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Don Rund

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I have severe frequency fluctuations when using a inverter controlled airconditioner.

The frequency is stable with any other load or lack of load.

The power supply is a 12 5kw diesel generator which is more than adequate.

Any resistive load smooths out the frequency perfectly.

Unstable frequency is only seen when airconditioner is on. The RPM is,stable The fluctuations are HUGE 3-112 Hz!

Can a capacitor remedy this?

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In that  type of air conditioner the input ac voltage is converted into dc via a power supply. The dc voltage is converted (inverted) into  variable frequency ac.

The frequency depends on the demand on the unit. A microcontroller  samples the ambient air temperature and adjusts  the speed of the compressor motor via the  frequency of the ac applied to the compressor motor.

Invert versus convert is interesting:

  • Inverter  - dc to ac
  • converter - ac to ac  (transformer, etc)
  • converter - dc to dc  (potentiometer, etc)
  • power supply - ac to dc
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Yes, that is true,  that is how it works.

But, the live frequency is steady until that inverter controlled compressor is on.

All other loads don't effect the frequency. 

The compressor has such a effect on the frequency,  that fans nearly stop one moment, and look like a airplane propeller the next!!!

All the while, the generators rpm is stable!

Any resistive load thats,applied, steady the frequency even when the compressor is running!

I can't have a hair dryer running 24/7 just to stabilize the frequency! 

Could a capacitor smooth the frequency? 

I can't have a hair dryer running 24/7 just to stabilize the frequency! 

Could a capacitor smooth the frequency? 

This is on a boat, why does the variable frequency affect the rest of the AC?

The compressor doesn't like it either, it eventually shuts down on error.

Again,  aNY load added smoothes out the frequency and then everything is fine.

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"Could a capacitor smooth the frequency? "

If one does not know what is  wrong with the system then one can not know what the affects of a capacitor would be.

  1. you have a 12 5kw diesel generator
  2. the generator outputs 120 or 240 volts at 50 or 60 hertz.
  3. the generator supplies the mains that has numerous outlets on the boat.
  4.  the generator output is stable until you turn on the ac unit.
  5. with the ac running the voltage  at the various outputs are no longer 50 or 60 hertz but varying in frequency

       6:     adding any load to an output corrects the problem.

 Is that correct?

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