Showing posts with label power switches. Show all posts
Showing posts with label power switches. Show all posts

Tuesday, January 29, 2013

Ideal switch

What is Ideal Switch?
Ideal switch is a switch that not consume or dissipate any power from its sources. The ideal switch is represent in Figure 1.


Figure 1.  Ideal switch


When switch is closed, the current flow trough the switch is equal to the current absorb by the load. But, the voltage across the switch terminal is equal to zero. From here, we can write:



Isw (closed) = Iload
Vsw(closed) = 0

So that, the power absorb by the switch while its closed:
Pclosed = Vsw(closed) . Isw (closed) = 0


Then what happen if the switch is open? While switch is open, there is no current flow to the load, so the voltage across the switch is equal to the voltage source. Thus, we can write:


Isw (open) = 0
Vsw(open) = Vsource

So that, the power absorb by the switch while its closed:
Popen = Vsw(open) . Isw (open) = 0

From all equations above, we get:
Plosses = Pclosed + Popen = 0 + 0 = 0

So, as mention above, the ideal switches don't have a power losses.