Electronic – Differences between 220pf 1000V capacitors

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I need to replace a popped capacitor. Externally, it looks almost like

enter image description here
(source)

except for the first letter: in my case it is R and not B.

It is in the power supply board of a TV. I would like to replace it with an equivalent one, or even with a stronger one (with the same features, but better materials), to avoid this problem to reappear.

  • Is there a difference between B 221K 1KV in the photo and my R 221K 1KV?
  • May these alternative 1 and alternative 2 be equivalent to R 221K 1KV for my purposes? Why?

As far as I know, they differ at least in the ceramic insulator, being X5F in alternative 1, and Y5P in alternative 2.

According to the Capacitor Letter Codes Table in this page, the 221K mark could refer to a 220 pF capacitace.

Edit

I am sure it is a capacitor and not an MOV because the electrical symbol of a capacitor is printed on the PCB, referred to this component.

Before thinking about modifying the circuit with a line filter, I would like to find a suitable capacitor, which is electrically equivalent to the original one.

This product suggested in the comments has a different capacitance value. In the same site, I found instead:

Both of them are 220 pF. After a first look at the datasheet, they seem to differ only as regards the external dimensions.

My question is still: from the PCB electrical perspective, given the original one marked as R 221K 1KV, are they able to replace it? Why?

Best Answer

Any cap might replace this one rated for 1kV 100 220 pF but NP0/C0G are best for ESR and temp stability. However, I would have chosen 3kV.

  • It takes a poor design, unusual conditions or a defective kV rated part to blow a 100pF cap which cannot store much energy (50 uJ) due to small capacitance. Possibly a secondary failure next to another.

    • Normally line filters should attenuate peak voltage surges.

  • Where used, may be important to know but for AC power maybe not.

    • If used with SMPS possibly for PFC compensation filter at 1.4 * line Vrms. .

  • To improve reliability, choose a cap with 3kV rating which is more standard for consumer grid impulse protection, but in truth , Power meters have only arc gaps rated for 6kV and external lightning protection is above this. This ionization takes a 1us or so to trigger.

Opinion

This means all the electronics in Florida will fail unless that device has a good line filter to reduce peak voltage below cap ratings. Or it means this why why Floridians and Mariners unplug their sensitive electronics before a lightning storm when they should be getting better line filters and OVP. (next to central Africa, Florida has one of the highest lightning strokes / year.)

enter image description here

This is a much better part but expensive, which is why it was not used.($1 /10k)

The part see rapid discharges and is used as an EMI snubber so is under very high stress as I expected.

So choose 220 pF 3kV (low ESR)

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