Today is...
Wednesday, July 1, 2015
Welcome to Control.com, the global online
community of automation professionals.
Featured Video...
Featured Video
A quick introduction to EtherCAT for motion control and I/O...
Our Advertisers
Help keep our servers running...
Patronize our advertisers!
Visit our Post Archive
what is floating earth system?
What is floating earth system? Why it is being used for the MarkIV and MarkV system?

What is floating earth system? Why it is being used for the MarkIV and MarkV system? If we use normal earth and voltage system what can occure.

By markvguy on 6 May, 2007 - 5:36 pm
1 out of 1 members thought this post was helpful...

Mk IV-, Mk V-, and Mk VI Speedtronic turbine control systems DO NOT use a "floating earth" system--they use a floating nomimanl 125 VDC battery/power supply system.

They use this for two reasons: First, it's possible to detect a ground on either "leg" (positive or negative) of the power supply as it's used in the system. Second, if one leg were grounded, such as is done on a car (where, typically the negative leg of the battery is grounded), if a ground develops on the positive leg it's like a dead short across the battery! And, grounds on the negative leg can't be detected.

markvguy

1 out of 1 members thought this post was helpful...

Yes I agree with the given fact above. but Floating Electrical earthing system is were there is 3 phase system. when there is one earth fault then you have to sort it out or then if second earth fault arise of another phase on same ground system will cause short circuit. but they should be direct short to ground and not via resistance. These system is not using body earth to the chassis but one type of proper ground. Now a days they use Earthing Transformer.

Vedant.R.Sawant.(Mulund East)
Electrical Engineer,
India & Brasil.

i am just repeating the original question, "what is floating earth system?" i don't think its been answered. and why its considered better than the original earth?

Don't know about the MARK systems specifically, but in general any time the word "floating" is used with respect to an electrical system, it means the system (or an electrically-isolated portion of a system) has no external voltage or current reference (i.e. seemingly infinite impedance to external parts).

Simplest explanation: the expression "floating (something)" is equivalent to "electrically-isolated from (something)".

Take any battery system as an example. You have voltage across the terminals, but there is no voltage from either terminal to non-connected parts. This battery system is "floating". Once an electrical connection is made, either by intent or fault, between a conductive part and either battery terminal, there will be voltage between that part and the other battery terminal.

Considering the preceding, you could also have a chassis-grounded system where the chassis is intentionally isolated from earth-bonded conductive parts... so you will have a chassis-grounded system but not an earth-grounded system.

FWIW, "floating earth system" is a misnomer, but some will take it as intended. Earth cannot be "floated" unless you happen to have god-like powers and want to create major disasters for earth-bound entities. It is the electrical system which is "floated", and in some cases the so-called grounding system thereof... but not Earth itself :)

> i am just repeating the original question, "what is
> floating earth system?" i don't think its been answered. and
> why its considered better than the original earth?