Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

230V Reverse voltage AC Protections

Status
Not open for further replies.
B

Bjtpower

Full Member level 5
Joined
Dec 24, 2015
Messages
297
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,298
Activity points
3,893
Hello Guys,

i am facing problem while designing the Transorb or the MOV here in my circuits.

Circuit is attached where user bimistakely apply the 230v to the Output side and it damages the 28V Circuit.

Now, in case my idea is to use the Fuse and MOV/Transil so that when voltage above the Transil voltage appears,Transil will take the max current so that the Fuse can be failed and i can save the 28v Circuitry.

So I can use the Fuse socket to replace the same.
Only fuse should have to blow.

Normal operation,it will pass 0.8A to the output side.
230V Problem.PNG

Let me know your inputs

Regards,
Marx
 

Hi,

Please read the MOV datasheet:
it says:
* I_MAX (8/20us) = 500A. Can you ensure this? If not then you may kill the MOV
* V_C (Clamp voltage) at 5A MOV_current (yes, 5A only!) = 77V. Can your circuit withstand this? If no then the circuit is still not protected.

My opinion:
For safe operation you need a current limiting device before the MOV. (You need to read the fuse datasheet according blow time vs applied current)
Then you may calculate the expectable clamp voltage.
In most cases you need a second stage for good protection.

Klaus
 

Can you pls Suggest..?

- - - Updated - - -

upto 35 volt it can withstand..?

I want to understand how you calculate the 77V..?

- - - Updated - - -

KlausST said:
Hi,

Please read the MOV datasheet:
it says:
* I_MAX (8/20us) = 500A. Can you ensure this? If not then you may kill the MOV

Klaus
Click to expand...
From the Datasheet it is Right.

KlausST said:
Hi,


* V_C (Clamp voltage) at 5A MOV_current (yes, 5A only!) = 77V. Can your circuit withstand this? If no then the circuit is still not protected.
Klaus
Click to expand...
How you calculated and can it be Lower to 35-40V..?

i want to blow the Fuse.?
 

Hi,

upto 35 volt it can withstand..?
Click to expand...
I don´t know.

I want to understand how you calculate the 77V..?
Click to expand...
Not calculated. It´s given in the datasheet. Read it.

can it be Lower to 35-40V..?
Click to expand...
It´s the characteristic of the used MOV. You can´t change the specification.
But you may choose another MOV. I doubt there is one that is for 28V operating_voltage and the same time for 35V clamp_voltage.

Klaus
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top