In addition to the previous article, we will consider an example of compiling a network model with isolated neutral. Consider the simplest power line with one-way power supply (Fig. 1). It is necessary to draw up a power transmission model that will give out currents and voltages at the beginning of the line in short circuit modes and in single-phase earth fault modes.

# Category: Phase coordinates method

The phase coordinate method for modeling electrical networks with a grounded and isolated neutral, calculation of short circuit currents.

## Phase Coordinates Method: Application for Isolated Neutral Networks

The phase coordinate method allows you to simulate networks with isolated neutral. In Russia, networks of 6-10-35 kV (sometimes 110 kV) operate with isolated neutral. Such networks are accompanied by small currents and significant overvoltages during single-phase earth faults.

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## Phase Coordinates Method: Wire Transposition

According to the “Electrical Installation Rules”, one full transposition cycle should be performed on overhead power transmission lines with a voltage of 110-500 kV and a length of more than 100 km to limit asymmetry of currents and voltages.

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## Phase Coordinates Method: An Example of Compiling a Network Model

Consider an example of compiling a power transmission model using the phase coordinate method. In fig. 1 shows the power transmission, a mathematical model of which must be compiled. It is necessary to determine the currents in the short circuit mode at the beginning of the line.

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## Phase Coordinates Method: Short Circuit with Break Model

Some complex types of damage can occur in power lines, for example, a short circuit with a wire break. This mode can occur when a wire of any phase falls to the ground (Fig. 1).

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