Stacking mosfets

[Arpit]

Hi, a design calls for some mosfets rated at about 20 amps and 500
volts IRFP460 to be precice. But the mosfets I have access to only are
rated at 200 volts, though have a substantial amperage rating. WOuld
it be possible to stack them somehow in series or something to
increase the effective voltage rating of the whole bunch?

 

[Mike Harding]

On Mon, 01 Sep 2003 22:21:07 GMT, Arpit
<DONTSPAMMEF00Lneko4@dodo.com.au> wrote:

Hi, a design calls for some mosfets rated at about 20 amps and 500
volts IRFP460 to be precice. But the mosfets I have access to only are
rated at 200 volts, though have a substantial amperage rating. WOuld
it be possible to stack them somehow in series or something to
increase the effective voltage rating of the whole bunch?

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

What are you making?

Mike Harding

 

[Arpit]

On Tue, 02 Sep 2003 08:43:45 +1000, Mike Harding
<mike_harding1@hotmail.com> wrote:

On Mon, 01 Sep 2003 22:21:07 GMT, Arpit
DONTSPAMMEF00Lneko4@dodo.com.au> wrote:

Hi, a design calls for some mosfets rated at about 20 amps and 500
volts IRFP460 to be precice. But the mosfets I have access to only are
rated at 200 volts, though have a substantial amperage rating. WOuld
it be possible to stack them somehow in series or something to
increase the effective voltage rating of the whole bunch?

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

What are you making?

Induction heater

http://dave.golfbuddys.com/hvguy/new/2500Wheater/schematic.GIF

Mike Harding

 

[Arpit]

On Tue, 02 Sep 2003 08:43:45 +1000, Mike Harding
<mike_harding1@hotmail.com> wrote:

On Mon, 01 Sep 2003 22:21:07 GMT, Arpit
DONTSPAMMEF00Lneko4@dodo.com.au> wrote:

Hi, a design calls for some mosfets rated at about 20 amps and 500
volts IRFP460 to be precice. But the mosfets I have access to only are
rated at 200 volts, though have a substantial amperage rating. WOuld
it be possible to stack them somehow in series or something to
increase the effective voltage rating of the whole bunch?

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

It'll probably only run off 315 volts or so, ie 240 volts rectified,
and im used to that, thanks for the concern tho , makes me feel wanted

What are you making?

Mike Harding

 

[Phil Allison]

"Mike Harding" <mike_harding1@hotmail.com>

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

** Arpit is a 16 year old.



............ Phil

 

[Victor Lamb]

"Phil Allison" <philallison@optusnet.com.au> wrote in message
news:3f53d782$0$6529$afc38c87@news.optusnet.com.au...

"Mike Harding" <mike_harding1@hotmail.com

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.



** Arpit is a 16 year old.

So? What is your point? Many of us got into electronics when we were young.

All the more reason to provide information and assistance to this person.
It's better that they got the benefit of the experience of the people here,
rather than put themselves at risk of injury, shock or causing damage to
equipment.

If I knew something about the use of MOSFET's in power applications, then I
would tell Arpit something useful. Unfortunately I don't.

Vic.

 

[Phil Allison]

"Victor Lamb" <vltemp@ihug.NO.com.SPAM.au> wrote in message
newsgU4b.77634$bo1.48610@news-server.bigpond.net.au...

"Phil Allison" <philallison@optusnet.com.au> wrote in message
news:3f53d782$0$6529$afc38c87@news.optusnet.com.au...

"Mike Harding" <mike_harding1@hotmail.com

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.



** Arpit is a 16 year old.


So? What is your point?

** The danger to him.

All the more reason to provide information and assistance to this person.

** You must be a absolute idiot.

It's better that they got the benefit of the experience of the people
here,
rather than put themselves at risk of injury, shock or causing damage to
equipment.

** Huh ?

You are worse than I tought.

If I knew something about the use of MOSFET's in power applications, then
I
would tell Arpit something useful. Unfortunately I don't.

** Thank god for that.



............ Phil

 

[Mike Harding]

On Tue, 02 Sep 2003 03:58:57 GMT, Arpit
<DONTSPAMMEF00Lneko4@dodo.com.au> wrote:

On Tue, 2 Sep 2003 09:34:46 +1000, "Phil Allison"
philallison@optusnet.com.au> wrote:


"Mike Harding" <mike_harding1@hotmail.com

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

** Arpit is a 16 year old.

Oh god, I knew I shouldnt have let slip my age. Ah well, I guess you
are only saying it out of concern for me

To be fair to Phil I think that was exactly his reasoning.

And he's right.

That circuit is intended to run from 120V AC, if you
connect it to 240V the voltage between "+350v"
and "Power" will be closer to 700V! So you had
better think carefully about the voltage ratings of
BR2 and C15/C16. Not to mention all the other
HV stuff on the secondary of T2 - and you'll need
to upgrade (not downgrade) those MOSFETs.

And keep in mind that with C15/C16 at 4700uF
and 700V touching those is probably instant death.

Arpit I fully understand the attraction of these sorts
of circuits to you (we've all been there) but messing
with that sort of stuff when you don't understand
it may well kill you. Leave the high voltage stuff
alone for now you need a lot more knowledge
before you can work with it safely.

Mike Harding

 

[Arpit]

On Tue, 02 Sep 2003 17:03:59 +1000, Mike Harding
<mike_harding1@hotmail.com> wrote:

On Tue, 02 Sep 2003 03:58:57 GMT, Arpit
DONTSPAMMEF00Lneko4@dodo.com.au> wrote:

On Tue, 2 Sep 2003 09:34:46 +1000, "Phil Allison"
philallison@optusnet.com.au> wrote:


"Mike Harding" <mike_harding1@hotmail.com

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

** Arpit is a 16 year old.

Oh god, I knew I shouldnt have let slip my age. Ah well, I guess you
are only saying it out of concern for me

To be fair to Phil I think that was exactly his reasoning.

And he's right.

That circuit is intended to run from 120V AC, if you
connect it to 240V the voltage between "+350v"
and "Power" will be closer to 700V! So you had
better think carefully about the voltage ratings of
BR2 and C15/C16. Not to mention all the other
HV stuff on the secondary of T2 - and you'll need
to upgrade (not downgrade) those MOSFETs.

Yeah, I saw that, I'm just gonna run it off off my capacitor bank i
made a couple of months ago- about 1500uf at 315 volts.

And keep in mind that with C15/C16 at 4700uF
and 700V touching those is probably instant death.

Arpit I fully understand the attraction of these sorts
of circuits to you (we've all been there) but messing
with that sort of stuff when you don't understand
it may well kill you. Leave the high voltage stuff
alone for now you need a lot more knowledge
before you can work with it safely.

:/

What are some good books about the subject?

>Mike Harding

 

[The real Andy]

"Arpit" <DONTSPAMMEF00Lneko4@dodo.com.au> wrote in message
news:qsj8lvcsua4v13kdfbl58trlrjj6io9n1g@4ax.com...

On Tue, 02 Sep 2003 17:03:59 +1000, Mike Harding
mike_harding1@hotmail.com> wrote:

On Tue, 02 Sep 2003 03:58:57 GMT, Arpit
DONTSPAMMEF00Lneko4@dodo.com.au> wrote:

On Tue, 2 Sep 2003 09:34:46 +1000, "Phil Allison"
philallison@optusnet.com.au> wrote:


"Mike Harding" <mike_harding1@hotmail.com

In a word; No.

500V is a serious voltage, unless you _really_ know
what you are doing use the specified parts and don't
mess with the design.

** Arpit is a 16 year old.

Oh god, I knew I shouldnt have let slip my age. Ah well, I guess you
are only saying it out of concern for me

To be fair to Phil I think that was exactly his reasoning.

And he's right.

That circuit is intended to run from 120V AC, if you
connect it to 240V the voltage between "+350v"
and "Power" will be closer to 700V! So you had
better think carefully about the voltage ratings of
BR2 and C15/C16. Not to mention all the other
HV stuff on the secondary of T2 - and you'll need
to upgrade (not downgrade) those MOSFETs.


Yeah, I saw that, I'm just gonna run it off off my capacitor bank i
made a couple of months ago- about 1500uf at 315 volts.

Or do this (be careful), please exuse crude drawing and please heed all
warning others have given, such as please do not attempt this at home - use
it as a reference only.

bridge
Live -----------/\ +----+------- 340Vdc
/ \ | |+
+-<- +>------+ --- 4700uF
| \ / --- 200V
Neutral -----)---\/ |+
| --- 4700uF
| --- 200V
| |
+------------------+--------- 0V

I also like to put bleeder resistors across each cap. Helps you not to get a
belt after the unit has been sitting around.

And keep in mind that with C15/C16 at 4700uF
and 700V touching those is probably instant death.

Arpit I fully understand the attraction of these sorts
of circuits to you (we've all been there) but messing
with that sort of stuff when you don't understand
it may well kill you. Leave the high voltage stuff
alone for now you need a lot more knowledge
before you can work with it safely.

I was tought to always work with one hand behind my back!!

:/
What are some good books about the subject?

Try getting hold of some Workplace Health and Saftey videos before you
attempt anything. If they don't make you vomit, they will teach you to be
extremely careful.

 

[Terry Hulme]

The bleeder resistors will also keep the emf across each cap balanced
during inital charging, on turn-on which might stop a cap from
blowing.
with regard to the original post, you can stack mosfets in parallel to
increase the current capability [not the voltage] but it gets messy
when a mosfet blows, a lot of work needed when replacing all the
mosfets and checking all drive circuitry.
regards Terry
On Tue, 2 Sep 2003 19:13:08 +1000, "The real Andy"
<ihatehifitrolls@yahoo.com.au> wrote:

Or do this (be careful), please exuse crude drawing and please heed all
warning others have given, such as please do not attempt this at home - use
it as a reference only.

bridge
Live -----------/\ +----+------- 340Vdc
/ \ | |+
+-<- +>------+ --- 4700uF
| \ / --- 200V
Neutral -----)---\/ |+
| --- 4700uF
| --- 200V
| |
+------------------+--------- 0V

I also like to put bleeder resistors across each cap. Helps you not to get a
belt after the unit has been sitting around.