This tab appears for plant power cables only. You can specify parameters for cable grounding using the cable armor or using a separate grounding cable, as well as external impedance, and the software can calculate the total earth loop impedance for the cable.
Earth loop impedance calculation required
Select this option when you want to calculate the earth loop impedance for this particular line. After you select Calculate, the software clears this check box.
Cable impedance path
Allows you to specify the grounding path used for the cable using the cable armor or via a separate grounding cable, if available.
Use cable armor
When you select this option, the software uses the cable armor as the return path for grounding with the values that you specify for the armor resistance and reactance to calculate the earth loop impedance.
Armor impedance per unit length
Displays the overall armor impedance per unit length, which the software calculates from the Armor Reactance and Armor Resistivity properties as specified in the Properties window.
Actual cable length
The value of the Actual length property that the software calculates on the Design Data tab.
Total armor impedance
The total cable armor impedance, calculated as the product of the armor impedance per unit length and the actual cable length.
Use separate grounding cable
When you select this option, the software uses a grounding cable that is associated with the load as the return path for grounding with the values that you specify for the grounding cable resistance and reactance to calculate the earth loop impedance. Note that this option is only available if a grounding cable is already associated with the load on the To side of the power cable.
Tag
The item tag of the grounding cable associated with the load on the To side of the power cable.
Cable formation
Displays the cable formation of the grounding cable as specified in the cable common properties.
Cable impedance per unit length
Displays the overall grounding impedance per unit length, comprised of the Reactance per unit length and Resistivity per unit length properties which are specified for the grounding cable.
Actual cable length
The value of the Actual length property for the grounding cable.
Total grounding cable impedance
The grounding cable impedance, calculated as the product of the cable impedance per unit length and the actual cable length.
External loop impedance
Allows you to type a value for any additional impedance associated with the power source.
Total earth loop impedance
The total impedance, calculated as the sum of the grounding path impedance, external loop impedance, and impedance of the cable carrying the current.
Calculate
Select to update the calculation of the total earth loop impedance.
System notes
Displays messages related to earth loop impedance calculations.
Command Button
Synchronize With Reference
Opens the Synchronize Plant and Reference Cable Data Dialog, which enables you to see if there are any differences between the values in the properties of the current plant cable and the values in the associated reference cable. You can then copy the reference data to the plant cable so that the plant and reference cable data is fully synchronized. Note that this command becomes available only when there is a difference between plant and reference data for the current item.