# Ncees power 30



## yaoyaodes (Dec 2, 2021)

Can anyone explain this? The answer shows B with reference 460.9
460.9 Rating or Setting of Motor Overload Device. Where a motor installation includes a capacitor connected on the load side of the motor overload device, the rating or setting of the motor overload device shall be based on the improved power factor of the motor circuit. The effect of the capacitor shall be disregarded in determin‐ ing the motor circuit conductor rating in accordance with 430.22.

that 460.9, I don't know which part indicates that we should pick B.


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## main197 (Dec 3, 2021)

Before adding the capacitor, all the current needs to be supplied by the source (including reactive current). When you add capacitor on the load side of the motor, reactive current drawn by the motor is provided by the capacitor. So, the total current flowing in the motor circuit up to the capacitor is reduced(reactive current flows from the load side capacitor into the motor). So, less than full load current flows through the OL relay. The rule says that the setting should be based on the improved power factor i.e. lower current. Since less current flows through the OL relay, the setting needs to be reduced. 

The setting would not change if it was connected on the line side.


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## yaoyaodes (Dec 13, 2021)

main197 said:


> Before adding the capacitor, all the current needs to be supplied by the source (including reactive current). When you add capacitor on the load side of the motor, reactive current drawn by the motor is provided by the capacitor. So, the total current flowing in the motor circuit up to the capacitor is reduced(reactive current flows from the load side capacitor into the motor). So, less than full load current flows through the OL relay. The rule says that the setting should be based on the improved power factor i.e. lower current. Since less current flows through the OL relay, the setting needs to be reduced.
> 
> The setting would not change if it was connected on the line side.


I made mistake. I thought the contactor was the capacitor. Thanks


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