Electrical Power Systems Consulting Firm

Arc Flash Study

The arc flash analysis follows the latest version of NFPA 70E “Electrical Safety in the Workplace”, and uses IEEE Std.1584-2018 “IEEE Guide for Performing Arc-Flash Hazard Calculations”. IEEE Standard 1584 provides the equations and methodology to accurately calculate potential levels of incident energy. The flash protection boundary, as defined in NFPA 70E, is the distance at which the incident energy equals 1.2 cal/cm2. The arc flash protection boundary, of which qualified and non-qualified workers should adhere to, helps to prevent personal injury due to the arc flash. As defined by IEEE 1584-2018, the arc flash, or incident energy analysis, is carried throughout all 480V equipment with limitations to equipment utilizing 240V and below. As per IEEE 1584-2018, “Sustainable arcs are possible but less likely in 3-phase systems operating at 240V nominal or less with an available short-circuit current less than 2000A.” This is a significant change to the 125kVA transformer cut-off in the previous 2002 version of 1584.

Short Circuit Study

The short-circuit analysis evaluates the adequacy of the facility’s electrical equipment to withstand and/or to interrupt the calculated maximum available short-circuit current at its electrically-connected location. Short circuit calculations are performed in accordance with IEEE 141 (Red Book) and IEEE 399 (Brown Book).

Overcurrent Protective Device Coordination Study

The overcurrent device time-current coordination analysis develops suggested device trip settings and, where appropriate, proper ampere ratings for the electrical power system protective devices to achieve desired system protection and electrical service continuity goals. Coordination analysis is performed in accordance with IEEE 242 (Buff Book) and IEEE 399 (Brown Book).

Load Flow / Voltage Drop Study

The load flow study utilizes the system computer model to accurately depict steady-state operation. Engineering software utilizes an iterative approach to solving the load flow problem, calculating the power flow across each branch, and voltages at each bus (node). Results of the load flow study include a tabulated form of branch real and reactive power flows and consequent current flow, bus voltage magnitudes and phase angles, power factor at each bus, and system losses. This information is used to identify overloaded cable runs and/or transformers, select optimal transformer sizes, tap points, as well as select optimal size, placement and control of power factor correction capacitors.

FIELD MEASUREMENTS / LOAD SURVEY

System load measurements are recorded in the field by NFPA 70E-Qualified technicians utilizing portable power meters, or fixed mounted meters within the distribution equipment. These actual power quantities are measured at strategic points along the distribution system. Measured quantities of current (I), voltage (V), and the angle between V and I, which is power factor (pf), are used to calculate real (kW), reactive (kVAR), and apparent (kVA) power quantities. The data is summarized by our licensed engineer in a written report, and all raw data, calculations, charts, tables, and graphs are provided. The report also highlights any power system anomalies to ensure optimum performance.

MOTOR STARTING STUDY

The motor starting study considers the system effects during the starting of a motor. The motor starting method, whether across-the-line, soft start, variable frequency, capacitive, or a simple two step starting contactor has a significant effect on the behavior of the system under starting condition due to large initial current draw. Bus voltages and branch currents are evaluated against standard limits and component ratings.

POWER QUALITY / HARMONIC STUDY

The Harmonic Analysis Study calculates system impedances for the fundamental and harmonic frequencies considering non-linear loads such as variable frequency drives, UPS’s, and switched-mode power supplies. SKM HiWave software is used to to perform a Fourier Analysis to determine magnitudes of harmonic voltage and current. Results of the Harmonic Analysis Study include a tabulated summary of calculated voltage and current harmonic magnitudes for each electrical node of the distribution system under study. Recommendations are developed upon calculated results and include comparisons to IEEE 519 harmonic limits, employment of harmonic filtering, and/or concerns of overheating of inductive and/or capacitive components with recommended solutions.

GENERAL CONSULTING

Carrying decades of power systems field and engineering experience, AB Engineering provides technical expertise on an assortment of technical power systems topics. Whether your question as simple as an opinion on a low voltage breaker to coordinate with downstream, a method to lower system impact during motor starting, or a unique solution to reduce incident energy at a particular piece of equipment, we have your ear, and are readied with your sound, weathered solution.

FIELD DATA COLLECTION

AB Engineering performs site surveys to gather pertinent component data in support of an arc flash study for each individual site. Component data includes nameplates of transformers, motors, generators, switchboards, panelboards, switches, circuit breakers, and fuses, as well as cable sizes and lengths of runs between electrical points. Equipment covers will be removed where needed to gather this information. Data is collected by a NFPA 70E-qualified technician with requested support by customer personnel for location and access of equipment.

Technical Training

AB Engineering offers technical training for your technical staff in the following popular topics:

• Arc Flash
• Protection / Coordination
• Short Circuit Analysis
• Power Quality
• Harmonic Analysis