Can anybody tell me if capacitor bank can be controlled by means of PLC without a power meter?

 

Responding to Anonymous' query....
What are you trying to "Control?"

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected]) {[email protected]}

 

Dear Anonymous,

I think an easy, cheap, safe and reliable method would be to put specialized relays with the requisite number of steps to control the bank. With a PLC you will have to sense the difference in phase angle between current and voltage. Could be done with zero crossing and counting the
interval, but it would take a really good PLC scan time and deft programming to preclude problems from PLC scan times.

If you are in India then Alstom makes a good relay for the purpose.

Bye,

Tomy

 

Perhaps I misunderstand the question, but it seems to me that you will need something to monitor power in order properly control a capacitor bank. It is possible to use a PLC to control a capacitor bank if the PLC is able to precisely measure the phase angle differences between current and voltage in addition to the current and voltage magnitude. Although I do not have any specific knowledge
about specific brands of PLCs I suspect that specialized input modules for precise phase measurements are available for many PLCs. You should contact the PLC manufacturer for this information.

However, there are specialized controllers for capacitor banks that are reasonably inexpensive that would probably cost less than a PLC approach (if cap bank control is all you want to perform). An internet search for "capacitor control", "VAR compensation", and similar terms will probably identify more suppliers than you have time to evaluate. Also check the product directories of your
favorite power magazine or web site (e.g. http://wwww.electricityforum.com).

Regards,
Ralph Mackiewicz
SISCO, Inc.

 

I Think it is impossible. because the controller for capacitor bank on/off needs the calculate power factor using current and voltage. because the plc has no ability to recieve this input directly from pt and ct, it needs to interface circuit which is not economical.