase voltage you can rectify it by 3 Full Bridge rectifiers on 4 diods ich (3 Gratz Bridge) (12 diods). After that you can connect 3 Full Bridges parallel or secventionaly and get 2 new 3-phase rectifiers: "3 parallel Full Briges" and "3 secventional Full Bridges". After that you can see, what known 3-phase rectifier "star-Larionov" or "delta-Larionov" on 6 diodes is Half Bridge rectifiers. Rectifier "3 parallel Full Bridges" have litle internal activ resistance than "delta-Larionov" and litle temperature of cuprum of coil and litle lost of energy (fuel) on heating of cuprum of coil. From thise rectifiers only rectifier "3 secventional Full Bridge" is full-wave rectifier, anower are partitional-wave rectifiers.195.208.208.111 (talk) 09:23, 19 May 2008 (UTC)

I think you mean copper when you say cuprum. I suggest you draw out the schematic diagram of a 12-diode bridge and I think you'll see that you have several pairs of diodes effectively in parallel. Given that, you can replace the pair of diodes with a single diode and still have a full-wave bridge rectifier with only 6 diodes. Even the Russian Wikipedia page you referenced shows a 6-diode bridge and no 12-diode, 3-phase bridge at all. I believe you are mistaken. --Wtshymanski (talk) 14:03, 19 May 2008 (UTC)
Yes, I mean "copper" when I say "cuprum". Yes, if you have schematic diagram of 12-diode bridge, you can replace the pair of diods with a single diode and still have a not full-wave not bridge rectifier, but particaly-wave half-bridge rectifier with only 6 diods, known as "delta(triangl)-Larionov", thise rectifier have another internal activ eqvivalent resistance, than 12-dide bridge. Yes, Russian Wikipedia page has not schematic diagram of 12-diode bridge, but have text with 12-diode bridge. I not mistaken.195.208.208.111 (talk) 09:04, 20 May 2008 (UTC)
Sorry, I believe you are incorrect as I can find no reference that says 12 diodes are necessary for a 3-phase full-wave bridge. And I've been on the General Electric DC drives course - I'm sure they would have mentioned this! --Wtshymanski (talk) 17:57, 20 May 2008 (UTC)
Full-wave rectifiers are the 1-phase full-bridge rectifier (Gretz bridge)(4 diods), 3-phase 3 secventional full-bridge rectifier (12 diods) and the same. The 3-phase 3 half-bridge rectifier (Larionov) (6 diodes), 3-phase 3 parallel full-bridge rectifier (12 diodes) are not full-wave. In these rectifiers small parts of sinus wave are not used. You no find reference becorse thise rectifiers are new and small known. I`m sorry.195.208.208.111 (talk) 06:50, 21 May 2008 (UTC)