Unbalanced/Single-Phase Study Module

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.

Benefits:

• 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.