Grounding and Switching Power Supplies

[sr1200]

Just curious as to why we dont need to "ground" a switching supply. I've recently seen a bunch of newer devices come out that have switching supplies (some of them delivering HIGH voltage) but have no ground pin. Just the standard 2 pin polarized plug. (US). Is there an advantage to this? Is it just a cost savings thing? Is it just NOT needed?

 

[Matador]

It's called "double insulated".

https://c03.apogee.net/mvc/home/hes/land/el?utilityname=wppi&spc=foe&id=17575
https://oshatraining.com/wp-content...ectrical_Safety__–_Double_Insulated_Tools.pdf

 

[sr1200]

Double insulated microphones... hmmm.

 

[Newmarket]

Double insulated microphones... hmmm.

Transducers don't come into it. And there's nothing here specific to switching supplies. Perfectly possible to have a linear supply that is not "grounded". If you mean connection to the planet Earth.

 

[ccaudle]

I've recently seen a bunch of newer devices come out that have switching supplies (some of them delivering HIGH voltage) but have no ground pin

Most consumer devices have been two pin only for many decades. High output voltage does not have any bearing on whether the equipment can be two pin input or not, but I believe there is a power limit for double insulated designs. I do not know if the power limit is by regulation, or only because it becomes unreasonably difficult to meet the class II requirements at higher power.

 

[user 37518]

Double insulated microphones... hmmm.

Not a bad idea:




And something to light up the mood:

 

[sr1200]

Omg to the first one, his body seized hardcore.

Lol to the second.


But seriously, maybe im missing something, but i just dont see it as a good idea for a mic. Is it really not necessary?

 

[Matt Syson]

It takes a considerable amount of filtering (inductor and capacitors) to prevent a switchmode supply from 'transmitting' high frequency switching noise considering anything above say 30KHz is considered to be radio frequency. Using a pair of capacitors and creating a 'mid point' potential which the bulk of the metalwork in a small 2 pin (ungrounded) unit (phone charger etc) and enclosing all the electronics inside the case which may have conductive layer sprayed onto the inside of a plastics casing may be enough to prevent 'transmission' and it is the cheap devices that may not have adequate filtering that cause problems. All decent sizes switchers have a metal casing that must be grounded and still it is up to the user to ensure that module is in a suitable enclosure for safety and emissions purposes. A switcher 'module' has to be considered to be a 'component' (like a transistor or Integrated circuit. A good start but NOT a finished workable product until properly enclosed (and wired obviously).

 

[JohnRoberts]

Not a bad idea:




And something to light up the mood:

if I was standing in water I would insist on using a wireless microphone.

JR

PS: I had a rusted out hot water heater shock me in my shower.

 

[user 37518]

considering anything above say 30KHz is considered to be radio frequency.

I know many RF guys who would consider that DC. But yes, I get your point.

I work in RF/Microwave, but since I also like audio I am referred to as the "low-frequency dude" by my peers.