## myCableEngineering Calculation Method

Calculation of Impedance is reasonably involved. Other notes give an insight into the individual calculations.

With myCableEngienering, the calculation will typically follow the following procedure

**d.c. resistance**- is determined using IEC 60288. For any cases in which IEC 60228 is not suitable, the resistance is obtained using CENELEC CLC/TR 50480. See also Conductor Resistance.**temperature adjustment**- the calculated d.c. is adjusted so that is value is accurate relative to the operating temperature of the conductor.**a.c. resistance**- the a.c. resistance is obtained by applying skin and proximity effect factors as defined in IEC 60287. See also Conductor Resistance.**positive and zero sequence impedance**- are calculated using the methods give in IEC 60909 and resistance values calculated above. See also Impedance.

### Resistance, Reactance

Positive and zero sequence impedance calculated above, are in complex form. The real part of the impedance gives the resistance and the imaginary part the reactance.

### Capacitive Reactance

Currently we do not calculate capacitive reactance. This will likely be added as the application grows and develops the need for this calculation.

### Impedance Equations

Impedance equations are presented in details in Impedance. Depending on the type of cable, number of cores and system type the following equations are applied:

Cores: | 1 | 2 | 3 | 4 | 5 |
---|---|---|---|---|---|

Unscreened Cables | |||||

None | 10/11 | 10/11 | 10/11 | 10/11 | 10/11 |

TN-S | 10/11 | 10/11 | 10/11 | 10/11 | 10/11 |

TN-C-S | 10/14 | 10/14 | 10/14 | 10/14 | 10/14 |

TT | 10/11 | 10/11 | 10/11 | 10/11 | 10/11 |

IT | 10/inf | 10/inf | 10/inf | 10/inf | 10/inf |

Screened Cables |
|||||

None | 15/16 | 15/32 | 15/32 | 15/32 | 15/32 |

TN-S | 15/32 | 15/32 | 15/32 | 15/32 | 15/32 |

TN-C-S | 15/28 | 15/28 | 15/28 | 15/28 | 15/28 |

TT | 15/16 | 15/32 | 15/32 | 15/32 | 15/32 |

IT | 15/inf | 15/inf | 15/inf | 15/inf | 15/inf |

Equations Z1/Z0 - for a.c. cables (refer Impedance)

Note: for armoured cables, the armouring and earth are always considered as part of the earth return path. Excepting TN-C-S, earth return through a spare internal conductor is not considered.

Note: current return through a spare internal conductor for low voltage cables is on our features list to be added