# Confused while designing copper busbars

• palash_krz
In summary, the voltage drop is negligible, and the RC time constant is not affected. The heat generated from a single capacitor discharge is proportional to I2R, and is negligible.

#### palash_krz

Hello Guys!

I was designing copper bus-bars which can withstand 1 kA current. Actually I am going to discharge a several DC capacitors into those bars. So, I was confused in the dimensioning the cross section. Is 25mm * 3mm cross section enough? I have made my calculation using 1.6 A/mm2 current density for copper. Help is badly needed.

It is straight forward to calculate the voltage (IR) drop in the copper. Is this too high for your application?

Does the copper resistance appreciably change the RC time constant of your pulse?

If the voltage drop is acceptable, what is the heating in the conductor for a single capacitor discharge? because the instantaneous heating is proportional to I2R, and the capacitor discharge current waveform I(t) is exponential, the joule heating is equal to ∫I2(t)·R·dt.

Using the specific heat for copper (0.390 joules per gram per degree C), what is the temperature rise for a single capacitor pulse?

Bob S

This reminds me of the time that I designed some buss bars used the a temperature "burn-in" chamber form a bunch of avionic navigation radios. Needless to say, thermal expansion is a big consideration.

Voltage drop is negligible, RC constant is not affected as it has very negligible resistance. Question remains is, for a rough estimate, how much cross-sectional area does it require to withstand 800A-1000A for duration of max. 3 or 4 seconds, voltages being 200/250 at 50 Hz. Thanks for your response.
(I must tell, I am going to adjust the RC constant of whole setup using a rheostat and will make it near around 2-3 or max. 4 seconds if necessary. My setup will work if i reach 2 seconds.)

For rough calculation of temperature rise of copper,
calculate the energy stored in the capacitor,
then using this energy calculate the temperature rise of the copper.

## 1. How do I determine the appropriate size for a copper busbar?

The size of a copper busbar is determined by the current carrying capacity needed for the circuit. This can be calculated using the ampacity tables provided by the National Electric Code (NEC) or by using online calculators specifically for copper busbars.

## 2. What is the best material for a copper busbar?

Copper is the most commonly used material for busbars due to its high conductivity and low resistance. Other materials such as aluminum and silver can also be used, but they may not have the same level of performance as copper.

## 3. How do I prevent overheating in copper busbars?

Overheating in copper busbars can be prevented by ensuring proper ventilation and using the correct size for the current load. It is also important to check for any loose connections or corrosion that can lead to increased resistance and heating.

## 4. Can I bend or shape copper busbars?

Yes, copper busbars can be bent or shaped to fit into different configurations. However, it is important to use proper tools and techniques to avoid damaging the busbar or affecting its performance.

## 5. How do I connect copper busbars to other components?

Copper busbars can be connected to other components using various methods such as bolted connections, welded connections, or soldered connections. The method chosen will depend on the specific application and the size of the busbar.