RE: Grounding of negative lead on SSTCs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mccauley, Daniel H" <daniel.h.mccauley-at-lmco-dot-com> 


Connecting the DC negative to ground is not only done for safety, but to
reference the controlc circuitry to ground.

The reason power supplies are not ground referenced is because they are
typically built as ISOLATED supplies which allow
the use to run as ISOLATED if required.  For example, if I wanted to use
a DC power supply to bias my gate drive circuit
on the high side, I could use an isolated supply output to do this
(provided the supply has enough isolation).

Typically, however, you want to have your negative output tied to earth
ground as a reference.

Dan



 > Hi all,
 >
 > I noticed on Dan's 15 kW SSTC schematics that the DC negative is
 > directly connected to the mains ground. I am used to see that
 > done (and
 > do that) through a capacitor. I guess there is a safety issue
 > here but I
 > can't recall the reason. Usually bench DC power supplies give the
 > possibily to externally ground the negative to the mains ground (and
 > chassis): it isn't readily wired.
 >
 > Can anybody recall/explain the reason why to do it in one or another
 > way?
 >
 > Regards
 >
 >
 >