Nature of 3-phase rectifier  - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: November 29, 2018, 01:26:53 am
content: Hi there,I need a good understanding of the attached rectifier circuit.Requesting all experts to explain how it works, its function and advantage and disadvantage as well.Guide me for further development, how could we modify it.This system contains 3phase, 380V, 50Hz ac input, secondary surge protector, Aux Tr ( single phase, 380V/220V, 300VA), phase transformer( 3ph, 380v/12v,0v,12v,100VA) and a main transformer MTR( 3ph, 380V/9V,18V,800VA),SCR(1600V, 50A) bridge, DC reactor( DC 20V,20A). Rectifier output should be DC 20V 20A.Assume that the I/O control boardgives,1. PTR secondary windings phase, amplitude and rating controller.2. MTRs secondary fuse (690V, 32 A) sensing3. SCRs switching controller.4. 50mlV, 30A shunt sensing,5. GPS communication,6. RSM7. LAN8. Display....etc,9. Automatic MCCB trip.Kindly recommend me one.Related research papers, articles and ideas.Regards

author: ArthurDent
author_rank: Super Contributor
timestamp: November 29, 2018, 02:56:19 pm
content: This power supply is obviously for a large industrial application and not for home use. You should contact the company for the information you want because any misunderstanding while trying to modifying the circuit could damage a lot of components or be lethal.Here is my guess to understand what is happening but please don't mess with the supply. The (3) and (5) circles on the left show a 3-phase transformer and the 15V outputs (9V isn't used but drawn to confuse) go through 3 fuses that also have a switch function so if any one or more of the fuses open the switch circuit will send a signal to the controller to shut the supply down so the remaining phases don't try to make up for the current loss from the open phase.The RTR (19) is a reactor or inductor that probably helps reduce the ripple. Number (26) looks like reverse polarity and surge to ground protection.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 29, 2018, 03:04:48 pm
content: This is a single quadrant (non-regenerative) three phase rectifier.If you require higher current and/or voltage, the transformers, fuses, SCRs, diodes, shunt and output choke would have to be replaced.It may also be that the larger SCRs require more gate drive current, which the main board may or may not provide.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: November 30, 2018, 01:01:42 am
content: QuoteThank you, well said. lets take it as a reference. This rectifier can be use in pipe corrosion protection, meaning that cathodic protection.QuoteLet us talk for 3 and 5 circles, does the 3 winding of the transformer atcs as an inductor individualy?Could you talk about how it switched to load, SCRS allowing to switch.Talk more about what DC reactor is behaving here.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: November 30, 2018, 01:36:26 am
content: QuoteNicely recognize! If you agree should I go through a paper, take a look in the attachment.QuoteLets keep the same design at this moment. Recommend me some calculation to represent this whole system.QuoteThe circle 3 MTR gives 18V,800VA, we can calculate the secondary phase current since SCR is a current controle device, need to explain how mainboard gives current to turn it ON.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 30, 2018, 03:58:13 pm
content: I was talking aboutgate drivecurrent requirements to trigger,Igtin the SCR datasheet.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 01, 2018, 02:22:02 pm
content: Thank you sir. I understand what you wanna say. If you look at the design, you could see each phase of the secondary output of MTR is connected to each bidirectional SCR arrangement, thus positive and negative half cycle of AC signal can conduct. If you calculate the load current on secondary winding of MTR, it gives may be 1.2 amp( not sure my calculation is right or wrong). Also I have noticed one thing that secondary voltage of MTR is 18 v AC, how it would generate 20 v DV output in rectifier.At last, you didn't mention related paper does make sense for this circuit design or not.