PowerPivot–Enable Logging

For enabling Verbose Logging follow these steps -

Go to Central Admin and Click on Monitoring

Click on Configure Diagnostic Logging

Enable Verbose Logging as shown below – Here I have enabled Logging for Excel and PowerPivot

Set  Least Critical Event to report to the Event Log and Trace Log to Verbose as shown below and Click OK

 

 

Further Ref -

https://technet.microsoft.com/en-us/library/ee210681(v=sql.105).aspx