phase sequence relays

[electrics]

also i wonder if the maximum phase shift of a voltage phase can be 180 degree?? can we talk about a phase shift of 270 degree?? (ı guess non)
Also i am beginning to get what u meant, u mean
i have a current lagging 60 degree to the source voltage
now i have a resistance on this circuit inherently and this resistance will create a 60 degree shift
now i set up a second circuit with this resistance as source and make the things done above again and hellaluja i have a 120 degree phasehift???
i guess i found thank u if i am not wrong, if so pls tell me why not...

 

[mivey]

I examined the link u gave me but still couldnt get how can it be achieved, it seems to be explaining how a phase shift less than 90 degree can be achieved. you say "Stage two of those and you have 120 degrees" what does stage two mean?
if u dont want to give answer i feel respect for u still since i always ask what i know
in fact i dont know how phase can be shifted with RLC circuits..

Staging was slang for cascading the RC combinations.

 

[mivey]

can u show me how a 0 degree phasor can be shifted to - or + 120 degree phasor using a simple circuit?

Take a source V<0? (using the "<" symbol to denote angle). Pick one lead as the reference (call this point "0"). Take the other lead to a 1uF capacitor (C1). From the other side of the capacitor (call this point "1"), connect a 1500Ω resistor (R1) to reference.

Also from point "1", connect another 1uF capacitor (C2). From the other side of this second capacitor (call this point "2"), connect a 1500Ω resistor (R2) to reference.

The voltage at 1 will be about 60? ahead of the source. The voltage at 2 will be about 120? ahead of the source. But let's do the math:

The final stage has an impedance of:
Z2 = R2 + jXC2 = R2 + j(-1/(2*Pi*f*C2) = 1500 + j(-1/(2*Pi*60*1E-6uF) = 1500 -j2652.58 = 3047<-60.51?

I2 = V1<? / |Z2|<-60.51? = V1/|Z2|<60.51?

Z2 is parallel with R1 so the impedance seen by the source is:
Z = jXC1 + (R1 || Z2) = -j2652.58 + (1079.08 - j372.18) = 3211.48<-70.366?

Letting V0=1<0?:

V1 = 0.3554<51.337? (the voltage across R1)
I0 = (3.11E-4)<70.366? (the source current)
I1 = V1/R1 = 2.3695E-4<51.337? (the current through R1)
I2 = I0 - I2 = 1.166E-4<111.849? (the current though R2)
V2 = I2 * R2 = 0.175<111.849? (the voltage across R2)

So we have 51.337? in the first stage and 111.849? in the second stage. Some tweaks to the component values can get you 120? at R2.

I bread-boarded this circuit to see how close it might be and got 52? and 112?

 

[mivey]

also i wonder if the maximum phase shift of a voltage phase can be 180 degree?? can we talk about a phase shift of 270 degree?? (ı guess non)

There is no limit to the amount of shift, although in steady-state conditions it becomes a mute point after so many degrees. Eventually, you could look at the graph and say that the current leads the voltage by 270? or that the voltage lags the current by 90?. It some cases it may not physically matter, even though only one way might be techically correct.

That may not be the case with transient conditions. The term phase shift is also used to indicate time shifts so you have to be clear on what you are talking about.

Also i am beginning to get what u meant, u mean
i have a current lagging 60 degree to the source voltage
now i have a resistance on this circuit inherently and this resistance will create a 60 degree shift
now i set up a second circuit with this resistance as source and make the things done above again and hellaluja i have a 120 degree phasehift???
i guess i found thank u if i am not wrong, if so pls tell me why not...

You got it. Actual phase shifters are a little more complex and may be digital or have ciruits with transistors, op-amps, etc.

 

[electrics]

okey mivey i reaaaaaalllllllllllllly appreciate u, it is very kind of u to explain everything witj jeweller meticulousness, i got also that it is up to 369 degree that phase difference can be maximum, i just got confused and it is okey now, i thank u sincerely u are a nice and kind friend of mine...