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Hello Jim,
Your article is absolutely clear. Can you respond to ud on e mail
if you can help us by personal visit to Maddur via bangalore India to solve the issue …our Elec Board,
CATERPILLAT (GENSET Mfg) and EMERSON (UPS Mfg) are unable to find a solution.
Pl. advise by e-mail ASAP. regards : KLENE PAKS
in 50hp VFD i got THD i is 67%..
please tell me the allowable limit of that.same way allowable limit of THD i for UPS system
I couldn’t refrain from commenting. Perfectly written!
Hi Jim,
I have something different to ask you about please. I recently discovered that it is possible to take 3 phases 400 Volts AC 50 hz and with the help of a choke and a capacitor, make it a 3 phase balanced supply to a 2 phase 400 Volts induction furnace. But I know very little about it and wish to understand this better. Can you help? We have 12 furnaces on 2 phases and the power is very unbalanced all the time. The furnaces are being switched by thyristors at present from a PID configured Eurotherm 3204 temperature controller putting out 4 to 20mA to a phase angle card driving a back to back thyristor pack in one leg of the 2 phase supply.
I also wish to understand how switching it with IGBT drivers will work and if it is better, since I have been advised to change the thyristor control to IGBT. Can you help me with advice here also please?
Cobus
I’m very happy to find this web site. I wanted to thank you for your time just for this wonderful read!!
I definitely loved every little bit of it and i also have you
saved as a favorite to see new information in your web site.
Please supply contact details for South Africa.
nathan.potgieter@schneider-electric.com
Nathan is the Product Manager for Power Quality. He will be able to put you in contact.
Regards,
hey jim .. I am confused about the selection of harmonic filter.. If i want to put a harmonic filter in 500kvar PFI plant what should be the rating of harmonic filter
Hi, Manzoor,
There are two main methods to select an active harmonic filter.
1) Know the plant operating details: Could be from continuous monitoring (already have appropriate metering installed); could be from performing a harmonic study; or could be from performing a simulation. All provide details about V (phases and neutrals, if appropriate), I, KW, KVAR, KVA, PF, THDi, and THDv. From this 9information some good sizing can be attained.
2) If planning/designing a facility, simple calculators provided by the active harmonic filter (AHF) manufacturers allow entry of load sizes and types and utility/generator source information. This is more conservative than point 1 above. But it permits one to know what will meet the harmonic standards and protect the eventual users.
You need to define the starting point and decide what the standards of compliance to be applied.
Regards, Jim
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