Bleeding resistor / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Bleeding resistor

previous 1 2 3 next

Move Thread

LAN_403

Niraj Joshi

Sat Oct 16 2010, 04:58PM

Registered Member #3291 Joined: Fri Oct 08 2010, 06:06PM
Location:
Posts: 11

plz view the attached zip file .
]circuit_diagram.zip[/file]

Steve Conner

Sat Oct 16 2010, 05:41PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I don't see what the purpose of that bleeder resistor is. I can't see anything in the circuit that needs discharged. Anyone else?

It also worries me that the main contactor's coil only has one terminal. That says to me the schematic is wrong.

Proud Mary

Sat Oct 16 2010, 06:17PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

A resistor in the position indicated can have no useful function.

Patrick

Sat Oct 16 2010, 08:11PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I agree with those who say the resistor as shown can have no function, however since you think you need it so much, then use a 1M, 2.2M, 3.3M or 4.7M ohm resistor. Resistors are not value critical in most applications, aside from timing or division circuits.

I see no way to calculate a value based on what you have shown us anyway. Or why one value would be better then another.

Proud Mary

Sat Oct 16 2010, 08:36PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Patrick wrote ...

I agree with those who say the resistor as shown can have no function, however since you think you need it so much, then use a 1M, 2.2M, 3.3M or 4.7M ohm resistor. Resistors are not value critical in most applications, aside from timing or division circuits.

I see no way to calculate a value based on what you have shown us anyway. Or why one value would be better then another.

Mr Joshi, if you do decide to follow this suggestion, and connect a 1M resistor across your 5kV transformer secondary, please do make sure it has a sufficient power rating i.e. >25W - a costly part for one that isn't needed, and perhaps quite a current drain on your tester transformer too.

I suggest putting a 100G resistor across the secondary - the circuit won't even know it's there, and you'll have the satisfaction of having a bleeder resistor where your schematic says there should be one, and there will be peace in Heaven.

Adam Munich

Sat Oct 16 2010, 09:21PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Proud Mary wrote ...
100G resistor

So pretty much a spark gap.
I c wut u did thar...

Sulaiman

Sun Oct 17 2010, 01:03AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Assuming that we're talking about R24,
it's on the primary side of the transformer so it's not eht, just mains rated.

The only purpose that I can think of is to protect the contacts of the main relay against flyback/kickback voltage spikes when the contacts open.
OR if a 'Dimmerstat' is a phase-angle controler,
to supress the 'spikes' caused by that.

The value ...?
Guessing 230 Vac, something like 4k7 20 Watt or 10 kOhm 10 Watt would do.
A mains rated filament lamp would also be a good choice.

Niraj Joshi

Sun Oct 17 2010, 04:51AM

Registered Member #3291 Joined: Fri Oct 08 2010, 06:06PM
Location:
Posts: 11

@sulaiman. thank u sir. I think u solved its importance.

radiotech

Sun Oct 17 2010, 05:09AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

It appears the bleeder is across the primary of the high voltage transformer, not the secondary, and the device sems to apply a variable high voltage which is measured by the mA meter and the trip CT. The trip ct relay is in the seal-n circuit of the main relay (releases it).

Sulaiman said "The only purpose that I can think of is to protect the contacts of the main relay against flyback/kickback voltage spikes when the contacts open." This makes sense.

If that high voltage transformer is a 500 Watt, 5000 Volt unit,
with there would be a contact issue at break.

Could the "bleeder Resistor" be in fact a MOV which would make more sense.?

The main contactor coil is AC. The circuit makes sense if the other side of that coil returned to 'L' on the load side of the miniature circuit breaker.

Suggested operation.

The HV button is pushed.If the d-stat is set to zero, and the trip relay is not pulled in,and the timer link is not open, the main contactor will pull in latching via the middle contacts. Once latched
HV button doesnt have to remain pushed, and the d-stat can be advanced off zero.
When a trip happens, or timer times out, it releases.
The unit can be turned off by the miniature circuit breaker.

Overall, trying to reverse engineer this tester by just making a transformer is not a good idea

Steve Conner

Sun Oct 17 2010, 03:39PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Looks like a "Dimmerstat" is just another trade name for a variac.

(Lots of companies make variable transformers, but only General Radio are allowed to call theirs "Variacs", because they own the trademark.)

I agree that a MOV would be a good choice here. The idea is probably to stop the transformer from generating a really high spike of output voltage when the contactor is opened.

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob