Check Relay Loadability at 0.85 per-unit voltage using ratings in MVA

In OneLiner v15.4 or earlier when the ratings of lines and transformers are entered in the unit of MVA, the Check Relay Loadability command calculates the highest level of load current that the relay should not trip by assuming the load is constant-MVA. For studies done at 0.85 per-unit voltage, this results in a current that is 1/0.85 or about 17.6% higher than the load current at the voltage of 1.0 per-unit.  

The latest version of PRC-023 standard requires a slightly different method of computing the limit when the rating is stated in MVA.  Under PRC-023-2, OneLiner has to compute the load current that the relay should not trip by assuming the voltage is 1.0 per-unit. This method is used in OneLiner v15.5 or later.

When the ratings of lines are specified in the unit of amperes, the Check Relay Loadability command uses the values that you entered in the Line data dialog box with no adjustment for the operating voltage level.  This method is in use in all versions of OneLiner.