Which comes first?

[Besoeker]

you can't have v without I given there is a load

Not correct, sir.
The I is a RESULT of the applied voltage. The voltage is instantaneous. If you look at the Steinmetz equivalent you will see that the voltage is applied to X1 and R1. This means that I is initially zero and builds up as a transient. So, yes you do have voltage without current.

 

[Ingenieur]

Not correct, sir.
The I is a RESULT of the applied voltage. The voltage is instantaneous. If you look at the Steinmetz equivalent you will see that the voltage is applied to X1 and R1. This means that I is initially zero and builds up as a transient. So, yes you do have voltage without current.

incorrect
you can have v without I if v is impressed across z?
the load is R + Xlj, not purely reactive
so a component of I is instantaneous and limited by R
any time >0 you have I
voltage also has a rise time in the real world

 

[ActionDave]

I started a new thread where this discussion can continue.

 

[Besoeker]

incorrect
you can have v without I if v is impressed across z?
the load is R + Xlj, not purely reactive
so a component of I is instantaneous and limited by R
any time >0 you have I
voltage also has a rise time in the real world

The X1 and R1 are in series. You can't get current to flow instantly in an inductance. If it isn't in X1, it isn't in R1.
No more complicated than that.

 

[Besoeker]

I started a new thread where this discussion can continue.

What's wrong with continuing where it was? That is, after all, what it is what it pertains to.
OK.
The answer is obvious as I explained.

 

[augie47]

I started a new thread where this discussion can continue.

or not.. we will see if it turns into a p***ing contest

 

[Besoeker]

or not.. we will see if it turns into a p***ing contest

This is what I was trying to explain - the motor equivalent circuit.



You simply cannot get current to flow instantaneously in X₁
So voltage has to come first.
That's all.

 

[augie47]

:thumbsup:

 

[charlie b]

You simply cannot get current to flow instantaneously in X_1. So voltage has to come first. That's all.

I do believe you could present a similar case that starts with a current source and has and in-line capacitor. For that circuit, voltage cannot change instantaneously in the capacitor, so perhaps current comes first.

 

[Besoeker]

I do believe you could present a similar case that starts with a current source and has and in-line capacitor. For that circuit, voltage cannot change instantaneously in the capacitor, so perhaps current comes first.

Yes, but the thread was about SCIMs.

 

[gar]

180521-1654 EDT

When I first encountered this thread I had no idea what it was about.

If you have an inductor with zero initial stored energy (which also means zero initial current), then the instant just after voltage is applied to the inductor the current is still zero. This is a basic characteristic of an inductor.

.

 

[Besoeker]

180521-1654 EDT

When I first encountered this thread I had no idea what it was about.

If you have an inductor with zero initial stored energy (which also means zero initial current), then the instant just after voltage is applied to the inductor the current is still zero.

Succinctly put. Fundamental.
Thank you.

 

[Ingenieur]

it is an electro-magnetic wave
at any time >0 you have i


using the simplified ckt w/o xfmr reduce the ckt to
Zeq = Req + R2' / s + jXeq
is = V1 / Zeq

no v without i or vice versa

 

[Besoeker]

i
using the simplified ckt w/o xfmr reduce the ckt to
Zeq = Req + R2' / s + jXeq
is = V1 / Zeq

OK. But you seem to have omitted the magnetising bit.
No problem. I like simple. I just wouldn't get by with that.

Now, can we leave it at that please?

 

[Ingenieur]

OK. But you seem to have omitted the magnetising bit.
No problem. I like simple. I just wouldn't get by with that.

Now, can we leave it at that please?

it's in there, reactive components
the model with xfmr is the same but with rotor/field z reflected/combined

are you saying a motor can run without i ?
to run doesn't it need v and i (the product being power)
we discussing an induction motor, correct?

 

[Dennis Alwon]

This is like the old adage of what came first, the chicken or the egg. Can one exist without the other?

 

[Ingenieur]

This is like the old adage of what came first, the chicken or the egg. Can one exist without the other?

not in this inertial (and quantum) reference frame :lol:

 

[Besoeker]

it's in there, reactive components
the model with xfmr is the same but with rotor/field z reflected/combined

are you saying a motor can run without i ?
to run doesn't it need v and i (the product being power)
we discussing an induction motor, correct?

Shall we wait to see what the motor shop has to say?

 

[Besoeker]

This is like the old adage of what came first, the chicken or the egg. Can one exist without the other?

Very definitely.

 

[ggunn]

This is like the old adage of what came first, the chicken or the egg. Can one exist without the other?

Current can exist without voltage in a superconductor.