CEE Relays Ltd

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Unbalanced / Single-Phase Study Module
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PTW Unbalanced Studies simulates systems with single-phase, two-phase and unbalanced three-phase load conditions. Phase and sequence currents can be displayed for different operating and load conditions including open-phase and simultaneous faults. Studies include demand load analysis, sizing, load flow/voltage drop and short circuit. Reports also include three-phase and single-phase panel schedules. Modeling includes single-phase, two-phase and three-phase lines, transformers, loads, and capacitors as well as single-phase mid-tap transformers.

A downloadable version of the Unbalanced Study Module brochure is available in PDF format via a link at the bottom of this page. 
  • Design better systems where single-phase distribution and unbalanced conditions may exist. 
  • Identify undersized circuits caused by unbalanced loads before problems occur. 
  • Set negative sequence relays based on unbalanced fault and load simulations to identify problems that would otherwise go undetected until damage occurs. 
  • Communicate designs more easily with professional reports and graphs. 
  • Evaluate alternatives quickly and easily to establish an optimal design.
Interface Options
  • Display phase or sequence values with magnitude only, magnitude and angle, magnitude and power factor, or real and imaginary. 
  • Display individual phase values, maximum phase, or phase summation. 
  • Represent any combination of 1-phase, 2-phase and 3-phase systems including systems with mid-tap transformers. 
  • Shares common interface with balanced DAPPER studies, harmonic analysis, transient stability, equipment evaluation, reliability, and CAPTOR protective coordination modules.
Analysis Options
  • Connected, demand and design load analysis for each phase. 
  • Cable and transformer sizing based on design load of largest phase. 
  • Load flow and voltage drop through each 1-phase, 2-phase, and 3-phase branch. 
  • Representation of transformer automatic Load-Tap-Change (LTC) options. 
  • Representation of mid-tap transformers. 
  • Representation of transformer no-load losses. 
  • Short circuit calculations including individual or simultaneous faults at different locations and on any phase combinations. 
  • Optional capacitance to earth representation. 
  • Unbalanced load representation in three-phase and single-phase panels and sub-feeds. 
  • Cable parameter calculator. 
  • Sequence to Phase and Phase to Sequence impedance conversions. 
  • Transmission line parameter calculator including multiple circuits, bundling, transposition, and line sag effects.
Typical Applications
  • City distribution systems with three-phase and single-phase feeds. 
  • Rural utility distribution systems with three-phase and single-phase feeds. 
  • Campus distribution systems. 
  • Industrial plants to identify normal and abnormal unbalanced conditions. 
  • Commercial and institutional buildings with three-phase and single-phase loads and panels. 
  • Setting negative sequence relays to detect abnormal unbalanced conditions.
A downloadable version of the Unbalanced module brochure is available here.
PDF 0.1Mb