The damping of transient phenomena during a transient simulation is due to 2 causes: Physical damping and numerical damping.

- The physical damping is due to the behaviour of the modeled electrical system. The attached example shows a network with a single busbar and a single R-L-C shunt. The shunt is short-circuited, showing swings on its own afterwards.
The swinging of the shunt is described by:

freq = 2 * pi * sqrt((4 * L/C - R^2)/(2 * L)) = 1000Hz

Damping time constants = 2 * L/R = 24ms

The simulation shows a (correct) damping result of transient behaviour of about 5% in 72ms. The calculation case for physical damping in the attached example has all numeric calculation options correctly set, and the simulation therefore shows the correct transient behaviour of the swinging shunt.

- The numerical damping is due to the numerical integration, and may be larger than 0.0. Numerical damping may be due to a too-large step size or a too-small damping factor. The effects of a too small damping factor are shown in the study case SmallDamp. The shunt resistance has been set to zero, which should show an undamped behaviour. The damping factor for the simulation, however, has been set to 0.8 on the advanced options page of the initial condition command. Resulting in a damped behaviour.

The effects of a too-large step size are demonstrated in the study case, SmallStep. The resistance is again zero, but the step size has been increased by a factor of 100, leading to damped behaviour. The damping factor for the simulation is normally set to a value close to 1.0; this value represents a normal (undamped) trapezoidal method, and a value of 0.0 represents a (damped) Newton method. Damping is typically set to a value less than 1.0 to avoid numerical oscillations.