If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #18516
Joined: Sat May 18 2013, 09:09AM
Location: Lancashire, UK
Posts: 38
Rooting around the scrap pile at work i've come across a busted 7.5kw inverter.
Its casing has a nice heatsink and a capacitor module and i'm wondering if they'd be suitable for the DC bus on my DRSSTC.
The module has 6 nichicon caps rated at 1000uf 400v, as far as i can make out they're arranged in a 2x3 series parallel array, to give 1500uf at 800v. I guess ofcourse that i could remove them from the PCB and rearrange them into a different arrangement. What am i looking for to find out if these caps are suitable for the DC bus, and how much capacitance do i need here? Similar coils seem to use around 3-4000uf. Are there other specs i need to find from these caps to know if they're suitable?
They appear to be "GU" series caps, but the nichicon website doesnt list a 1000uf 400v cap in that range.
Its for an 4x18" DRSSTC with a full bridge of 60n60 bricks.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
I consider Nichicon caps to be good quality, knowing how much they have been aged in service is difficult. (lots of experienced guys at work - no clear consensus) First, remove the capacitors to check for erosion of the pcb or signs that the vent (pip) has operated = fail. weight (presumably electrolyte) loss = fail (e.g. 1 of 6 feels 'light') high leakage current or capacitance loss can indicate a 'weak' unit, high esr is a good indicator of end of service life esr meters are a bit specialist, so if a cap looks and feels ok, it probably is.
At work, our standard repair for drives (inverters) is to replace all small aluminium electrolytics and test the Bus Caps. Warranties are bad for our business but drives run for decades, during which time the same drive may be repaired more than once but the Bus Caps generally outlive the drives.
check and clean the bus cap pcb.
P.S. the output stages are all fairly similar, pwm relying on motor (or additional) inductance to produce sine wave motor current. Some have interesting gate drivers.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
high leakage current or capacitance loss can indicate a 'weak' unit,
Don't get too uptight about an initially high 'leakage' current. Electrolytics, especially if they've been sitting around a long time, and especially if you're charging them to a higher voltage than they were used for before, can take quite a high reforming current for quite a while before they settle down. Though if one is much longer than the other 5, it's not a good sign for that one.
Registered Member #18516
Joined: Sat May 18 2013, 09:09AM
Location: Lancashire, UK
Posts: 38
Thanks.
I dont really know what went wrong with this inverter, so i guess the caps may or may not be knackered. The electronics guy reconned at least one of the IGBT's had popped. PCB was dated 2007, so its not new, but not mega ancient either.
I tried sticking a multimeter on capacitance mode across the PCB terminals, but it didnt do anything, however i noted that there appear to be a pair of resistors soldered across the PCB planes, so i guess those were probably causing issue with the readings.
The PCB itself is in perfect condition, and the caps dont look swolen or damaged at all, so i'm hoping they're ok. Even if i got 3 or 4 of the 6 working that would be fine i think.
I'm off on holiday next week, but when i'm back in i will try to desolder the caps from the board and test them. Not sure if we have an ESR meter, might be one knocking around.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
DC Bus Caps
