David,
Just curious if you've got an Cap/Inductor filter on the output of your
bridge? I don't think I have had any problems prior to adding this to the
output of the bridge, but couldn't imagine that the ripple filter would be
a cause to the problems, especially if everything runs fine without the
high discharge performance.
Terry
-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of David Rieben
Sent: Tuesday, December 12, 2017 5:25 AM
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Subject: **External Email** Re: [TCML] ARSG bridge rectifier failures
Terry,
I had pretty much the same problem with my big coil. I, too, am using a DC
motor designed for a treadmill, that is rated at like 130 VDC for the
drive of my ARSG. I was using those 1 kV, 50 amp rated FWB 'blocks' for
the rectification of the 120 VAC mains, through a 120/140 volt, 10 amp
rated variac for speed control. When I grounded the outed metallic casing
of the FWB rectifier in question, it would almost immediately get fried
once I even started to produce a spark output from my coil! Fortunately, I
had ordered a bag of 10 of these FWB units, and I discovered that when I
removed the ground from the outer casing and just allowed it to 'float',
the problem was solved.
Maybe you could explore this solution for your setup?
David Rieben
----- Original Message -----
From: "Terry Oxandale" <toxandale@xxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Sunday, December 10, 2017 9:22 PM
Subject: Re: [TCML] ARSG bridge rectifier failures
I'm having an issue with the bridge rectifiers I'm using to power a
variable speed DC motor for the rotating spark gap. When the coil is not
energized (but motor is spinning), the diode stays cool, and appears to
be
reliable. As soon as I energized the coil sufficiently to operate with
breakout, the rectifier gets a little warm, but appears to remain
reliable. With more coil performance, I notice more heating of the
rectifier. It appears, after some testing, that the lifespan of the
rectifier is inversely proportional to the power put into the coil. I
have
a voltmeter and ammeter to monitor the power to the DC motor, and there
is
nothing to indicate a problem (but these are analog meters, and may not
be
sensitive enough to see everything I'm looking for).
So far, the only variable is the coil's output (performance), so that
leads me to believe something is back-feeding or being induced into the
motor's power cord and back to the rectifier. The motor only draws about
1
or 2 amps through 90 VDC at speed, yet the rectifier is rated at 30 amps
and 600 volts. I don't run the motor at the full 90 VDC because the coil
operates best at a lower RPM, and hence a lower voltage to the motor. The
rectifier is fed through a small variac, whose output then passes through
the rectifier. The rectifier does have an LC filter to dampen the full
wave output of the rectifier. I don't know if it's the cheap Chinese Ebay
bridge rectifiers or not, but am considering building one out of some
robust diodes that I've had for years.
Any thoughts please?
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxxxxxx
https://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxxxxxx
https://www.pupman.com/mailman/listinfo/tesla
This email and any attachments are for the sole use of the intended
recipient(s) and may contain confidential information. If you receive this
email in error, please notify the sender, delete the original and all
copies of the email and destroy any other hard copies of it.
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxxxxxx
https://www.pupman.com/mailman/listinfo/tesla