A voltmeter must always be connected in parallel right? But when I have a transformer's secondary coil which is connected in series to it, then why is there a voltmeter reading? If i connect a battery in series with a voltmeter, the voltmeter reading will be the voltage of the battery right? So...
Ok, I have a primary and secondary coil. I set up a transformer between them. Each has 400 turns of coil(N). The primary coil produces a potential difference of 2.988 V. The secondary coil has a potential difference of 0.0551 V.
For the efficiency, I used the equation (Np*Vs)/(Ns*Vp) * 100%...
http://imgur.com/VsDrQ,dJ2iv#1
So according to the picture, I found the transformer voltage equation and current equation to be the following:
Precondition:
i1 is current in left loop
i2 is current in 2nd loop
Transformer Voltage Eq:
V1/N1 = 4i2/N2
Current Eq:
Ni(i1) =...
Along the same lines of connecting two transformer in series, Suppose the first transformer is a neon transformer with an output of 15KV, and the second transformer is a home-built built to handle 15KV on the input, and 15MV output. The problem remains, how do you couple a high impedance...
I have a uniquie project I am working on and was wondering if someone could tell me how it would be possible to control a mechanism using my current controller.
Right now I have a differential temperature controller that uses two sensor probes and turns on and off a 120V relay switch if the...
Well we can make a three-phase transformer using THREE single-phase transformers, but is it possible to make one, using only TWO single-phase transformers?
Homework Statement
Consider the motor arrangement shown, Assume ideal transformers and lossless transmission lines. The start capacitor shown in series with the motor is only used to start the motor, and is then shorted out of the circuit. The motor is loaded such that it delivers 5hp, and...
Homework Statement
[PLAIN]http://img192.imageshack.us/img192/8428/circuits.png
Homework Equations
\frac{V_L}{V_s} = \frac{nR_L}{n^2 R_s + R_L}
R_s = \frac{R_L}{n^2}
P = \frac{V_L^2}{R_L}
The Attempt at a Solution
How should I go about solving this problem? Do I have to...
hi guys, i was studying on transformers losses, i need help in some problems.
why open-circuit test show only excitation losses and not i2R losses..
thanks...
Hi, I'm new here, but to the point!I'm currently designing a system that I'm utilizing a series of 6 volt microchips to control. I have about 40 microchips at my disposal. that are C programmable , have a very good memory and all, multiple I/Os. And they have timers and oscillator systems and...
Homework Statement
In Figure 1, the transform is perfect (k = 1). Calculate the maximum power which can be transferred to the load ZL. Design a dipole which that power can be transferred to. Homework Equations
k = 1 --> n = sqrt(L1/L2).
Pmax = |V(rms)|/(4*Rg)
The result must be Pmax = 0.368 W...
Homework Statement
A 3-phase, 10KV, busbar of a power station is divided into three sections joined by two reactors as shown in Figure 1. Each section contains a synchronous generator and supplies a transmission line through a transformer. The parameters of genera-tors, reactors and...
1. when an alternating voltage is applied across the primary coil, an emf is induced in the secondary coil
2. when an alternating voltage is applied across the primary coil, an alternating current is induced in the secondary coilcan anyone tell me which one is true and why?
Thanks a lot.
Homework Statement
In our lab about transformers we have a question as follows:
Consider a loop in a uniform magnetic field. If the field is suddenly turned off, in which direction will the current flow in the wire?
Homework Equations
The Attempt at a Solution
My first thought...
Homework Statement
A simple transformer with negligable looses has a primary coil of 2000 turns and a secondary coil of 150 turns. if an AC current of 240Vrms is applied to the primary, calculate the secondary and primary currents if the secondary is connected across a resistor of 300 ohms...
I know step up transformers decrease power loss by the electrical cables, but I'm not quite sure how this works...
From what I understand, step up transformers increase voltage, hence decrease current, which means less power is dissipated by the cables since P=(I^2)R.
But then couldn't you...
Can anyone give me a source where i ca completely ready about the electrical phenomenon in transformers like the terminology, single phase , 3 phase transformers and then torque and mef production ??
a textbook was prescribed to us in college but it really contains a lot of mistakes and makes...
I don't even know where to start! anyone got any ideas?
A transformer having a 2:1 turns ratio is considered to have a primary resistance and reactance of 1ohm and 2ohm respectively, and a secondary resistance and inductance of 1ohm and 6.37mH respectively. Magnetising current for this...
Homework Statement
Hey PF!
I had a problem that was bugging my mind. We know that in any circuit, the total resistance has to equal the total voltage divided by the total current, right? That is, R=V/I. And we also know that when you have a step up or step down transformer, power is conserved...
i never heard of such a thing but what could be the circuit analysis to this?
http://i.imgur.com/Zd6qn.jpg
what is V1 and V2?
what could make V1 and V2 not equal?
I am confused from a couple of diagrams I have about how to correctly wire 3 small transformers to form a delta wye connection. The transformers are labeled as
Primary H1 H2, H1 H2, H1 H2
Secondary X2 X1, X2 X1, X2 X1
My question is in all the diagrams I have the Delta connections...
Hi,
so I have been having sleepless nights about this concept.
From what I understand, say a typical power generating plant that produces 2000MW of energy, for example, will want to transmit as much of 2000 MW of power to the grid as possible and they do so by stepping up the voltages to...
Before a few days ago I always thought that when transformers decrease the voltage, the transformers increase the current. Then on another thread at Physics Forums, people have told me that when transformers decrease voltage, they don't increase the current. The PFers told me that the...
Hey guys, i cannot make heads or tails of the concept of "Transformer Polarity". Tried looking for the material on the web but still couldn't get it. So, please help me out with dot polarity!
Thanks
my professor gave us a 30v power supply using a center tapped transformer and wanted us to simulate it in pspice.
He told us to use the k linear function to connect inductors together.
The problem is that I got it to work, but when I simulate it I get something that I don't know that I am...
Well the next step in my coilgun is a decent power source i every camera circuit that i use is burned up so i thought that i use a transformer well a audio transformer as the voltage multiplier but i can't seem to wire it right it actually doesn't charge the capacitors so i was wondering if it...
This is a problem I stumbled upon after noticing a pattern in the lab- the measured current was never quite what you'd expect from the turns ratio of either transformer alone, but somewhere in the middle.
I used 50:5 nominal turn toroidal CTs with 15 turns in one CT primary and 5 turns in...
Hi there
I am presently studying for my electrical machines exam and i have a few examples to tackle.
A 50hz, 3 phase, core-type transformer is connected star-delta and has a line voltage ratio of 11000/400V. The cross-section of the core is square with a circumscribing circle of 0.6m...
Homework Statement
You need a transformer to reduce a voltage of 150 V in the primary circuit to 25 V in the secondary circuit. The primary circuit has 130 windings and the secondary circuit is completed through a 55 ? resistor. (a) How many windings should the secondary circuit contain? (b)...
Based on Maxwell's equations, a physicist suggests that there should be a way to have a transformer to step-up or step-down gravity:
http://www.technologyreview.com/blog/arxiv/25407/
What could such a gravitomagnetic transformer look like in nature?
So I've been confused about transformers lately. In searching for some information regarding the basic transformer, I came across this: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/transf.html#c1. While this page was informative, I am still left confused in regards to one point in...
Hi physics gurus
Homework Statement
What should the primary voltage be changed to in order to produce a secondary current of 10 A, given that the V / I ratios for the coils do not change?
Current ratios that I have calculated so far are as follows:
Np (200) Vp (1200) Is (15)...
1. Lets say I put a resistor with a value 1 ohm on the secondary side..
what happens?
[PLAIN]http://img256.imageshack.us/img256/9639/67417248.jpg The thing is, in theory I just calculate the Z value and find out what it is. BUT, why does it have to be that. Practically, what would happen if I...
Homework Statement
Three single phase transformers rated 100kVA, 13.2kV/2.4KV are connected in wye-delta on a 3-phase, 18kV line.
I need to find the maximum load that can be connected to the transformer bank and the outgoing line voltage.
Homework Equations
The Attempt at a...
My question is if you connect multiple transformers together with the secondaries in parallel, how do you calculate the sum current from the transformers. Is the current calculated by dividing the voltage on the secondary winding by the impedance of the secondary windings.
Or is it based on the...
I need to know the purpose of using different numbers of coil turns for the primary and secondary coils on a transformer, provided the turns ratio remains constant.
Put into context, what is the difference between a transformer with 10 turns on the primary, 20 turns on the secondary and a...
Hi,
I've been a bit confused with how the equation Vp/Vs = Np/Ns came about. From reading a physics textbook, I understand that the voltages came from the emfs ε (primary) and ε (secondary). The primary voltage through the primary coils causes a change in magnetic flux which induces an emf...
hi guys,
I want to know if it is always possible to link two transformers in series with different rated voltage. And if there is any concern about the polarity.
If it is not possible in which conditions it can be done?
Homework Statement
A current transformer has a primary winding of two turns and a secondary winding of 100 turns.
The secondary winding is connected to a ammeter with a resistance of 0.25 ohms.
the resistance of the secondary of the current transformer is 0.75 ohms.
The value of current in...
This is a question written in my book, i tried to solve it but didnt work with me.
Homework Statement
A power station delivers a power of 150kW to small town at 15km from the station. Energy is transmitted by means of a transmission line of total resistance of 0.6 _()_ (ohm). The power...
Homework Statement
An electric power plant generates electricity @ 22 kV
and 100 A. The voltage is stepped up to 240 kV before
being transmitted to a city 15 km away over a copper
wire that has a radius of 2 mm. Energy is lost in heating
the wire during transmission. If the transformer...
Why transformers hum?
I have heard two versions. Oxygen has unpaired electrons and it reacts to changing magnetic field. Material that transformer is made of vibrates in changing magnetic field.
Both explanations tell that something vibrates in a magnetic field, but what it is?
Apparently my modern electronic home electric meter uses a 'current transformer' to measure the current in order to calculate the wattage I am using.
My question: is the flux generated in the current transformer also proportional to the reactive part of the current as well as the in-phase...
In poor countries, the domestic electricity supply is inconsistent, and even though the country's standard voltage may be 220V, it is not unusual for the voltage to go quite a bit below this level, say around 150V.
So normally, households buy step-up transformers, so that they can increase...
Homework Statement
http://img265.imageshack.us/img265/8616/43354308.png
I have an exam coming up in a few days and I am doing some revision questions from some past exams and this is one I have attempted but I have no solutions to check my answers.
The Attempt at a Solution
using Vs = 12cos(...