2 Executive Summary.pdf

Executive Summary

Executive Summary Page 1

This section intends to give a brief synopsis of the study's observations, findings, and recommendations to improve the safety and reliability of the different electrical systems.

Findings and Recommendations

The Veterans Affairs Medical Center receives its power from the local Xcel Energy Company via two overhead 13.2 kV lines. This power is routed to the main Automatic Throw Over (ATO) cabinet and then distributed from the adjacent medium voltage distribution switchgear to the hospital campus with primary underground cables.

Two National Electric Code (NEC) tap violations were identified. Per the NEC a tap is where a smaller ampacity conductor is connected to larger ampacity conductors, and specific rules apply. In each case, it is recommended that a properly sized overcurrent protective device be added in line with the smaller conductor at the tap point

Building 1 South

Distribution Board EMCR feeds Panel 1CR3A with a 3/0 AWG (200A) feeder protected with a 200A breaker. Panel 1CR5A1 # 4 AWG (85A) feeder taps Panel 1CR3A feeder without an overcurrent protective device sized for the step down in conductor ampacity. The National Electrical Code requires changes in wire sizes to meet specific conditions, one of which is to provide overcurrent protection sized for the smaller wire's capacity.

Building 8

Switchboard 8-MDP feeds Panel 6L1 with a 350 kcmil feeder protected with a 350A breaker.

Panel 6L2-1 3/0 AWG (200A) feeder taps Panel 6L1 feeder without an overcurrent protective device sized for the step down in conductor ampacity. The National Electrical Code requires changes in wire sizes to meet specific conditions, one of which is to provide overcurrent protection sized for the smaller wire's capacity.

Other section of this report may include observations and recommendations.

System Data

Available system record drawings were limited or missing, and extensive effort was made on-site by the VA's personnel and this Contractor to collect system data. Overall, this generated good results, and most of the information required for this study/report was collected. Some information was not obtained, either due to missing or damaged equipment labels or the inability to trace a few circuits.

Operating personnel are encouraged to review the report's data for completeness and accuracy. Any discrepancies need to be recorded and preserved for future use. This document should be viewed as a living document and actively maintained.

Executive Summary Page 2

Absence of record drawings hindered data collection and required much of the cable data, such as type of insulation and cable diameters, to be documented based on observation when the cable's markings were not visible or legible. All cable distances are approximated based on orthogonal cable runs and distances estimated by horizontal and vertical distances observed from the source of feed to the final termination.

Overall, this is an acceptable method in that cable distances and diameters have a small impact on the overall outcome if reasonably close.

Short Circuit Analysis

A short circuit analysis study of the building's electrical system was conducted. The majority of the electrical equipment was found to be adequately rated for their service. However, there are several locations where the available fault current exceeds the equipment's rating. This is both a reliability and safety issue.

From a reliability perspective, catastrophic equipment failures can occur from the simple act of opening a breaker to clear a fault; and it escalates to an internal fault in the equipment. The duration of such an outage will be greatly extended due to the escalation of the fault. Predictability of fault containment cannot be assured. In these situations, personnel may be at greater risk of arc flash when in the vicinity of this equipment. This report recommends replacing equipment that is not within its rating for both safety and reliability reasons. This equipment is identified in the Equipment Duty Report found in each system, Sections 1 thru 6.

A condensed tabulation of equipment either in Violation or noted as Warning is included in Section 3.

Coordination Study

The coordination portion of the study addresses how multiple overcurrent protective devices (OCPD) respond to a fault condition. The ultimate desire is to have a single OCPD open and be the one closest to the fault. This will result in the minimum disruption to the system by limiting the outage to the smallest area. The majority of OCPD are molded case breakers with an instantaneous trip. Instantaneous trip units typically do not coordinate, which often occurs throughout the campus. This is particularly problematic on the emergency systems. These systems are by code to be selectively coordinated which typically is not achieved when instantaneous trip units are present. At the branch panel levels with molded case breakers selective coordination is not achieved.

Arc Flash Study

The arc flash study found a fair amount of equipment in the extreme danger range or at a higher level of arc blast. No amount of Person Protective Equipment (PPE) can protect personnel from these conditions.

The majority of the locations were identified where appropriate PPE can be used to perform work on energized equipment. As part of the study, labels were prepared and installed on each piece of equipment to post the level of exposure to which personnel may be exposed.