varistor help needed

  • Thread starter michael nikolaou
  • Start date
M

michael nikolaou

Guest
Hi to newsgroup

I have a problem that needs some assistance.
I have a 220V 50 HZ industrial relay at 20 amps.
The arming inductor is rated at 6 watts . I need to
use a varistor as surge arrester but i don't know to
calculate the energy that will be produced and the
varistor ratings . As i understand it must be rated for
275 VAC rms.But how is the current capability related
and the energy (joules) that it is rated .Is there a rule
of thumb for such calculations ?.
Any help would be apprecciated .
 
On Mar 4, 1:14 pm, "michael nikolaou"
<michaelnikolaou_remove_...@yahoo.com> wrote:
Hi to newsgroup

I have a problem that needs some assistance.
I have a 220V 50 HZ industrial relay at 20 amps.
The arming inductor  is rated at 6 watts . I need to
use a varistor as surge arrester but i don't know to
calculate the energy that will be produced and the
varistor ratings . As i understand it must be rated for
275 VAC rms.But how is the current capability related
and the energy (joules) that it is rated .Is there a rule
of thumb for such calculations ?.
Any help would be apprecciated .
Click to expand...
It is not crystal clear that you understand the terms you are using.
Or maybe it's me....
 
"michael nikolaou" <michaelnikolaou_remove_me_@yahoo.com> wrote in message
news:gomnek$6kr$1@ulysses.noc.ntua.gr...
Hi to newsgroup

I have a problem that needs some assistance.
I have a 220V 50 HZ industrial relay at 20 amps.
The arming inductor is rated at 6 watts . I need to
use a varistor as surge arrester but i don't know to
calculate the energy that will be produced and the
varistor ratings . As i understand it must be rated for
275 VAC rms.But how is the current capability related
and the energy (joules) that it is rated .Is there a rule
of thumb for such calculations ?.
Any help would be apprecciated .
Click to expand...
Don't know the formula's but I would try a resistor in series with a
capactor connected across the relay contacts R=0.5ohms C=0.47uf rated a 400
VAC at least. (snubber circuit).
 
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