Square D by Schneider Electric – Power System Analytical Studies
There’s more to managing an electrical system than troubleshooting problems. It also involves identifying potential issues and either eliminating or mitigating their effects. The analysis and diagnosis of any engineered system guards against improper system operation and the possibility of catastrophic losses.
- Managing an electrical system and the energy it delivers requires:
- A comprehensive understanding of the system’s normal and abnormal operation
- Knowledge of a wide variety of equipment
- The successful application of industry codes and standards
Our analytical studies help ensure your electrical system operates as it was designed and intended. Each study includes a detailed report of findings along with corrective recommendations to help maximize the reliability and operational efficiency of your system.
Protective device time-current coordination analysis
Short circuit analysis
Load flow analysis
Motor starting analysis
Switching transient modeling and analysis
Substation ground grid analysis
Protective Device Time-Current Coordination Analysis
The goals of a protective device time-current coordination analysis are to:
- Provide power equipment with the required protection
- Minimize service interruption under overload or short circuit conditions
This analysis evaluates an electrical system’s protective devices, including relays, fuses, and circuit breakers, and the equipment to which they are applied. The final report includes suggested settings for all adjustable devices. Composite log-log characteristic curves illustrating the resulting protection and system coordination are also provided.
- Minimizes system downtime and nuisance device operations
- Increases system protection and reduces equipment damage
- Isolates faulty circuits without loss of power to other parts of the system
- Optimizes the protective device setting for reliability and arc flash protection
Short Circuit Analysis
This analysis calculates the fault current levels throughout the electrical network. The interrupting duties of the devices being analyzed are compared with the available fault currents. Where underrated equipment is identified, recommendations are provided to help you comply with industry codes and standards. The final report includes tables comparing short circuit levels to the rating of the equipment with recommendations for improvements. A computer-generated single-line diagram of the distribution system is also provided.
- Reduces system downtime
- Addresses concerns about underrated or misapplied equipment
- Minimizes or eliminates equipment damage
- Promotes electrical workplace safety
Load Flow Analysis
A load flow analysis addresses present electrical system deficiencies or identifies system requirements to meet future demand.
- Optimizes loading of the electrical distribution equipment
- Establishes reactive power flows needed to stabilize bus voltages
- Determines transformer tap settings
Our load flow experts translate design load data or field measurements into an accurate system model. Key system parameters are then calculated and the results of various scenarios are distilled into easy-to-understand tabulations.
- Minimizes downtime by stabilizing system voltages
- Prevents (or corrects) overloaded transformers and conductors
- Optimizes equipment utilization by evenly distributing plant load
- Prevents load-related nuisance tripping
- Improves power factor and avoids power factor penalties from utility
Harmonics cause power quality problems that can reduce system efficiency and increase operating costs. Found traditionally in industrial processes, harmonics are now present in both commercial and industrial facilities due to the proliferation of non-linear loads (power electronic equipment, variable speed drives, and switched-mode power supplies). The harmonic analysis results are presented in easy-to-understand tables. Explanations are provided to highlight the issues uncovered.
- Prevents equipment overheating
- Allows seamless interaction between loads and generators
- Reduces or eliminates undesirable voltage distortion levels
- Complies with IEEE 519 harmonic limits
Motor Starting Analysis
Starting large motors across the line can cause severe disturbances to the motor and any locally connected loads. The most significant effect is the voltage sag, which extends the acceleration time of the motor being started and causes additional thermal and mechanical stresses. Voltage sags also impact other loads connected to the power system, particularly electronic loads. A motor starting analysis must be made if the motor’s size > 30% of the supply transformer’s base kVA rating. Studies are also recommended if several smaller motors are started together or if the power source is a local generator. This analysis calculates the electrical parameters (voltage and current) and the accelerating torque of the motor during the starting process.
- Extends motor life by reducing starting thermal stresses
- Prevents the negative effects of voltage sags on other equipment
- Eliminates undesirable interactions between motors and generators
- Complies with the utility’s motor starting requirements
Switching Transient Modeling and Analysis
Normal or abnormal switching and circuit breaker operations cause transient conditions in power systems. Though transients have a brief time span, the resulting voltages may damage insulation or make sensitive electronic devices malfunction. Large magnitude currents can cause equipment overheating and even melt fuse links.
Switching transient analyses are commonly employed to evaluate:
- The effect of switching of vacuum circuit breakers that supply power transformers
- Power factor correction capacitor switching issues
- Transient recovery voltages produced when a circuit breaker clears a fault
Results are presented in an easy-to-understand format. Recommendations are provided to mitigate the effect of transients.
- Determines stresses that system components are exposed to
- Identifies alternatives to reduce system stresses, which may include: » Alternative switching schemes » Addition of components » Changes in power system configuration
A reliability analysis quantifies the probability that a system or component will operate as intended. Without performing this analysis, the task of evaluating alternative systems and components is left to the engineer’s intuition. Reliability studies are typically performed for mission-critical power systems such as data centers and Critical Operations Power Systems, as defined in the National Electrical Code®. However, the principles of a reliability analysis can be applied to any power system in order to optimize the selection and arrangement of the power distribution components. Reliability indices are presented in an easy-to-understand format. Discussions are provided on the potential failure modes of the system.
- Provides an understanding of the relative effectiveness of different power distribution schemes and/or component selections » Offers recommendations to improve reliability
- Creates indices for cost/benefit analysis at the design stage
- Identifies potential modes of failure in an existing power distribution system
Substation Ground Grid Analysis
Metallic components such as structural steel, electrical equipment enclosures, and fencing in an industrial or utility switchyard are directly or indirectly connected to ground. Under normal operating conditions, these components are at the same potential as the surrounding earth. However, during a ground fault, voltage gradients are generated along the substation walking surfaces and between metallic components and the earth. The grounding grid analysis shows the existing design and the modifications being recommended. The study results graphically demonstrate the final touch and step potentials in the switchyard.
- Optimizes grid geometry
- Evaluates high-risk areas of the switchyard » Identifies opportunities for risk mitigation
A stability analysis evaluates various power system scenarios corresponding to switching actions or the initiation of a fault. Stability studies are typically applied to facilities that utilize large generators. The goal is to determine conditions for prolonged voltage fluctuations that would cause the system to become unstable. By changing the parameters of the system and running alternate scenarios, opportunities are evaluated to correct the deficiency. The final report provides a description of the conditions that cause the power system’s instability as well as alternative equipment and system arrangements.
- Minimizes downtime by providing an understanding of the system’s response to abnormal conditions
- Allows better preparation for the development of a contingency plan » Comparing alternative scenarios enables mitigation of stability issues through improved system protection or switching