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.

[SOLVED] Rectifying ac without transformer

Status
Not open for further replies.

Zak28

Advanced Member level 2
Joined
Aug 19, 2016
Messages
579
Helped
6
Reputation
12
Reaction score
6
Trophy points
18
Activity points
4,681
Is it bad to rectify ac mains power with high power diodes? Does it put harmonics onto the grid and make ac line dangerous for everything in the house or is it safe to do?
 

Hi,

Is it bad to rectify ac mains power with high power diodes?
Yes

Does it put harmonics onto the grid
yes, as soon as connect capacitors on the DC side

and make ac line dangerous for everything in the house
No

or is it safe to do?
It´s not "unsafe" for the grid
but the output of the rectifier is "unsafe" because it is high voltage and no isolation against earth

Klaus
 
  • Like
Reactions: Zak28

    Zak28

    Points: 2
    Helpful Answer Positive Rating
I greatly appriciate your answers, but I did not understand the isolation issue:

...the rectifier is "unsafe" because it is high voltage and no isolation against earth...

I see nothing dangerous about pulsating high voltage DC, its dangerous if its conducted thru the heart by touching it. Or is there some other danger to this isolation issue?
 

I presume the question is related to the project sketched in your previous thread **broken link removed**

1. The rectifier "puts harmonics onto the grid" with or without transformer. That's not particularly unsafe but possibly not conforming with regulations.

2. As said, electric circuits directly connected to the grid carry hazardous contact voltage. An isolated high voltage circuit can be however dangerous as well. An important difference is that if the isolated circuit has no other connections to ground or grounded external circuits, touching a single circuit node is not yet dangerous, the operation principle of a safety transformer.
 
  • Like
Reactions: Zak28

    Zak28

    Points: 2
    Helpful Answer Positive Rating
...2. As said, electric circuits directly connected to the grid carry hazardous contact voltage. An isolated high voltage circuit can be however dangerous as well...

To sum up your answer you basically said high voltage circuits are dangerous regardless of their configuration. Well they are dangerous and so are many low voltage circuits as well, its just skin resistance is normally too high for any significant current to flow.
 

I don't think it's appropriate to refer to commonplace statements in this regard. Safety regulations consider AC voltage above 42V and DC voltage above 60 V as hazardous contact voltage and require safe enclosures, to resume the most general rule. There are many detail specifications that must be considered for special conditions, e.g. wet environment.
 
  • Like
Reactions: Zak28

    Zak28

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top