19-06-2010, 07:50 PM
Digital Microprocessor Power Factor Controller
Evaluation of the reactive load is achieved by taking instantaneous
measurements in all four quadrants of voltage and current. Then the the active and reactive components of the power are obtained by digitalized the values in the microprocessor and continuously
evaluating the components. cos phi ie the power factor is calculated from these two values.If the load deviates from the target power factor, then a 'trial switching' will be made on the as yet 'unknown Capacitor Step Values'. the value of each capacitor forms a learnig curve. after that it is It is no longer necessary to manually select the starting
current or C/k value. The value of each capacitor step will be
evaluated by the relay and stored in its memory permanently thus forming the learning curve. The relay will select from the bank of capacitors available the
step(s) which are necessary in order to achieve the required level
of reactive compensation. defective capacitor steps or unconnected ones will be ignored. three attempts will be made to
check any previously reported failed capacitor step.If the fuses
have been replaced , then that step too can then be brought
back into the reactive compensation calculation.The relay will automatically select from its memory the
most appropriate cap step size and hence no fixed switching programs are required.
Target Power Factor Setting:
The function switch is used to adjust this. The target cos phi can be precisely selected on the digital display
using the + / - buttons.
Step Switching Time:
the precise switching time can be selected using this function. Shorter switching times can be selected when
required.
Digital cos phi Indication:
the digital indicator will display the instantaneous value of the system power factor.
Alarm Internal Fault Signaling:
if there are insufficient capacitors to achieve the target power factor or due to any other problem , then an internal alarm will be triggered. for more details, refer this pdf:
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