Input protection setting for DC-DC converter

[MD MUBDIUL HASAN]

Hi there,

This post is very easy one for you who knows better.

I am confused to set some values.
My DC-DC conveters input is 250-650VDC and output is 24V/5A. Its use for PV battery charger.
Take a look here,

I have few more query,

1. My boss want me to put some common ground ZNR” Transient/Surge Absorbers, in folloing manner, https://www.farnell.com/datasheets/2244565.pdf

2. Dont you think he needs it unnecessary for protection since there is 2 cap, 1 noise suppreser and rersistor are available.

3. He wants to add a fuse in pin 1 to R24, not sure why?

4 Can you imagine any idea to use R1-3? Those are 1 Mohms.

6. He wants to add a LED indecator for power output, for 5A current whats your idea?

 

[ronsimpson]

We do not understand the relationship between 250-650VDC and ground. Pin-1 could be at 650 while pin-4 is at 0V. OR Pin-1 = +300 and pin-4=-300.
I think you want to limit Pin1 to 4 at 700V and limit Pin1,4 to ground at 700. Three parts!
3. bad idea.
4. R1,2,3 are to discharge the capacitors. (C2)
6. Need to see more circuit.

 

[MD MUBDIUL HASAN]

We do not understand the relationship between 250-650VDC and ground. Pin-1 could be at 650 while pin-4 is at 0V. OR Pin-1 = +300 and pin-4=-300.
I think you want to limit Pin1 to 4 at 700V and limit Pin1,4 to ground at 700. Three parts!
3. bad idea.
4. R1,2,3 are to discharge the capacitors. (C2)
6. Need to see more circuit.

Yes, well noticed.
Let assume pin 2 and 3 are not connected
1. You did not talk about ZNR, does it meaningfull configuration.
2. Does L1 works with this datasheet? https://www.we-online.com/catalog/datasheet/74482210002.pdf.
3. Discharging resistor values are ok? Do you want me to see here, http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capdis.html
Take a look the image below, my minimum required ripple current is 11.04 A. The output filter is a simple LC filter consisting of L2 and C7 in the typical circuit. We need to design the filter to have a cutoff frequency much lower than the operating frequency, so that it will effectively reduce the switching noise observed at the output.

Where the LED indicator should add?

 

[ronsimpson]

Discharging resistor values are ok?

The laws I live under said, ' unplug power, open box (screwdriver) reach in and touch capacitor. By this time the voltage needs to be below 48V. ' It takes two pages of words to say that. LOL

reduce the switching noise observed at the output.

What frequencies do you see on the output? A big L and C will help at the switching frequency. But there might be 100mhz noise that will pass though the big L and the big C is not good at mhz. You might need a small LC right at the output connector. I cannot test from here.

You did not talk about ZNR, does it meaningfull configuration.

I would use 3 parts. Or one part. I do not see how 2 parts helps.