SCR stuff - Electronic Circuits Projects Diagrams Free

conchord · 30th May 2008, 01:23 PM

Sup peeps,
I'm having trouble finding a formula for a question.

I need to find the power delivered to the load if phase control is used when the trigger angle is 60 degrees

Leftyretro · 30th May 2008, 04:01 PM

Quote:

Originally Posted by conchord

Sup peeps,
I'm having trouble finding a formula for a question.

I need to find the power delivered to the load if phase control is used when the trigger angle is 60 degrees

Well considering that a single SCR can only work on 180 degrees of a sinewave (triacs can work on full 360 degrees) I would say (180-60) / 360 = 33.33% power delivered.

Lefty

on1aag · 31st May 2008, 02:56 AM

Hi Conchord,

First you calculate the power from 0 to pi, that's 50 %.
Then you calculate the power from 0 to pi/3 and subtract
this value from the previous one. You will find 46,875 %.
But the SCR only conducts from 0 to pi therefore the
power supplied to the load is 46,875 %.

on1aag.

crutschow · 2nd June 2008, 05:23 PM

Since power is function of the voltage squared, the power delivered to the load is not a linear function of phase angle. (See Dimmer Phase Angle Test for a simulated example at selected phase angles.)

To determine the power requires the calculation of the rms value of the truncated sine wave, which is not a simple function.

It also depends upon whether the load is constant resistive or incandescent lamp whose resistance varies with brightness..

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Latest
Some interesting stuff	irisd	Alternative Energy	0	10th January 2008 01:33 AM
obtaining stuff	spuffock	Micro Controllers	9	23rd July 2007 06:20 PM
Rfid stuff	nuttaphong191	Electronic Projects Design/Ideas/Reviews	2	18th June 2007 06:20 PM
HV stuff	Overclocked	General Electronics Chat	6	12th October 2005 05:24 AM
IR stuff	Josh	General Electronics Chat	4	4th May 2004 12:42 AM

30th May 2008, 01:23 PM	(permalink)
conchord	SCR stuff Sup peeps, I'm having trouble finding a formula for a question. I need to find the power delivered to the load if phase control is used when the trigger angle is 60 degrees

31st May 2008, 02:56 AM	(permalink)
on1aag	Hi Conchord, First you calculate the power from 0 to pi, that's 50 %. Then you calculate the power from 0 to pi/3 and subtract this value from the previous one. You will find 46,875 %. But the SCR only conducts from 0 to pi therefore the power supplied to the load is 46,875 %. on1aag.

2nd June 2008, 05:23 PM	(permalink)
crutschow	Since power is function of the voltage squared, the power delivered to the load is not a linear function of phase angle. (See Dimmer Phase Angle Test for a simulated example at selected phase angles.) To determine the power requires the calculation of the rms value of the truncated sine wave, which is not a simple function. It also depends upon whether the load is constant resistive or incandescent lamp whose resistance varies with brightness..