Why is my macro to compute average power not equalling zero? Theory says
that the average power for a capacitor is zero.
Your macro calculates power based on current and voltage, which are slightly out of sync since you are using an electrostatic element which solves for charge and computes current by a numerical derivative over two time steps. Due to this the current value is half a time step behind the voltage. To investigate this possibility I modified your current array to be the average of the values at t and t+1 as follows: Current(iii) = (Current(iii) + Current(iii+1))/2 I then computed power by multiplying the current array by the voltage array with *VOPER. The mean value of this calculation (calculated by VSCFUN) is quite small as shown below. It is also possible to produce the negative bias in the power with the apdl multiplication of slightly out of phase sin and cos functions as shown below. fini /clear *afun,deg *dim,sin_cos,table,100,1 *vfill,sin_cos(1,0),ramp,0,.01 *do,iii,1,100 sin_cos(iii,1)=0.1e2*cos(iii*360/1001.8)*2.56*sin(iii*360/100) *enddo *vplot,sin_cos(1,0),sin_cos(1,1) *vscfun,mean_value,mean,sin_cos(1) 

