Secondary Electrical Design Software (SEDS)

Initially developed in 1998, the Secondary Electrical Design Software (SEDS) enables users to quickly layout a secondary design and easily assess performance measures such as voltage drop, flicker, loading and short circuit current using a customized load flow algorithm. SEDS includes load diversity in the calculations, and uses a sophisticated approach to calculate the coincident demand of dissimilar types or sizes of loads - a situation which can give silly results using conventional coincidence tables.

SEDS development benefited significantly from the testing, guidance, and input of the consortium member utilities. Development with such tight user integration resulted in a final product that provides significant flexibility and usability to the large number of utility planners all across the United States.


SEDS performs a variety of calculations for both single-phase and three-phase systems:

Single Phase Analysis:

  • Distribution transformer coincident loading
  • Secondary cable loading coincident current
  • Secondary service voltages
  • Mutual and self flicker
  • Service-entrance short circuit currents
  • Cold load pickup guidelines
  • Optimization based upon first cost or first order total owning cost

Three Phase Analysis:

  • Distribution transformer loading
  • Secondary cable loading
  • Secondary service voltages
  • Voltage unbalance
  • Mutual and self flicker
  • Service-entrance short circuit currents


The recently developed optimization algorithm uses a member utility’s existing SEDS database, and employs a unique method to improve overall computational time while always finding the best solution in a defined pragmatic space. The optimization objective function can be set for lowest first cost or lowest total owning cost taking into account overall secondary system losses. SEDS is the ideal software package for helping planners design the most efficient secondary systems using standard equipment (transformers and secondary conductors) while meeting technical service requirements.



SEDS data selections are customizable, similar to the DSTAR Engineering Toolbox. The Administrator sets up the database with standard load types, cables, and transformers. Also, motor types for flicker calculations and coincidence factor categories are also set up by the Administrator. The user simply clicks on one of these standard types, or can directly input data. The administrator can also customize the images used for each component represented in SEDS. To save the user the effort of specifying equipment over and over again, SEDS provides a "data copy" function which transfers the specifications from one load or cable to another with a simple mouse click on the graphic object.

Who Should Use:

Distribution Planners, Designers, Standards Engineers, Power Quality and Reliability Engineers

SEDS was created, modified, and enhanced in the following projects:
P7-2, P9-6, P10-15, P11-4, P12-2, P13-4, P16-4