Power Coordination & ARC Flash Studies
The purpose of these surveys is to view electrical equipment in order to determine that abnormal conditions do not exist at existing load levels as evidenced by localized heating.
Thermographic surveys should be performed during periods of maximum possible loading but not less than forty percent of rated load of the electrical equipment being inspected. The thermographic survey will be made using a scientific grade HD infrared camera. This device converts infrared radiation (heat) into a visible image and visually contrasts the heat levels of the junctions to similar junctions and background heat. The ultrasonic survey is accomplished using a device that compares soundwaves of the operating equipment to that of the background noise and determines if there is a “partial discharge” present within the system. This test is performed with the equipment energized and loaded with no need to remove panel covers. All discrepancies will be noted as to location, description and recommended solution in a written report.
Repairs & Preventative Maintenance
A. Murphy Inc. IBEW Electricians will review and perform all necessary deficiencies discovered in the IR Scanning Report. More than two-thirds of electrical system failures can be prevented by a routine preventive maintenance program. The failure rate of electrical equipment is three times higher for components that are not part of a scheduled preventive maintenance program as compared with those that are. The A Murphy Project Team can develop an EPM Program that includes IR Scanning, Distribution evaluation and breaker testing to minimize the potential of any catastrophic failures.
1. Short Circuit Study
The short circuit study will be completed, including a calculation of the three-phase and single-phase fault currents available at the various switchboards and downstream panelboards. A computer model will be created for the normal operating configuration of the renovated facility, to determine the available fault levels at the various switchboards, panelboards, and transformers. Large motor loads (greater than 50 hp) will be considered for fault current contributions, for those motors which information is provided for.
Maximum short circuit currents will be provided for each of the devices shown on the one line diagrams. These short current circuits will be compared to the interrupting devices of each panelboard, and recommendations will be provided for those panels or devices that do not have a sufficient interrupting rating.
2. Protective Device Coordination Study
The protective device coordination study will determine the appropriate interrupting device settings to maximize the protection of electrical equipment from faults. The coordination studies will attempt to provide device settings that minimize nuisance interruptions, by selectively having the interrupting device closest to the fault operate in the shortest amount of time. We will indicate in our report(s) any problems with the coordination of the proposed devices, and make recommendations for changes to device settings, and fuse sizes. The scope of the studies will include the largest protective device in each of the downstream panelboards from the main low voltage switchboards and panelboards as indicated on the riser diagrams.
3. Arc Flash Hazard Evaluation Study
A detailed Arc Flash Evaluation is used to determine the maximum available incident energy that could result from a failure of, or contact with electrical equipment. The calculated available energy of an electrical arc will determine the required class of Personal Protective Equipment (PPE) that must be worn, in accordance with the latest editions of the NEC §110, NFPA 70E and IEEE Std. 1584. The available incident energy is calculated at each major piece of electrical equipment based on bolted short circuit current values and clearing times of upstream protective devices. The Arc Flash Evaluation will include a report summarizing the equipment considered, calculation method used, and assumptions consistent with industry guidelines. The report will include results of the Evaluation in tabular form, listing maximum incident energy, safe approach distances and PPE recommendations.
Arc Flash Hazard Labels (self-adhesive) will be provided & installed on the electrical equipment, consistent with NEC 110.16 labeling requirements. A detailed Study Report will be provided containing the results of the studies listed above and proposed device settings. The physical Re-Setting of any Devices in the field will be Determined in the Report and scheduled and Priced accordingly under a separate project.
The study/report will be performed and sealed by a Registered Professional Engineer, who has experience in high and low voltage systems, relaying, protection, and construction practices.