Power Systems Analysis

Comprehensive Power Systems Engineering

A well-designed electrical distribution system depends on accurate engineering analysis to ensure safety, code compliance, and reliable operation. Zech Engineering provides the full range of power systems studies needed to evaluate, optimize, and document your facility's electrical infrastructure.

Every study is performed using industry-standard software (SKM Power*Tools or ETAP), follows applicable IEEE and NEC standards, and is delivered as a PE-stamped engineering report.

Short-Circuit Analysis

Short-circuit analysis determines the available fault current at every point in your electrical distribution system. This data is essential for verifying that equipment ratings are adequate, sizing protective devices, and establishing the basis for arc flash calculations. For a deeper look at why this analysis matters, see our article on the importance of a short circuit study.

We calculate fault currents per IEEE 551 (Violet Book) and ANSI/IEEE C37 series standards, considering both maximum and minimum fault current scenarios. The analysis covers:

• Three-phase, line-to-ground, line-to-line, and double line-to-ground fault calculations
• Equipment duty evaluation — verifying that switchgear, panelboards, and buses are rated for available fault current
• Identification of under-rated equipment that requires replacement or upgrade
• Utility contribution analysis based on current fault current data from the serving utility

If equipment fault current ratings are exceeded, OSHA and NEC consider the equipment a recognized hazard. A short-circuit study identifies these conditions before they lead to catastrophic equipment failure — here's a real example of violations we uncovered during a recent study.

Protective Device Coordination Study

A coordination study evaluates the time-current characteristics of every protective device in your system — circuit breakers, fuses, relays, and motor overloads — to ensure they operate in the correct sequence during a fault. Proper coordination means the device closest to the fault trips first, minimizing the extent of the outage and protecting upstream equipment.

Poorly coordinated systems cause nuisance trips that shut down entire sections of a facility, or worse, leave downstream faults uncleared while upstream devices trip indiscriminately.

Our coordination study includes:

• Time-current curve (TCC) development for the entire system
• Recommended breaker trip settings and fuse selections
• Motor starting and damage curve analysis
• Transformer inrush and through-fault protection curves
• Cable and conductor damage curves
• Relay settings and recommendations for relay-based protection schemes

Load Flow Analysis

Load flow (power flow) analysis evaluates voltage profiles and power loading across your distribution system under normal and contingency operating conditions. This study identifies:

• Voltage drop issues that may affect sensitive equipment
• Overloaded transformers, feeders, or branch circuits
• Capacity for future load additions
• Optimal tap settings for transformers
• Power factor correction needs and capacitor bank sizing

Load flow analysis is particularly valuable when planning facility expansions, evaluating the impact of new equipment, or troubleshooting power quality problems.

Additional Studies

Motor Starting Analysis

Evaluates the voltage dip caused by large motor starts to determine whether starting methods (across-the-line, soft-start, VFD) are adequate and whether the voltage depression will affect other connected loads.

Harmonic Analysis

Identifies harmonic distortion from nonlinear loads (VFDs, UPS systems, LED lighting) and evaluates compliance with IEEE 519 limits. Includes filter design recommendations when needed.

Ground Fault Analysis

Studies the grounding system and evaluates ground fault detection and protection to ensure compliance with NEC Article 250 and appropriate ground fault clearing.

Deliverables

Every power systems study from Zech Engineering includes:

• PE-stamped engineering report with detailed results and recommendations
• Updated or verified one-line diagrams
• Complete calculation results in tabular format
• Time-current coordination curves (for coordination studies)
• Recommended protective device settings
• Executive summary written in clear, non-technical language for facility management