Primary Ohms to Secondary Ohms Conversion
Convert a primary impedance value to a secondary impedance value by :
1. multiply the primary impedance value by the CT ratio.
2. divide this number by the PT ratio.
Secondary Ohms to Primary Ohms Conversion
Convert from secondary to primary by:
1. multiply the secondary impedance value by the PT ratio
2. divide this number by the CT ratio.
Many times the line impedance data might be specified in primary values.
A good relay tech can easily verify or derive the secondary impedance value that will be used to set impedance relays.