Power Calculation Algorithm

Presentation

The algorithms are given for the 3-wattmeter calculation method. The power definitions and calculation are given for a network with harmonics.

Calculated quantities are displayed:

oOn the MicroLogic X display screen, at Home > Measures > Power (total power only)

oWith EcoStruxure Power Commission software

oWith the EcoStruxure Power Device app (total power only)

oOn a remote controller using the communication network

Active Powers

The active power for each phase is calculated as follows:

 

The total active power is calculated as follows:

 

Reactive Power

The reactive power with harmonics for each phase is calculated as follows:

 

The total reactive power is calculated as follows:

oWith vector method:

 

oWith arithmetic method:

 

Apparent Power

The apparent power for each phase and total apparent power is calculated as follows:

Sp = (Vp x Ip) where p = 1, 2, 3 (phase)

The apparent power for each phase and total apparent power is calculated as follows:

oWith vector method:

 

oWith arithmetic method:

 

ENVT Wiring and Configuration on 3-Pole Circuit Breaker

When installed on a system with distributed neutral, correct ENVT wiring and configuration are necessary to calculate and display correct values per phase.

When installed on a system without distributed neutral, if ENVT is configured to Yes, power values per phase are not relevant.

The following table indicates the displayed and calculated values for each configuration: