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Should I earth my supply ground?

S

siliconmike

Jan 1, 1970
0
Should I earth the ground of an SMPS that I'm building? What are the
pros and cons?

It will be housed in a plastic case.
Hopefully I'll be able to coat the inside of the plastic case with
metal for EMI prevention.

Or in general, why are grounds earthed?

Mike
 
L

Luhan

Jan 1, 1970
0
siliconmike said:
Should I earth the ground of an SMPS that I'm building? What are the
pros and cons?

It will be housed in a plastic case.
Hopefully I'll be able to coat the inside of the plastic case with
metal for EMI prevention.

Or in general, why are grounds earthed?

If by earth ground you mean the 3 prong on the ac power plug, then the
answer is yes.

If you mean an 8 foot copper rod driven into the flowerbed outside your
window, no, not unless you are running a shortwave transmitter.

Luhan (formerly K9WUZ)
 
P

Pooh Bear

Jan 1, 1970
0
siliconmike said:
Should I earth the ground of an SMPS that I'm building? What are the
pros and cons?

It will be housed in a plastic case.
Hopefully I'll be able to coat the inside of the plastic case with
metal for EMI prevention.

Or in general, why are grounds earthed?

See 'protective grounding / earthing'.

Graham
 
S

siliconmike

Jan 1, 1970
0
Luhan said:
If by earth ground you mean the 3 prong on the ac power plug, then the
answer is yes.

And what is the reason...? in short..
 
S

Stanislaw Flatto

Jan 1, 1970
0
siliconmike said:
Or in general, why are grounds earthed?

Mike

Theory: "Ground" is an infinite capacitor without any resistance or
inductance and can accept currents of any size and frequency without
building a voltage difference.
So supposedly it is a reference point and any grounded equipment,
working OR faulty does NOT built voltages that can be fatal to people.
(Have you ever got a static shock from body of car, then you know what I
mean)
In practice every part of equipment is connected (sometimes) to ground
with a wire and the electrical properties of the connection will
determine the quality of "grounding".

HTH "in general"

Stanislaw
Slack user from Ulladulla
 
M

Mochuelo

Jan 1, 1970
0
Theory: "Ground" is an infinite capacitor without any resistance or

You meant "conductor" instead of "infinite capacitor."
inductance and can accept currents of any size and frequency without
building a voltage difference.

IOW, ground is ideally an equipotential volume, as large as needed by
our system, to be used as a potential reference.


Best,
 
L

Luhan

Jan 1, 1970
0
siliconmike said:
And what is the reason...? in short..

This tends to prevent slight voltage potential differences between
electrical devices. It is also a safety condideration: if something
shorts internally to the frame, the frame being grounded will blow a
fuse instead of frying someone who touches it.

Luhan
 
P

Pooh Bear

Jan 1, 1970
0
siliconmike said:
And what is the reason...? in short..

To comply with safety standards is the legal reason.

Graham
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
Stanislaw said:
Theory: "Ground" is an infinite capacitor without any resistance or
inductance and can accept currents of any size and frequency without
building a voltage difference.
So supposedly it is a reference point and any grounded equipment,
working OR faulty does NOT built voltages that can be fatal to people.
(Have you ever got a static shock from body of car, then you know what I
mean)
In practice every part of equipment is connected (sometimes) to ground
with a wire and the electrical properties of the connection will
determine the quality of "grounding".

In practice, most grounding electrodes are pretty crappy. Most have
pretty high impedances relative to the fault currents they will carry in
the event of a short to true ground.

What is very important is the bonding between the premises ground bus
and other conductive parts of the structure (like water pipes). I don't
care so much if the potential of everything in my house jumps 50 or 100
volts relative to some ideal ground. I just want all the objects in my
house to remain at the same potential WRT each other.
 
G

Genome

Jan 1, 1970
0
siliconmike said:
Should I earth the ground of an SMPS that I'm building? What are the
pros and cons?

It will be housed in a plastic case.
Hopefully I'll be able to coat the inside of the plastic case with
metal for EMI prevention.

Or in general, why are grounds earthed?

Mike

MEHNEER MONG MONG MING MENEER NUHHH NUHHH BURGH NAHHH NEEERRRRR
 
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