Change of capacitors in voltage multiplyer

In summary, the change in capacitor value seems to have caused an increase in ripple current in the output of the voltage multiplyer.
  • #1
lucvh
9
0
Hi,

I have a supply for biasing a photomultiplyer tube in a plessey ratemeter. In the supply there is a voltage multiplyer of the Villard cascade type, with a filter after it.

The voltage multiplyer is supplied with a 9kHz supply of 300v p-p.

We replaced the original capacitors, which were a resin impregnated paper dilectric (WIMA Durolit) with a polyester dilectric capacitor. The value of capacitange has changed from 56 nF to a preferred value of 68 nF.

When we changed the capacitors over, we notived an increase in ripple current in the DC output from around 7mV to around 30mV.

Can anyone shed any light on what may have caused this?

Thanks, Luc
 
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  • #2
lucvh said:
Hi,

I have a supply for biasing a photomultiplyer tube in a plessey ratemeter. In the supply there is a voltage multiplyer of the Villard cascade type, with a filter after it.

The voltage multiplyer is supplied with a 9kHz supply of 300v p-p.

We replaced the original capacitors, which were a resin impregnated paper dilectric (WIMA Durolit) with a polyester dilectric capacitor. The value of capacitange has changed from 56 nF to a preferred value of 68 nF.

When we changed the capacitors over, we notived an increase in ripple current in the DC output from around 7mV to around 30mV.

Can anyone shed any light on what may have caused this?

Thanks, Luc

What are the ESR and ESL values for the two types and values of capacitors?
 
  • #3
I couldn't find the values in the specification sheets so i tried to measure the ESR the other day using a 9kHz square wave but i couldn't see any discernable difference between the two, although i cannot garuantee my test was completely accurate as i have never preformed it before.

I have run a few simulations on LTSpice adjusting the ESI and ESR values but it did not seem to have the magnitude of increase in ripple current that i am seeing in reality.
 
  • #4
Disregard this thread, the increase in ripple current is caused somewhere else, i checked the HT board in another ratemeter and found there to be a much lower ripple.

Now i just have to find out where the damn voltage is leaking from.
 

Related to Change of capacitors in voltage multiplyer

1. What is the purpose of a voltage multiplier?

A voltage multiplier is used to increase the voltage of an input signal, typically an AC signal, to a higher output voltage. This can be useful in various applications such as power supplies, electronic devices, and high voltage testing.

2. Why would capacitors need to be changed in a voltage multiplier?

Over time, capacitors can degrade and lose their ability to store and release electrical energy efficiently. This can lead to a decrease in the output voltage of the multiplier. Changing the capacitors can restore the multiplier's functionality and ensure a stable output voltage.

3. How often should capacitors be changed in a voltage multiplier?

The frequency of changing capacitors in a voltage multiplier depends on various factors such as the quality of the capacitors, the voltage and current levels of the input signal, and the operating conditions. It is recommended to check and replace capacitors every 1-2 years to ensure optimal performance.

4. Can any type of capacitor be used in a voltage multiplier?

No, not all capacitors are suitable for use in a voltage multiplier. The capacitors must be able to handle high voltages and have a low equivalent series resistance (ESR). Ceramic, film, and electrolytic capacitors are commonly used in voltage multipliers.

5. What are some signs that the capacitors in a voltage multiplier need to be changed?

If the output voltage of the multiplier is lower than expected, or if it fluctuates or becomes unstable, it may be a sign that the capacitors need to be changed. Other signs can include leakage, bulging, or physical damage to the capacitors. It is important to regularly monitor the performance of the multiplier and replace capacitors as needed to prevent damage to the circuit.

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