AC needs more insulation than DC for same voltage level because the peak value of the AC is greater than DC for the same voltage level. This is a very important and frequently asked question is that Why AC needs more Insulation than DC for the same Voltage Level? Sometimes this question is asked as Why DC needs less Insulation than AC for the same Voltage Level? The answers of both questions are the same. Read the full Article to know the answer in detail explanation.

## The Reasons Why AC needs more Insulation than DC

• The peak value of AC is greater than DC for the same voltage level. That means a 230V DC supply has constant 230V voltage but in a 230V AC supply, Voltage reach ulto 250V. In case of AC, we always consider an average value or RMS value.
• There is Hysteresis loss occurs in case of AC which depends upon the frequency of the AC. But DC has not frequency so there is no chance of hysteresis loss.
• There are capacitance and inductance effect occurs in case of AC but there is no capacitance and inductance effect occurs in case of DC.

Detail Explanation:

(1) We all know that we generally use the RMS(Root Means Square) value for AC. The AC voltage rating in any electrical equipment indicates the RMS value. We use 230V single phase AC for our domestic purpose which also indicates the RMS value.

The RMS value and peak value of AC are different because AC changes the magnitude of voltage.
As DC is constant, there are no changes in the magnitude of the voltage so the RMS value and the peak value is the same.

As you see in the above figure we have taken the same AC and DC voltage waveform that is 230V. You can see the difference between the peak values of AC and DC.

The peak value of DC is 230V
The peak value of  AC is = 230 × √2 = 325.27V

So you can see there is a very big difference between the RMS value and the peak value of 230V AC. So naturally, the potential stress will be high.

The more voltage level required more insulation. So as the peak value of the AC is greater than DC for the same voltage level, AC needs more Insulation than DC.

(2) The AC needs more insulation and different insulation material which has high reluctance because the inductance effect can create interference to another device or equipment.

(3) The AC also needs different insulation material than DC because it may create a capacitance effect using the insulation as a dielectric medium.