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.

Mains transient lasting 2 seconds?

cupoftea

Advanced Member level 5
Joined
Jun 13, 2021
Messages
1,681
Helped
42
Reputation
84
Reaction score
87
Trophy points
48
Activity points
8,853
Hi,
We have been asked to bring up a 500W PFC’d full bridge SMPS for a customer.
115VAC, VOUT=28, PFC=200KHZ, Fullbridge=250kHz, PFC chip = UCC3818.
Its hard to get past their project managers and to speak to their actual engineers.
Their spec says "VAC input = 105-124VAC".
However, it also says that the VAC input may go up to 172VAC for 2 seconds, and the PSU should be able to “withstand” this. So, the spec says “Input transient withstand = 172VAC”.
Do you know what on earth could make the VAC input do this?.....would it be a smooth rise up to 172VAC, or a brick wall rise to it?
I don’t see the point of having the PFC Vout set to 275Vdc (which they have), when the peak of 124VAC is just 175V…..I believe we should change PFC vout to 235Vdc. Would you agree?
(We can bypass the PFC sense resistor and PFC inductor with diodes for any surge currents)
 

Easy peasy

Advanced Member level 5
Joined
Aug 15, 2015
Messages
4,244
Helped
1,336
Reputation
2,672
Reaction score
1,713
Trophy points
1,393
Location
Melbourne
Activity points
23,715
A PFC DC rail of 200V is reasonable, as is bypass diodes to handle surges, but the caps should be rated to at least 250VDC ( + surge if you can buy them ) to avoid catastrophy.
 

LaTeX Commands Quick-Menu:

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top