Three-phase circuit parameter meter (U, I, P, S, PF)#

The Three-phase circuit parameter meter (U, I, P, S, PF) block is used to calculate several parameters of an electrical three-phase three-wire circuit.

Note

The outputs of the block with calculated signals are represented as vectors, so they must be connected to the Demux block with the corresponding number of outputs.

The circuit parameters are calculated based on the following measured values:

instantaneous values of line voltages \(u_{AB}, u_{BC}, u_{CA}\), which are determined using voltmeters connected between the corresponding phases;
instantaneous values of phase currents \(i_A, i_B, i_C\), which are determined using ammeters on the corresponding phases.

The block calculates the following parameters:

effective values of phase currents according to formulas (1) :

(1)#\[\begin{split}I_{Arms}=\sqrt{\frac{1}{T}\cdot \int^T_0i^2_A\cdot dt}\\I_{Brms}=\sqrt{\frac{1}{T}\cdot \int^T_0i^2_B\cdot dt}\\I_{Crms}=\sqrt{\frac{1}{T}\cdot \int^T_0i^2_C\cdot dt}\end{split}\]

instantaneous values of phase voltages according to formulas (2) :

(2)#\[\begin{split}u_A=\frac{u_{AB}-u_{CA}}{3}\\u_B=\frac{u_{BC}-u_{AB}}{3}\\u_C=\frac{u_{CA}-u_{BC}}{3}\end{split}\]

effective values of phase voltages according to formulas (3):

(3)#\[\begin{split}U_{Arms}=\sqrt{\frac{1}{T}\cdot \int^T_0u^2_A\cdot dt}\\U_{Brms}=\sqrt{\frac{1}{T}\cdot \int^T_0u^2_B\cdot dt}\\U_{Crms}=\sqrt{\frac{1}{T}\cdot \int^T_0u^2_C\cdot dt}\end{split}\]

active power of each phase and the sum of the phases according to the formulas (4) :

(4)#\[\begin{split}P_A=\frac{1}{T}\cdot \int^T_0u_A \cdot i_A \cdot dt\\P_B=\frac{1}{T}\cdot \int^T_0u_B \cdot i_B \cdot dt\\P_C=\frac{1}{T}\cdot \int^T_0u_C \cdot i_C \cdot dt\\P_{\Sigma}=P_A+P_B+P_C\end{split}\]

the total power of each phase and the sum of the phases according to the formulas (5) :

(5)#\[\begin{split}S_A=U_{Arms}\cdot I_{Arms}\\S_B=U_{Brms}\cdot I_{Brms}\\S_C=U_{Crms}\cdot I_{Crms}\\S_{\Sigma}=S_A+S_B+S_C\end{split}\]

phase power factor according to formulas (6) :

(6)#\[\begin{split}K_{MA}=\frac{P_A}{S_A}\\K_{MB}=\frac{P_B}{S_B}\\K_{MC}=\frac{P_C}{S_C}\end{split}\]

1. Properties#

Property	Default Value	Description	Units of measurement
Fundamental harmonic frequency	50	–	Hz

2. Inputs and outputs#

Parameters	Input/Output	Description	Units of measurement	Port type
A	Input	Phase A input	–	Electronics
B	Input	Phase B input	–	Electronics
C	Input	Phase C input	–	Electronics
a	Output	Phase A output	–	Electronics
b	Output	Phase B output	–	Electronics
c	Output	Phase B output	–	Electronics
Instantaneous values of phase currents	Output	Vector of three signals: \(i_A, i_B, i_C\)	А	Automation
Effective values of phase currents	Output	Vector of three signals: \(I_{Arms}, I_{Brms}, I_{Crms}\)	А	Automation
Instantaneous values of phase voltages	Output	Vector of three signals: \(u_A, u_B, u_C\)	V	Automation
Effective values of phase voltages	Output	Vector of three signals: \(U_{Arms}, U_{Brms}, U_{Crms}\)	V	Automation
Active power	Output	Vector of four signals: \(P_A, P_B, P_C, P_{\Sigma}\)	W	Automation
Apparent power	Output	Vector of four signals: \(S_A, S_B, S_C, S_{\Sigma}\)	VA	Automation
Power factor	Output	Vector of three signals: \(K_{MA}, K_{MB}, K_{MC}\)	p.u.	Automation

Note

To separate vector signals, it is necessary to use a demultiplexer.

In order to see the connection capabilities of the block, you need to go to page Description of block ports