ABT Rectifier - CR4 Discussion Thread

HOME | CR4 | Electrical Engineering | Electrical Engineering

3 comments

loyd Associate Join Date: Mar 2011 Posts: 48	ABT Rectifier 01/28/2012 11:58 AM
	Dear Engineers, May be the question I am asking is looks silly,but i am confused about it so please give clarification. In 3 phase rectifier we are using 6 thyristor and if we give 415v ac it will come around 560v dc at output when we measure with our voltmeter. Now if one of this 6 thyristor was not getting firing signal or it was bad (not conducting) then output voltage when we measure with voltmeter will show 560 v dc only? Is this right, or is there any changes in o/p voltage? As our voltmeter measures peak value. How we can find out there is problem in 1 thyristor? Thank you
	Register to Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Join CR4, The Engineer's Place for News and Discussion!

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

#1 "Re: ABT Rectifier" by MUKULMAHANT on 01/29/2012 12:18 AM (score 2)

Rated a 'Good Answer' with a score of 2

2

MUKULMAHANT Guru Join Date: Dec 2006 Location: Long.92E,Lat.26N Posts: 1336 Good Answers: 14	#1 Re: ABT Rectifier 01/29/2012 12:18 AM
	Simple way will be thus: Filter the harmonics out of a "DC Volt-Out " measuring circuit--branching from Rectified output-- which is loaded with a constant heavy resistive load RL . You are suspecting that 1 of the 6 -not working: Take the reading=V11.RL is the load. Now disconnect any one thyristor. Load as before .Take the reading=V12.RL is the load Likewise 4 more times --take readings V13>>V16-all tested. RL is the load each time . Now see which being disconnected made no difference. That is the FAULTY one .
	Register to Reply Good Answer (Score 2)

No more Good Answers.

Haajee Guru Join Date: Feb 2006 Posts: 1763 Good Answers: 6	#2 Re: ABT Rectifier 01/29/2012 8:29 AM
	In that case only 2 Φs are conducting in full wave. It will give as much output but ripple may increase on full load. If you have a CRO try to measure ripple on both conditions [disconnect filter] See Rectifier
	Register to Reply

kwcharlie Power-User Join Date: Jan 2010 Location: Houston off/on-shore @ Oil Patch Posts: 225 Good Answers: 2	#3 Re: ABT Rectifier 01/30/2012 6:55 PM
	You won't see much voltage output difference at all when one diode opens, you will see whatever the rectifier is powering get VERY hot, then you need a scope to find which is bad/not-firing. Now if you have a blown fuse DON'T replace it until you check if one of the diodes/SCR's are still shorted, then you won't have to use a scope to find the open/not-firing one. in the real world the voltage drop isn't useful for troubleshooting 6 diode circuits __________________ Why do they make manhole covers round? so they won't fall in [before asking "Who is John Galt?"]
	Register to Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Join CR4, The Engineer's Place for News and Discussion!

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

#1 "Re: ABT Rectifier" by MUKULMAHANT on 01/29/2012 12:18 AM (score 2)

Copy to Clipboard

Users who posted comments:

Haajee (1); kwcharlie (1); MUKULMAHANT (1)