# Maximum voltage on coaxial cable?

• cdummie
In summary: And the point is chosen in such way that the electric field is the same at that point whether it's dielectric or free-space. This means that the dielectric constant is the same as free-space. In summary, the problem is asking for the maximum voltage that a coaxial cable, with a height of L and filled with a homogeneous and linear dielectric, can handle if the maximum electric field is 3MV/m and the inner radius is 2cm and the outer radius is 2.72 times the inner radius. The cable is filled with dielectric to a certain point, and the electric field is the same at this point whether it is in the dielectric or free space. This suggests that the dielectric constant is the
cdummie

## Homework Statement

How to determine maximum voltage that coaxial cable, whose height is L and is filled with dielectric in such way that E is the same in the dielectric and in the part of the cable that isn't filled with dielectric (only vacuum),can handle if i have maximum electric field that is E=3MV/m, and i have inner radius a=2cm and outer b=2.72a. Dielectric is homogeneous and linear.

## The Attempt at a Solution

I tried like this U=∫E*dl but since i know exact value of Emax and no data for εr and Qmax i can't solve this.

cdummie said:

## Homework Statement

How to determine maximum voltage that coaxial cable, whose height is L and is filled with dielectric in such way that E is the same in the dielectric and in the part of the cable that isn't filled with dielectric (only vacuum),can handle if i have maximum electric field that is E=3MV/m, and i have inner radius a=2cm and outer b=2.72a. Dielectric is homogeneous and linear.

## The Attempt at a Solution

I tried like this U=∫E*dl but since i know exact value of Emax and no data for εr and Qmax i can't solve this.

The part I bolded looks like a typo -- is it?

The breakdown voltage will depend on the breakdown voltage of the dielectric and the spacing between the conductors. If you have the maximum electric field and the separation (and the dielectric constant), you should be able to calculate the breakdown voltage.

Last edited:
berkeman said:
The part I bolded looks like a typo -- is it?

The breakdown voltage will depend on the breakdown voltage of the dielectric and the spacing between the conductors. If you have the maximum electric field and the separation (and the dielectric constant), you should be able to calculate the breakdown voltage.

I don't know what you mean, bolded part is correct b=2.72a, that's the given value. I don't have the value for the dielectric constant, if i had i could easily find Qmax and then find U using E expressed with Qmax. The problem is that i don't have dielectric constant.

cdummie said:
I don't know what you mean, bolded part is correct b=2.72a, that's the given value. I don't have the value for the dielectric constant, if i had i could easily find Qmax and then find U using E expressed with Qmax. The problem is that i don't have dielectric constant.

Oh, I see now. The outer radius is given as a multiple of the inner radius -- that's what was confusing me about the dimensions.

The rest of the question is a bit confusing as well. Is there a figure that you can post? What does it mean when it seems to say

cdummie said:
and is filled with dielectric in such way that E is the same in the dielectric and in the part of the cable that isn't filled with dielectric

That makes no sense unless the dielectric constant is the same as free space. Is the problem copied word-for-word?

berkeman said:
Oh, I see now. The outer radius is given as a multiple of the inner radius -- that's what was confusing me about the dimensions.

The rest of the question is a bit confusing as well. Is there a figure that you can post? What does it mean when it seems to say
That makes no sense unless the dielectric constant is the same as free space. Is the problem copied word-for-word?
It's not completely filled with dielectric, it's filled with dielectric to the some point and rest is free-space.

## 1. What is the maximum voltage that a coaxial cable can handle?

The maximum voltage that a coaxial cable can handle depends on various factors such as the quality of the cable, its length, and the type of insulation used. Generally, most standard coaxial cables can handle voltages up to 3000 volts.

## 2. What happens if the maximum voltage on a coaxial cable is exceeded?

If the maximum voltage on a coaxial cable is exceeded, it can cause the cable to overheat, leading to damage or failure. This can also result in electrical arcing, which can be a fire hazard and cause serious damage to equipment.

## 3. Is there a difference in the maximum voltage for different types of coaxial cables?

Yes, there can be a difference in the maximum voltage for different types of coaxial cables. For example, RG-6 cables used for cable and satellite TV installations have a maximum voltage of 300 volts, while RG-11 cables used for high-speed data transfer can handle up to 5000 volts.

## 4. Can the maximum voltage on a coaxial cable be increased?

No, the maximum voltage on a coaxial cable cannot be increased beyond its maximum limit. Attempting to increase the voltage can cause serious damage to the cable and any connected equipment.

## 5. How can I determine the maximum voltage for a specific coaxial cable?

The maximum voltage for a specific coaxial cable can usually be found in the cable's specifications provided by the manufacturer. It is important to always check the specifications before using a cable to ensure it can handle the required voltage for your application.

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