Project Library
Please explain why the per unit values for motors, are based on a system base kVA and for transformers, the per unit values are based on the system kVA. It seems that the per unit values for the motors and transformers when entered in the project library should be compatible with any system kVA? Is it neccessary to enter motors and transformers based on the kVA of the system? Therefore there would be multiple transfomer inputs with different per unit values depending on the system kVA that will be used.

For example, the following transformer is entered into EDSA transformer library
15kVA
R = 0.0027pu
X = 0.00465pu
When the Data Entry Format is changed to Actual Values, R% = 0.00040 and X% = 0.00070.
Based on a system kVA of 10000 kVA which is shown in the Master File Editor, these values are correct.

However, if the system kVA is changed to 100 MVA in the Master File Editor, R% and X% should also change but they do not. Should the values in the transformer library correspond to a 100MVA system or does the library for the transformers always use a 10000kVA system? If not, what is the system kVA used by the transformer library and can it be changed? Do I have to re-enter the transformer using per unit values for a 100 MVA system?

Per unit in editor is always based on the system kVA. Percent (%) is however based on the device kVA. In libraries, R and X are in percent or ohms, associated only with the device itself, not with system kVA. In your transformer case, X = 0.00465 pu is in per unit and so it is based on the system kVA of 100000 kVA. If it is changed to Percent, the number will be X = 0.00465 * 15 / 10000 * 100 = 0.0007 (%) as you indicated. If you save it into the library, X = 0.0007 % will be saved. Changing system kVA will not change the R and X in percent, but the values in per unit.