Device for Measuring an Amount of Capacitance to Correct a Power Factor of a Running Electric Motor

Abstract

A device for measuring an amount of capacitance to correct a power factor of a running electric motor includes a three-phase bus for connection to the electric motor; a metering device operably connected to the three-phase bus for displaying KVAR, the metering device including a display for displaying power factor, voltage, current, frequency, active energy, reactive energy, active power, reactive power, apparent power or maximum demand of the motor; a plurality of switched delta-configured capacitor circuits operably connected to the three-phase bus, each of the switched delta-connected capacitor circuits having different capacitance values; and a plurality of switches, each of the switches being operably associated with a respective one of the switched delta-configured capacitor circuits to connect to the three-phase bus the respective one of the switched delta-connected capacitor circuit to minimize the KVAR reading.

We claim: 
     
         1 . A device for measuring an amount of capacitance to correct a power factor of a running electric motor, comprising:
 a three-phase bus for connection to the electric motor;   a metering device operably connected to said three-phase bus, said metering device including a display for displaying power factor, voltage, current, frequency, active energy, reactive energy, active power, reactive power, apparent power or maximum demand of the motor;   a plurality of delta-configured capacitor circuits operably connected to said three-phase bus, each of said switched delta-connected capacitor circuits having different capacitance values; and   a plurality of switches, each of said switches being operably associated with a respective one of said delta-configured capacitor circuits to connect to said three-phase bus said respective one of said delta-connected capacitor circuit to improve the power factor of the electric motor.   
     
     
         2 . A device as in  claim 1 , wherein:
 said device includes a housing with a front panel; and   said display is disposed on said front panel.   
     
     
         3 . A device as in  claim 1 , wherein said housing is a rectangular hermetically-sealed NEMA 3R Indoor/Outdoor steel case. 
     
     
         4 . A device as in  claim 1 , wherein said plurality of switches include respective pilot lights. 
     
     
         5 . A device as in  claim 1 , wherein each of said delta-configured capacitor circuit includes three equal value capacitors. 
     
     
         6 . A device as in  claim 5 , wherein said delta-configured capacitor circuits comprises 7 capacitor circuits with capacitors with the following capacitance values: C1=6 μF, C2=15 μF, C3=30 μF, C4=60 μF, C5=60 μF, C6=60 μF, and C7=70 μF.