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Capacitors type X and Y Problems

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Saeedk9574

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Hello every one, I want to make a 24V 10A SMPS, based on the schematic found on the Internet, I need two mkt 100nf x2 275v capacitors in the line filter. The problem is I can not find exactly this cap in the market. I have these options in the market:
1. MKT 150nf 275v x2,
2. MKT 100nf 630v (in this on it is not mention whether it is x2 or not)
3. MKT 100nf 250v x2

In addition, I need two x1 y1 2.2nf 400v in the line filter, A power Supply that I opened, used this model: JN222M 400V Disc Capacitor 400V. but again I can not find it in the market, do you have alternative option for this one?
reverz45b.png
 
Hi,

Given information: 24V/10A is useless for the given capacitor question.
--> what´s important: 220V/ 50Hz

Capacitors:
1) may work. draws a bit more capacitive current
2) ... if not marked "X2" then don´t use it. You violate safety regulations and thus in case of fire or somehow hurt persons you may be held responsible.
(most probably the "630V" is maximum/peak (DC voltage), and not the RMS voltage (often marked with a "~") as given by the other X2 capacitors.
3) While technically not false ... you need to calculate with mains voltage fluctuatins, noise and bursts on the mains line. Thus it´s recommended to use a higher voltage rated capacitor.

100nF/X2 with 275V (or higher) are not usual. Should be easy to find.
Maybe ask some collegues, or look for one in old devices.

Klaus
 
Thanks for sharing your information, so among these three option the first one is better.
 
D.A.(Tony)Stewart said:
X1 and Y1 are better in lightning prone areas.
Click to expand...
X and Y capacitors are "safety ratings".
Their special design prevents fire / electrical shock on capacitor failure.

Do an internet search on "X Y safety capacitors explained"

In my region there is almost zero over ground power distribution, all is under ground. Not lightning prone at all.
Still one needs to use safety capacitors and they need to fulfill their safety requirements.

Klaus
 
KlausST said:
X and Y capacitors are "safety ratings".
Their special design prevents fire / electrical shock on capacitor failure.

Do an internet search on "X Y safety capacitors explained"

In my region there is almost zero over ground power distribution, all is under ground. Not lightning prone at all.
Still one needs to use safety capacitors and they need to fulfill their safety requirements.

Klaus
Click to expand...

Thanks, Klaus I learned about XY caps 25 years before the internet existed.

Near Toronto, there are many overhead trunk lines although residential is underground in my 70's development area.
Underground XLPE cables are coaxial grounded and the Poly cable is radiated with EHF to crosslink the plastic to reduce moisture absorption.
However transients may still occur on underground XLPE cables due to partial discharge (PD) after 50 yrs of aging. I have noticed every spring only the ground was frozen and was thawing out, I would get at least 1 momentary power shutdown, which I suspected was an arc from PD that tripped the distribution breaker. This year power technicians were replacing all the insulator bushings in the plugs of the residential padmounts. Later this summer they will excavate and will pump fresh silicone into the underground cables to restore their insulation value.

When I was last in Florida every power line pole in the neighbourhood had a sharp tungsten antenna on top of every pole for lightning diversion to ground.
 
Last edited:
KlausST said:
X and Y capacitors are "safety ratings".
Their special design prevents fire / electrical shock on capacitor failure.

Do an internet search on "X Y safety capacitors explained"

In my region there is almost zero over ground power distribution, all is under ground. Not lightning prone at all.
Still one needs to use safety capacitors and they need to fulfill their safety requirements.

Klaus
Click to expand...
About main and drive transformer, and the inductor after main transformer (mentioned 15 turn in 15 turns), How can I find them in the market which qualities and details should I look for?
 
Saeedk9574 said:
About main and drive transformer, and the inductor after main transformer (mentioned 15 turn in 15 turns), How can I find them in the market which qualities and details should I look for?
Click to expand...
I´d start with reading the IC datasheet. It usually tells you all you need to know to design a whole circuit.... Including how to calculate part values and part specifications.

Most IC manufacturers provide additional informations on how to design: like: application notes, design notes, evaluation boards, simulation tools....
Just look at their (product) internet site.

Klaus
 
KlausST said:
I´d start with reading the IC datasheet. It usually tells you all you need to know to design a whole circuit.... Including how to calculate part values and part specifications.

Most IC manufacturers provide additional informations on how to design: like: application notes, design notes, evaluation boards, simulation tools....
Just look at their (product) internet site.

Klaus
Click to expand...
Although I have read datasheet, I could not understand how to find the appropriate transformers and inductor for this 24v 10A SMPS
 

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