# Charging cap with three phase

Discussion in 'General Electronics Discussion' started by Andrew Borg, Nov 13, 2019.

1. ### Andrew Borg

42
4
Aug 10, 2014
Sir I need to charge a capacitor with three phase generator. Did three diode bridge but not charging. Any clue pls?
Thks

2. ### duke37

5,364
769
Jan 9, 2011
Three diodes will need a four wire drive.
Six diodes in a bridge can operate without the common wire.

3. ### Andrew Borg

42
4
Aug 10, 2014
Hi duke37 you're right I meant six diodes regarding the bridge. I connected the three wires coming out of the generator to the middle of those six diodes but cap not charging.

47
15
Nov 20, 2018

1,599
632
Nov 8, 2019
6. ### duke37

5,364
769
Jan 9, 2011
Disconnect the bridge,
Measure the resistance between the alternator outputs. Three readings.
Measure the output voltage between the three alternator outputs when running. Three readings.

Measure the resistance or voltage drop of each diode at both polarity. Twelve readings.
If one reading is different to the rest, disconnrct one end and measure it on its own.
Measure voltage drop across the bridge at each polarity. Two readings.

7. ### Andrew Borg

42
4
Aug 10, 2014
Thanks guys for response here is my circuit but capacitor not charging don't know why is this??!!!

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8. ### bertusModerator

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632
Nov 8, 2019
Hello,

Can you measure the AC voltage between the phases?

Bertus

9. ### Andrew Borg

42
4
Aug 10, 2014
Depends how much generator is spinning but measured it all giving same voltage.

10. ### bertusModerator

1,599
632
Nov 8, 2019
Hello,

What capacitor do you use?
You have given no information on that.

Bertus

11. ### Andrew Borg

42
4
Aug 10, 2014
I am trying many but not one is holding charge. Is it maybe frequency problem??
Cannot understand why.

12. ### bertusModerator

1,599
632
Nov 8, 2019
Hello,

You say you have tried several capacitors.
What where the values of them?
Is there a load accross the capacitor?
Depending on the load, the capacitor will be drained sooner or later.

Bertus

13. ### duke37

5,364
769
Jan 9, 2011
Unless youu have a very sophisticated meter, it will discharge the capacitor. To get a significant discharge time you will need a large electrolytic capacitor and a meter with 10M input resistance.

bertus likes this.
14. ### Andrew Borg

42
4
Aug 10, 2014
No I tried with no load

I used it on other capacitor without problem.