Cause of VFD Damage.

CR4 Home | Electrical Engineering | Electrical Engineering

13 comments

Rate

salahuddin zia Power-User Join Date: Feb 2010 Posts: 164	Cause of VFD Damage. 06/12/2013 3:07 AM
	Dear Honorable Members: A plant has faced a serious problem (i.e. damaging of the Inverter) which I am sharing with all of you with a hope that someone will help in tracing the root cause. The VFD drive( Vacon type NXP 1900-6) of 1.8MWatt. which needs 690Volts,and is being supplied by 11,000 / 720V transformer and this transformer is only dedicated for this drive which is for one Extruder motor. The VFD got damaged and as per Plant version the motor (1.8 Mw) is in healthy condition. The plant has its own generation ( 11,000/ 0.4 Kv) through gas generators Last thirty alarms recorded before VFD was damaged are as follows 17 times alarm number is 66. That is about main contactor. 12 times alarm number is 63, that is about emergency stop. 1 time alarm number is 29, that is about thermistor On checking the Inverter, four resistors of the rectifier are showing open circuit, as per supplier they are concealed resistor with fuse inside, so fuse or resistor is burnt; it is not clear. As the machine supplier can check on line the data, he might has seen overvoltage alarm on line that is why he thinks there were spikes of high voltage from Transformer which resulted in this damage. The Plant maintenance Department wants to know whether the cause of the damage was due to spikes of high voltage generated from the transformer or some other relevant cause
	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!

Good Answers:

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

#4 "Re: Cause of VFD Damage." by JRaef on 06/12/2013 9:45 AM (score 3)

PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: Cause of VFD Damage. 06/12/2013 4:06 AM
	<...The Plant maintenance Department wants to know whether the cause of the damage was due to spikes of high voltage generated from the transformer or some other relevant cause...> The forum wants to know why thirty arlarms were ignored prior to the damage taking place. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
	Register to Reply

PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#2 In reply to #1 Re: Cause of VFD Damage. 06/12/2013 5:59 AM
	...because one of the possibilities for relevant causes is that none of these alarms was attended on occurrence. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
	Register to Reply

lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#3 Re: Cause of VFD Damage. 06/12/2013 8:56 AM
	Someone who actually knows the VFD, and has data to substantiate "that overvoltage alarm on line that is why he thinks there were spikes of high voltage from Transformer which resulted in this damage" has told you what the problem is!!!! They are the experts here. For you to come to an anonymous forum and ask us to analyze your skimpy data is folly. Do what the experts advise.
	Register to Reply

JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#4 Re: Cause of VFD Damage. 06/12/2013 9:45 AM
	Best guess based on slim evidence presented: Ignore the thermistor trip, that means your motor got hot and the drive protected it. The Emergency Stop alarms are usually just a way or recording when someone used the E-Stop function to shut it down. But given that your quantity of E-Stop alarms is nearly equally to your contactor alarms, then that the damage was in the pre-charge resistors of the rectifier, it possibly points to an inappropriate use of the E-Stop routine to stop the motor. Whenever you cycle main line contactors on a VFD, the capacitors must re-charge and there is a quick but very high inrush of charging current into them which can damage the front end rectifier components. So the drive has a pre-charge resistor in series with the caps as a current limiter, then once the caps are charged, a contactor shorts the resistors out. Smaller drives now just use an NTC resistor, but large drives like this still use a contactor. Cycling power a lot by opening a main line contactor can stress those resistors inappropriately and cause them to fail. It could also be that the contactor mentioned in the alarms is not a main line contactor, but the pre-charge contactor. If that fails, the resistors are left in the circuit and they quickly burn out. __________________ All I every really wanted to be, was... A LUMBERJACK!.
	Register to Reply Good Answer (Score 3)

No more Good Answers.

salahuddin zia Power-User Join Date: Feb 2010 Posts: 164	#7 In reply to #4 Re: Cause of VFD Damage. 06/13/2013 1:37 AM
	Dear Mr. JRaef Sorry i can,t find suitable words to thank-you Mr.JRaef for your support. The techical detail will definitely help the plant alot. Hoping by flipping through your comments they in future will save the VFDs.
	Register to Reply

dhayanandhan Guru Join Date: May 2008 Location: CHENNAI, TAMIL NADU, INDIA. Posts: 1851 Good Answers: 65	#5 Re: Cause of VFD Damage. 06/12/2013 12:27 PM
	The VFD- is it of 6 Pulse or 12 Pulse.? For Higher Capacity - it should be of 12 Pulse. Pl. check up this. WHAT ABOUT EARTHING.? The transformer - Secondary is it Delta wound or Star wound.? DHAYANANDHAN.S
	Register to Reply

salahuddin zia Power-User Join Date: Feb 2010 Posts: 164	#8 In reply to #5 Re: Cause of VFD Damage. 06/13/2013 3:07 AM
	The VFD is 6 pulse. Transformer Rating: Rated Power------ 2500Kva Vector Group:-------------------------DYn5 / Dd0 Rated Voltage ------------------------HV (11000V), LV (720 / 720 ) Rated Current-------------------------- HV ( 131.2 A), LV (1002.4/ 1002.4 A ) Earthing as per plant report is Ok.
	Register to Reply

dhayanandhan Guru Join Date: May 2008 Location: CHENNAI, TAMIL NADU, INDIA. Posts: 1851 Good Answers: 65	#9 In reply to #8 Re: Cause of VFD Damage. 06/13/2013 5:09 AM
	Pl. provide the details of EARTHING for the VFD APPLICATION. You have referred "EARTHING ASPER PLANT REPORT IS OK" is a GNERAL and RELATIVE TERM. DHAYANANDHAN.S
	Register to Reply

salahuddin zia Power-User Join Date: Feb 2010 Posts: 164	#10 In reply to #9 Re: Cause of VFD Damage. 06/17/2013 1:25 AM
	Sorry for replying you so late the reason being i just got hold of the Earthing test report which i am forwarding to you.
	Register to Reply

dhayanandhan Guru Join Date: May 2008 Location: CHENNAI, TAMIL NADU, INDIA. Posts: 1851 Good Answers: 65	#11 In reply to #10 Re: Cause of VFD Damage. 06/17/2013 5:10 AM
	Dear Mr.salahuddin zia, Thank you for your response. What you have posted is the values in OHM. What I am informing is to send the Single Line Diagram of the Earting System with the copper/aluminum flat. For VFD earthing recommended/advised area of EARTHING FLAT is twice or more and its proper securing is a MUST. DHAYANANDHAN.S
	Register to Reply

salahuddin zia Power-User Join Date: Feb 2010 Posts: 164	#12 In reply to #11 Re: Cause of VFD Damage. 06/18/2013 2:37 AM
	I have requested the plant management to pass on the details you have asked for,and they will be posted as soon as i have them at my end. To be honest the chances are slim.
	Register to Reply

nssudhakar1968 Participant Join Date: Dec 2009 Posts: 3	#13 In reply to #11 Re: Cause of VFD Damage. 09/24/2013 7:49 AM
	Dear Mr Dayanandhan It has been observed of late, that higher size VFD's are provided with a Delta/ Star transformer on the VFD input, with the star point left unearthed. Can you kindly explain the reason for the same?
	Register to Reply

sivaa Commentator Join Date: Aug 2008 Posts: 82	#6 Re: Cause of VFD Damage. 06/12/2013 1:21 PM
	Load for Extrusion motor - as per OEM recommendations and recent utilisation are to be tabulated in your end so that we may track parallel indications with failure alarms . If not so, aging of components could be claimed for . Sensing circuitry of VFD is good and motor is healthy . Re-occurance or nature of rectification should lead further .
	Register to Reply

Good Answers:

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

#4 "Re: Cause of VFD Damage." by JRaef on 06/12/2013 9:45 AM (score 3)

Copy to Clipboard

Users who posted comments:

dhayanandhan (3); JRaef (1); lyn (1); nssudhakar1968 (1); PWSlack (2); salahuddin zia (4); sivaa (1)

	Got Something to Say?
	Ask a Question Start a Discussion

	Search this Forum
	Electrical Engineering: Go

CR4 Sections

	Aerospace
	BioMech & BioMed
	Chemical & Material Science
	Civil Engineering
	Communications & Electronics
	Education and Engineering Careers
	Electrical Engineering
	General Discussion
	Instrumentation
	Manufacturing
	Mechanical Engineering
	New Technologies & Research
	Software & Programming
	Sustainable Engineering
	Transportation

	Site Directories
	Forum Directory Blog Directory User Group Directory RSS Feeds CR4 Rules of Conduct CR4 FAQ Site Glossary Who's Online (48 right now) Show Members

Comments Format:

Subscribe to Discussion:

Rating Vote:

Good Answers:

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Re: Cause of VFD Damage.

Good Answers:

Users who posted comments:

Got Something to Say?

Search this Forum

CR4 Sections

Site Directories