Hi,

If a 200kVar automatic type capacitor bank already installed but found the power factor still cannot be reached to 0.8.

Is it possible for us to install an additional power factor compensation system? Which type of system is better for this case? (i.e. Fixed type or Automatic type)

Thanks for your help.

John

Hello John

Yes you can certainly add more correction.
If you are currently using an automatic bank, then it may be posible to add more steps to that system. It depends on the number of steps that the controller is able to provide. If the controller is maxed out in steps, then you could consider increasing the size of the steps, or adding some static correction to some of the larger loads that run most of the time.
Adding a second automatic bank can cause problems if both are monitoring the same feeder. You can independantly correct two different feeders fed from the same point.

Best regards,

Hello Marke,

Thanks for your advise. The existing capacitor controller don't have spare relay output to connect extra capacitor module. So, we prefer to install additional static type capacitor module to compensate the base load of the system.

But do we neeed to have any considerations if the existing capacitor bank is detuned type? Because I hear it will change the orginal tuned frequency. Is it right?

John

Hello John

If you were to change the value of a capacitor within your existing controller, it would change the tuning. Addind capaciance outside of the unit is not an issue.

NB it is good practice to add detuning reactors to all capacitors used.

Best regards,

Hello Marke,

Thanks. That means we can install an additional "static type" capacitor with / without reactor also ok, which depends on the harmonic level of system. We also not must to install the additional capacitor with the same tuned frequency to the existing one.

Best Regards,

John

Hello John

I would recommend a detuning reactor is always used. You may be OK with harmonic currents today, but not tomorrow.
I see no problem with using the same "tuned frequency" as the existing one. Most people use 5% or 7% for all their plant.

Best regards,

Marke,
Thanks
John

Hi John there are automatic powerfactor controllers on the market which will accept non standard steps in your bank.
This will mean that you can add to your existing bank and just change your controller.
essentially they constantly monitor the load and record the amount of correction that occurs by bringing in each step.
Beware tho if your installtion has fast changing loads this can cause this type of controller to seek, or go into osscilation.
NHP in New Zealand do one of these type as standard, just be very carefull and do your homework first it may seem like an easy fix at first glance but can very easily turn nasty.
I would always suggest getting your sites power analised before doing anything with your correction banks.

Oh just another thing have you tested all your steps to make sure they are functioning correctly?