Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
Question Is it possible to employ a smoothly variable capacitor bank
in an induction motor in order to control its power factor
during variations in its load.
Answer Here is a primer on the causes and cures of power factor. You may skip this if you already know these basic principles:
The wikipedia explanation may be helpful for you also:
An automatic power factor correction unit is used to improve power factor. A power factor correction unit usually consists of a number of capacitors that are switched by means of contactors. These contactors are controlled by a regulator that measures power factor in an electrical network. To be able to measure power factor, the regulator uses a current transformer to measure the current in one phase.
Depending on the load and power factor of the network, the power factor controller will switch the necessary blocks of capacitors in steps to make sure the power factor stays above a selected value (usually demanded by the energy supplier), say 0.9.
Instead of using a set of switched capacitors, an unloaded synchronous motor can supply reactive power. The reactive power drawn by the synchronous motor is a function of its field excitation. This is referred to as a synchronous condenser. It is started and connected to the electrical network. It operates at full leading power factor and puts vars onto the network as required to support a system’s voltage or to maintain the system power factor at a specified level. This is found at: http://en.wikipedia.org/wiki/Power_factor
Hope the reading is not to taxing for you.
Let me know if you have some questions later on.
C
PS: The word "smoothly variable" is hard to accomplish without a complex control circuit that is found the big panels where cost justifies the use of computer generated measurements and alteration of current angles to keep pf constant. Dynamic adjustment is hard to do easily.
