SKM Systems Analysis are a California-based corporation that develop Power*Tools for Windows (PTW), an integrated suite of power systems analysis tools aimed at industrial systems. The original software, called DAPPER, was first released in 1978, though the initial version of PTW wasn't released until 1995.

Functions include load flow, short circuit, demand load analysis, OPF, load schedules, feeder and transformer sizing, protection coordination (CAPTOR), arc flash analysis, transient motor starting (TMS), harmonic analysis (HI_WAVE), transient stability (I*SIM), distribution reliability, earth grid design (GroundMat), dc load flow and short circuit analysis, battery sizing, cable pulling analysis and equipment evaluation.

Reference: SKM