# Initial Cycles and Simulation Start Time in Steady-State Analysis

**URL:** <https://forum.plexim.com/t/initial-cycles-and-simulation-start-time-in-steady-state-analysis/3342>\
**Category:** General\
**Created:** [October 12, 2026, 10:44am UTC](https://forum.plexim.com/t/initial-cycles-and-simulation-start-time-in-steady-state-analysis/3342 "2026-10-12T10:44:15Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![CJB](https://avatars.discourse-cdn.com/v4/letter/c/a4c791/32.png) [@CJB](https://forum.plexim.com/u/CJB)\
**Post date:** [October 12, 2026, 10:44am UTC](https://forum.plexim.com/t/initial-cycles-and-simulation-start-time-in-steady-state-analysis/3342/1 "2026-10-12T10:44:15Z")

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Hello!  
I am trying to work with the Analysis Tools in Standalone, and I started with the Steady-State Analysis with a simple RC circuit.

[RCCircuit.plecs](https://forum.plexim.com/uploads/short-url/6KLyKLHi2xcKdhWga1ruoZy4pvx.plecs) (12.2 KB)

In the circuit, during 0-1s there is a constant voltage, and during 1-2s a sinusoidal voltage.  
For the a Simulation Start Time at 0s I get a constant voltage, and at 1s a sinusoidal voltage, as expected.

However, when I change the Initial cycles to 2 or higher, with Simulation Start Time at 0s, I get the following figure:

 ![image](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/2X/4/4763daca71bc52b061ed667e43bad521929fa66a.png)  
I am surprised because when I set Initial cycles to 50, with a system period of 0.02s, I would expect the same plot as for the one of Simulation Start Time at 1 s. Why does it look different?

The reason I am asking this is because I want to apply this on a more complex circuit that requires an initialisation process, and I was planning to set the Simulation start at 0s and then the required initial cycles.

Thank you,  
Carles

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**Author:** ![RetoChristen](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/retochristen/32/1225_2.png) [@RetoChristen](https://forum.plexim.com/u/RetoChristen)\
**Post date:** [October 13, 2026, 11:55am UTC](https://forum.plexim.com/t/initial-cycles-and-simulation-start-time-in-steady-state-analysis/3342/2 "2026-10-13T11:55:46Z")

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Hi,

The important distinction is that the **Initial cycles** parameter does not advance the simulation time by N × T. Instead, the Steady-State Analysis repeatedly simulates the same system period while updating the initial conditions between iterations.

For example, with a system period of T = 0.02 s:

- **Simulation Start Time = 0 s:** Each initial cycle runs from 0 to 0.02 s.

- **Simulation Start Time = 1 s:** Each initial cycle runs from 1 to 1.02 s.

- **Initial cycles = 50:** The same time interval is simulated 50 times, using the final states of one cycle as the initial states of the next.

Therefore, setting the Simulation Start Time to 0 s with 50 initial cycles is **not equivalent** to running a continuous simulation from 0 to 1 s.

This also explains the behavior you are observing. Since your voltage source changes its behavior at t = 1 s, increasing the number of initial cycles will not move the analysis into the sinusoidal portion of the source signal.

In your case, you should set the **Simulation Start Time** to a point where the system has entered its intended periodic operating mode.