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# Imported Low Frequency Transient Susceptibility Power Lines calculation

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#### Winsu

##### Full Member level 3
Hi All,

Happy new year all.

I want to calculate the amount of energy MOV or TVS needs to dissipate when they are going to experience a transient.

There a low transient test for the Def Stan 59-411 that specifies the following:

That basically means that if the EUT has a nominal input of for example 24V, the test will inject 600 V+/- 10% at a frequency of 15.9Khz.

I need to calculate how long takes half period of time of 15.9khz to calculate the energy dissipated ( 16khz to make it easier).

T= 1/2* f -> 31.25us.

Once I have the shape of the curve ( lets assume it is sinusoidal), the peak voltage and the how long take half period of the signal, how can I calculate the energy that needs to be dissipated to protect the product?

Can I assume the RMS value of the 600V peak which is 424V ?. Then if the max current supply by the source is 600V/10ohm = 60A

Can I say that the device has to dissipate P = V* I * T = 424V * 60A * 31.25us = 0.795w?

If my calculations are correct, how can I compare it with the MOV chosen to know if it would absorb the energy or no?

Below is the table of the MOV chosen. The second last column indicates that wattage maximum in two seconds....., how I do compare my results to verify that MOV would resist the energy.

I may mixing concepts or missing some relevant information, if you could please give a hand that would be very helpful, thanks

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