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In the Power Frequency Calculation window the file xVerifyF.lis is read and displayed.

 

The  Power Frequency Calculation data case is specified under Select type of Verify. It results in a printed lis-file containing information on the short circuit impedance and the reactive power open circuit power flow.

 

•Zero sequence short circuit impedance (real and imaginary part). Z0 = R0 + jX0.

Each phase of a circuit is connected to a 1 V amplitude voltage source with zero phase angle. The other end of the line is grounded. Z0 is calculated as the inverse of the injected current divided by the number of phases in the circuit. All phase conductors of other phases are open.

 

•Positive sequence short circuit impedance (real and imaginary part). Z+ = R+ + jX+.

The phases of a circuit are connected to a 1 V amplitude voltage source with phase angle -360*(i-1)/n where i is the phase number (1,2,3..) and n is the number of phases of the tested circuit.

The other end of the line is grounded.

Z+ is calculated as the inverse of the positive sequence current.

All phase conductors of other phases are open.

 

•Zero sequence line charging. Q0

Each phase of a circuit is connected to a 1 V amplitude voltage source with zero phase angle.

The other end of the line is open.

Q0 is the injected reactive power multiplied by the square of the user specified base voltage (multiplied with 2/n).

All phase conductors of other phases are open.

 

•Positive sequence line charging. Q+

The phases of a circuit are connected to a 1 V amplitude voltage source with phase angle -360*(i-1)/n where i is the phase number and n is the number of phases of the tested circuit.

The other end of the line is open.

Q+ is calculated as the average injected reactive power multiplied by the square of the user specified base voltage (multiplied with 2/n).

All phase conductors of other phases are open.

 

•Mutual zero sequence impedance (real and imaginary part). Z00 = R00 + jX00.

Each phase of the i'th circuit is connected to a 1 A amplitude current source with zero phase angle.

The receiving end of the circuits i and j is grounded.

The j'th circuit is short-circuited and open in the sending end.

Z00 is calculated as the voltage at the sending end of the j'th circuit

The process is repeated for all circuits.

All phase conductors of phases not belonging to the i'th and j'th circuit are open.

 

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