im doing project voltage regulation in portable generator, and im using EN3500 generator which contain meccalte spa S16W 90A ALTERNATOR. the thing is that i want to control the output voltage without any modification to the generator mechanically. this generator is self excited and brushless capacitive regulated single phase alternator. can i control the output voltage by controling the reactive power in this synchronous generator.

 

A circuit of generator would help. Is it simmilar to this one? FC is the rotor, C is the reg cap, SC is reactance winding.

 

the circuit is some what similar to that but it got some changes . i had attached the wiring diagram of the generator with this. so please give me a solution for this. im not possible to do any mechanical modification in this generator. the supervisor had asked me to look for electrical modification to improve the voltage regulation. im running short of time only one more month to do my practical work. so i kindly request you to give me direction to do this

 

Hi there anoopravi, The circuit is actually the same. I dont have an answer for you as i dont quite understand how these generators actualy regulate, so i started another thread asking if any one can give an explination on how it actualy works. I do understand how a slipring type generator works, but that is completely different.

 

did you get any details regarding this topic.if so please inform me fast

 

can i control the output voltage by controling the reactive power in this synchronous generator.

This looks like a question, but it would be more obvious if it ended in a question mark, and if the rest of the post was punctuated. If you can't take the time to write a proper post, few here are motivated to help.

We need more information. What output voltage are you talking about, the DC?

I have no idea what "controlling the reactive power" means. What variables CAN you control, and what can you NOT control or alter?

Generally (at least in automotive alternators), increasing the field current will increase alternator output. So the FC is under feedback control by system voltage.

 

how will i control the field current of above mentioned generator

 

I'm sure there are experts here that can better answer that, but isn't that the role of the voltage regulator, to send more current to the field windings when system voltage drops?

 

Un fortunately I think you have picked the wrong type of generator for this project, as they are crudely self regulating so long as the speed remains constant. A speed increase means an increase in output voltage & frequency. Ive done a bit of testing with the generator thismorning. The reactance winding across the capacitor has 153V ac & cap draws 1A @ 500Watt. @ 650Watt there is 158V AC & cap draws1.5A. @ 0Watt 125VAC & cap draws .5A. This is with a 10uf cap. No cap or O/C no voltage output but 6V ac on reactance winding. Change cap to18uf there is an increase in voltage across reactance winding to 175V ac & output voltage rises to 275V AC. Some how cap value affects the output voltage of the generator. Pity arent using a conventional slipring type generator. Waneh, these type of generator dont use a conventional regulator.

 

More information (schematic of internals) would be helpful.

How far out of regulation is the output voltage and frequency?

 

if iam connecting series capacitance at the output terminal will the voltage will be regulated. this generator is a capacitive regulated type .

 

if iam connecting a series capacitor at the output terminal, does the output voltage will be regulated. the main thing is that this generator is a capacitive regulated generated

 

if iam connecting a series capacitor at the output terminal, does the voltage can be regulated. the main thing is that this generator is a capacitive regulated generator.

 

NO this is a self regulating type generator & a poor example for what you are trying to do.

 

I would have thaught this type of generator would be a lot beter project. The regulator adjust a voltage feed to the rotor through sliprings to regulate the output voltage. It uses the 90V ac which is rectified to DC & this voltage is controled & fed to the rotor. In this particular Gen the voltages to the rotor are, 25V DC @ 120Watt load, 30V DC @ 500Watt, 46V DC @ 650Watt. The 25V AC is rectified to DC in the Regulator & is used for voltage sensing & driving the MOSFET which regulates the rotor voltage. Its up to you to figure out the actual circuit.

 

i didnt got it correctly. will you please make it much more clear

 

I dont quite know how mutch clearer you want it, without me actualy drawing up the actual circuit of the regulator.Ive given you all the relavent voltages. Some one else may be able to help as i will be off line for the next 4days.

 

how will the capacitor value been choosen in the auxiliary winding of the generator. my generator is self regulated and self excited one. now it already have a 14uf capacitor in the auxiliary winding. I want to increase the capacitance but i dont know how it can be found out. any one help me in this.

 

If you check GMC Brushless Generator in the search, you will find some CRO wave forms taken on this type of generator with different loads & different size capacitors.