Recent content by davidcowling

I need to find out how a certain pulse width modulation duty cycle is used in SMPS power supplies (specifically a boost converter). Also, how does the oscillation contribute to a voltage transformation? (step up) Any pointers to some articles are welcome

Homework Statement Propose a Second order Model in the continuous time domain Natural damping frequency of 0.6 Steady State gain of 2 units Write down the corresponding differential equation I have no idea where to begin with this, could someone help me with the process, then i will...

I don't have a reference for that, but iam 99% sure that is correct. Is it not right? I always thought that if you wanted to increase power output from a generator, give the turbine more steam. If you want to increase reactive power output from a generator, put more excitation current on the...

I am so lost. :(

I understand what that all means, but how does the amount of current on the rotor (field) influence the reactive power output?

you have completely confused me! im just curious as to how the excitation has an effect on reactive power output.

I know as a fact that excitation (amount of current on the generator rotor) determines the amount of reactive power output from the generator. But why? How does it turning the excitation up or down influence the reactive power output? Thanks.

Am i right in thinking that a synchronous machine used in a power station has to be spun past its synchronous frequency to generate electricity?

No its not. I am currently applying for a place on a graduate scheme and looking at some of the possible questions they will be asking. Thanks for your help

What sort of generator is used in a power station? (synchronous, asynchronous)... And what is the difference between. - Asynchronous Generator - Synchronous Generator - Alternator - Dynamo Thanks!

you mentioned in the first part of the question that the current is 36.8-J27.6 = is the 27.6 the angle? and what is the 46A magnitude? cheers

When finding the current in a 4+j3 balanced load star connected circuit. with 400V line voltage at 50Hz. Do you find the current by dividing the phase voltage approx. 230V by 4+j3 ohms? and if so. how do you divide normal numbers with complex numbers? your help is appreciated.

ok got it... now what's the difference between - asynchronous generator (induction) - synchronous generator and what is synchronous speed / frequency? do asynchrounous generators allow wind turbines to produce 50hz electricity even when the gearbox isn't spinning this fast? cheers

- Armature produces power - Commutators are the part of a rotating armature that brushes make contact with. They are for producing DC from a rotating armature or for making a motor work from DC. you said the armature produces the power, but is stationary. then you say that the...

What is the difference between, - Alternators - Generators - Dynamos - Rotors - Stators - Armature - Field - Commutators - Brushes. My mind is filling up with terms and I am struggling to make sense and define the difference between each! your help is appreciated.