Amendment 0002_2019 Coordination and Arc Flash Study.pdf

Introduction

The intent of this report is to describe the results of the power quality study for the existing electrical system at the Mann-Grandstaff Veterans Affairs Medical Center.

Project Scope

The study’s scope is the following:

Provide a one-line diagram of studied electrical system.

Verify the interrupting ratings and the bracing of the electrical equipment is adequate for the exposure to fault currents Conduct an arc flash analysis study and provide equipment arc flash labels for field installation.

Review and comment on observed field conditions where maintenance and code variation may need attention.

Report Organization

Data Collection and Assimilation

The data collection and assimilation is comprised of data obtained others, published information, through onsite discovery, equipment nameplate data, manufacturer rating, or other means. The site data was collected using personnel from SDV Services, Inc.

The collected system data is compiled and used to create an up-to-date one-line riser diagram of the systems facilities, Power System Studies

The power system studies are performed to– determine magnitude of short circuit currents throughout the electrical system; establish the relationship of protective devices as related to device coordination; and establish arc flash incident energy levels and personnel exposure to arc flash limits at equipment. Easy Power Version 10.2 is used to computer model the electrical system and is one the industry’s most respected software products for these applications. The program converts the electrical systems physical properties, such as wire sizes and lengths; transformer capacities; motor horsepower; etc. into their electrical equivalents. Then the various electrical computations are compiled based on the type of analysis required.

System data and computer generated data Organization

System data and computer generated data is divided into multiple sections and organized by building and source transformer under separate tabs following the reports narrative sections. The narrative section has discussions related to the report findings.

Executive Summary

Executive Summary Page 1

The intent of this section is 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

System Data

Available system record drawings were limited and extensive effort was made on site by both the VA’s personnel and this Contractor to collect system data. Overall, this generated good results and practically all 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. When data could not be confirmed conservative assumption were made to make the model whole.

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.

The existing one‐line diagrams proved useful in establishing overall understanding of the electrical systems configuration but were incomplete or did not capture changes to the system over time. The available one‐lines did not provide overall cable data which required field verification of insulation type and cable diameters based on observation of cables markings when legible. All cable distances are approximated based on cable runs being orthogonal and distances being estimated by both 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 conductor sizes have a small impact on overall outcome, if reasonably approximated.

Short Circuit Analysis

A short circuit analysis study of the building’s electrical system was conducted. Multiple incidences have been identified where breakers are in locations with available fault currents exceeding their ratings. It is recommended that corrective action be taken, which mainly requires their replacement with a breaker of a higher rating. The equipment duty tabulations are under the individual report sections listing the breaker’s AIC rating with the corresponding system fault current.

A summary listing of each of the Equipment Duty reports is provided at the end of the section titled “Short

Circuit Analysis Study” in Appendix A.

Coordination Study

A coordination study is used to evaluate the relationship between overcurrent protective devices’ opening times. It is desired to have the overcurrent protective device closest to a system fault or overload to open before any upstream devices open. When the relationship between overcurrent devices is such that the device closest to the fault will always open first, it is categorized as being selectively coordinated. Based

Executive Summary Page 2 on the National Electrical Code, both the life safety and critical power circuits are required to be selectively coordinated.

Neither of these systems meets the requirements of a selectively coordinated system. It is feasible for a faulted circuit deep within the system to cause the main breaker to open, leaving the entire electrical system de‐energized. This condition exists whether on normal or emergency power.

A natural course for corrective action is not evident due to the need for extensive revisions to the electrical system.

The electrical distribution system mainly consists of molded case circuit breakers that, by design, have instantaneous trip elements. In order to obtain coordination between instantaneous trip elements, significant impedance is required between devices, such as a transformer. The hospital’s electrical distribution system’s design does not provide this impedance, and thus the majority of circuits do not achieve selective coordination. Due to the extensive use of molded case breakers throughout the hospital, it is not economically feasible to alleviate these occurrences. Operating personnel need to be aware that multiple breakers can open for a system fault, or the breaker that does open may not be the one nearest to the fault.

Arc Flash Study

The Arc flash study found a few locations 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 safely work on energized equipment. A notable exception is the service entrances fed from medium voltage transformers. These transformers do not provide secondary overcurrent protection for the downstream service entrances, and thus a fault condition (highest fault currents are occurring closet to the transformer) can be sustained for an indeterminate amount of time. This is a common situation without any remedies.

As part of the study, labels were prepared and installed on each piece of equipment to post the level of exposure to personnel.

Medium Voltage Distribution

It is the intent of the National Electrical Code for the Standby Power Systems such as Life Safety, Critical

Power, Equipment and Legally Required systems to be treated in a manner that insures they are available and not influenced by outages from the normal source of feed. This seems to be in question, particularly at the Medium Voltage level. At the main MV switchboard, the utility and emergency power sources share a common bus. From this bus both the normal power and emergency power feeders are sourced.

A system fault on this bus will leave the entire facility without power. Depending on the severity of a failure at this location, it could take days before power could be restored.

Executive Summary Page 3

In a similar manner, both the normal and emergency power feeders are routed in the same manholes. If care has not been taken to provide both separation and/or protective fire wrap on these cables, it is possible that a fault in a manhole could damage adjacent cable(s), thus removing them from service. With the medium voltage distribution system being a loop feed, it is possible to restore service to the affected area(s) within hours. This, however, exposes the hospital to having a total localized outage. If designed and installed per the intent of the NEC, an outage is less likely to happen.

The actual way cables have been installed in the manholes is unknown. It is recommended that existing conditions be evaluated.

Short Circuit Analysis Study

Short Circuit Analysis Study Page 1

A Short Circuit Analysis Study is typically comprised of three parts – Findings and Recommendations, Short Circuit Data and Short Circuit Calculations. The Findings and Recommendations are the culmination of the engineer’s observations and assessment of present conditions. These findings are generally related to equipment being exposed to conditions where available fault currents exceed the equipment’s ratings.

The section on Short Circuit Data is used to report the studied system’s actual system configuration (generally by one-line diagrams) and a detailed listing of the component pieces comprising the system (e.g., cables, transformer, motors, breakers, etc.). The Short Circuit Calculation section contains the computer generated analysis of the system(s). Multiple scenarios are often generated to analyze different operating conditions and/or possible alternate configurations for future considerations.

A Short Circuit Study forms the foundation for the overall power system analysis. To conduct a short circuit study the electrical system(s) is modeled capturing the system overall configurations. System components such as transformers, switchgear, panelboards, cable data, motors, etc. are input into the software in a manner to interconnect the individual components as they occur in the real world. The completed model is used to simulate 3-phase faults at each piece of equipment. In this section the resultant fault currents are compared with the associated equipment’s withstand rating (ability to withstand the mechanical forces produced by fault currents). An Equipment Duty Report is generated by the Easy Power that tabulates a listing of equipment and their corresponding exposure to fault currents and as a percent the equipment’s rating related to available fault current.

The fault currents are required as input data for both the coordination and arc flash studies.

Findings and Recommendations

Multiple incidences have been identified where breakers are in locations with available fault currents exceed their ratings. It is recommended that corrective action be taken, which mainly requires their replacement with a breaker of a higher rating. In some incidences replacement of the whole panel may be required.

The equipment duty tabulations under the individual report sections list each breaker’s AIC rating with the corresponding system fault current. A summary listing of each of these reports is provided at the end of this section in Appendix A.

Short Circuit Data

Before an electrical system can be analyzed and Short Circuit Calculations performed, system data must be collected and modeled to represent the studied system. Collecting system data is generally an exercise of reviewing existing documents, particularly existing one line diagrams, and the collection of site data.

Collection of site data typically requires a site investigation to record equipment manufacturer data and assesses actual field conditions. Collected data is generally a mixture of electrical and non-electrical (wire gauge, length, Model numbers) properties and their interconnection within the electrical system. An electrical system’s physical components include such items as listed below and their physical properties as indicated:

Short Circuit Analysis Study Page 2

Utility Data – System Nominal Voltage, Available Fault Current and X/R ratio and/or Symmetrical Component Values.

Cables – Voltage and Type Insulation, Length (in feet), Wire gauge, Copper or Aluminum, Type (single conductor, multiple conductor, in conduit (steel or aluminum), etc.).

Cable or Bus Duct –Voltage, Ampacities, Length, and related impedance data.

Transformers – Primary and Secondary Voltage, kVA rating, Percent Impedance, Winding configuration.

Switchgear and Protective Devices – Voltage Rating, Ampacities, AIC ratings.

Generators – Base kVA, Voltage Rating, X’’dv Sub transient reactance.

Motors – Base Voltage, Horsepower, Type (induction, synchronous, etc.), RPM.

Current Limiting Reactors – Voltage, Ampacities, kVA rating, winding configuration and related impedance data.

While physical properties are familiar and readily identifiable to an individual, they are not suitable for a digital computer to perform short circuit calculations. This data has to be converted into its electrical properties – impedance (resistive and reactance values). The Short Circuit Program contains sub programs to convert the individual electrical components to their equivalent electrical properties. Some of these conversions are direct mathematical conversions yielding precise impedances. Other conversions use empirical data from the software’s equipment library to establish typical impedance values. This is a standard practice in the industry and is necessitated because manufacturer impedance data is not published or available.

The one line diagram is used both to establish interconnections and arrangement of the electrical system’s components forming the system and for presentation purposes. The collected system’s components are input into the electrical analysis software to create a one line diagram establishing their relationship with respect to each other while displaying their physical properties (cable, motor, etc.). The resultant one line diagram is a visual tool for presentation and for verification of data input accuracy. The software in the background translates the one line into an impedance diagram for matrix computational purposes.

A system bus is established in the impedance diagram for every interconnection of two or more system components. A bus is also referred to as a node and is a point in the electrical system model for the termination of system components. A system component has two or more termination points with the exception of voltage sources such as utilities, generators and motors. For example, a cable connecting a switchgear breaker to a motor is terminated on both ends to a bus. The same cable without the motor is still terminated on both ends to the same buses.

Short Circuit Calculation and Theory

Short Circuit Calculations are used to simulate fault conditions and the resulting maximum current flow that the system devices and interconnections would be subject to in the event of a system fault. The computer short circuit program calculates fault currents for each bus within the system. The resulting

Short Circuit Analysis Study Page 3 calculations are used to evaluate adequacy of installed equipment’s bracing; interrupting capabilities of switches, breakers and fuses; and to establish protective device coordination settings.

Short Circuit calculations use the impedance diagram established from the one line diagram to perform digital matrix calculations to generate system fault currents. Fault currents are determined for each bus by computer simulation of a fault at each bus. Depending on the study’s objectives, different fault types can be simulated such as three phase faults (three phases effectively bolted together), phase to ground, etc.

The fault calculations were performed using Easy Power Version 8.0.2 software by ESA. This program is compliant with standard established by ANSI/IEEE Standards C37.13.1 “IEEE Standard for Definite Purpose Switching Devices for Use in Metal-Enclosed Low-Voltage”, C37.01 “IEEE application guide for AC high-voltage circuit breakers rated on a symmetrical current basis”, and C37.5 “IEEE Guide for Calculation of Fault Currents for Application of AC High-Voltage Circuit Breakers Rated on a Total Current Basis”, NEMA, and NEC.

The program offers four different fault types for short circuit analysis. Three phase is generally used to determine the highest available currents for equipment duty comparison and establishing relay settings.

Line to Ground is generally used to determine ground fault values for setting ground relays. Double Line to Ground and Line to Line are generally used for specialized relaying applications or system trouble shooting. This study included Three Phase and Line to Ground.

Short circuit calculations are based on ANSI Standards. The ANSI Standard method used a separate R network for the interrupting duty (2-5 cycles) network to determine a conservative Z/R ratio. This ratio is then used as the Thevenin equivalent fault point X/R ratio for determining the appropriate breaker contact parting time multipliers and NACD ratios. NACD (No AC Decrement) ratios are calculated with consideration of generator Local and Remote contributions as outlined in ANSI Std. C37.010 and Interpretation of New American National Standards For Power Circuit Breaker Applications by Walter C.

Huening Jr. IEEE Oct 1969. Current and voltage calculations are based on a complex (R+jX) network reduction. Both the momentary (1/2 Cycle) and the 30 cycle calculations use a complex network reduction for all voltages, current, and X/R ratio calculations.

ULow Voltage Analysis Low voltage power circuit breakers are applied in accordance with ANSI Std.

C37.13. Current manufactured breakers are rated on a symmetrical interrupting basis. Pre-1957 low breakers had an average asymmetrical rating and were required to be at least 1.25 times the ½ cycle symmetrical short circuit duty, For momentary duty (1/2 cycle) faults, the positive sequence impedance is assumed equal to the negative sequence impedance. X/R ratios are derived from the complex network.

UInterrupting Analysis The values calculated are to be compared with the interrupting duties for high voltage (above 1 kV) circuit breakers. Duty faults are modeled using multipliers to modify rotating machine sub transient impedances (positive sequence) as outlined in ANSI Std C37.010. Negative sequence impedances are modeled using the rotating machine subs transient impedances with no multipliers. A separate “R” (resistance) network is formed for calculation of the fault point X/R ratio. The X/R ratio used for the

Short Circuit Analysis Study Page 4 calculation of the interrupting duty multipliers is then found from the relationship Z/R. This method fully complies with the ANSI Standard.

For 30 cycle faults, all motor contributions have decayed to zero, and a modified generator impedance of

1.5 X”dv is used. This provides conservative results which are typically higher than most dynamic studies indicate.

Symmetrical Fault currents are AC currents without any DC component. Low Voltage equipment bracing and interrupting duties are evaluated based on symmetrical current.

Asymmetrical Fault currents have both an AC and DC component. The asymmetrical value is the maximum possible asymmetrical value in any phase. Asymmetrical currents are based on the following equation:

Iasym = I sym [ 1 + 2e{-4πτ / (X/R)}]1/2 τ = 0.49 – 0.1 e{-(X/R)/3}

For interrupting duty currents the asymmetrical value is based on the fault point X/R ratio, the No AC Decay (NACD) ratio, the contact parting time of the breaker, and whether the breaker is rated on a Total or Symmetrical basis. The NACD ratio consists of two factors dependent upon whether generation is Local or Remote. The basis of whether a generation is local or remote is based on ANSI standards. A utility source is almost always Remote because a system fault has no impact on the utility fault contribution.

ULow Voltage (LV) DutiesU are based on momentary or ½ cycle faults. Per ANSI terminology, the term “interrupting” as used for low voltage equipment applies to momentary or ½ cycle faults. This is because low voltage equipment typically interrupts within ½ cycle of fault inception. The interrupting currents are calculated by adjusting the symmetrical current if the equipment test X/R is less than the fault point X/R ratio. The following equation is used to determine the currents:

Iadjsym = I sym [ 1 + e{-2πτ / (X/Rsys)}]/ [ 1 + e{-2πτ / (X/Rtest)}]

X/Rtest = TAN[ARCCOS(Tested PF)]

High Voltage (HV) Breaker Duties are based on adjusted symmetrical currents. The interrupting currents are calculated by adjusting the symmetrical currents with a multiplying factor. For breakers the multiplying factor is based on the fault point X/R ratio, the No AC Decay (NACD) ratio, and the contact parting time of the breaker, and whether the breaker is rated on a Total or Symmetrical basis. The NACD ratio consists of two factors that are dependent upon whether generation is Local or Remote. These calculations are based on ANSI standards and are too detailed for inclusion in this report.

Short Circuit Analysis Study Page 5

Fuse Duties (HV & LV) are based on adjusted symmetrical currents. Fuse multiplying factors are based on the fault point X/R ratio and the fuse test X/R ratio. The interrupting currents are calculated by adjusting the symmetrical current if the equipment test X/R is less than the fault point X/R ratio. The following equation is used to determine the currents:

Iadjsym = I sym [ 1 + 2e{-4πτ / (X/Rsys)}]1/2/ [ 1 + 2e{-4πτ / (X/Rtest)}]1/2

Standard test X/R ratios are 5, 8, 12, and 15 for distribution and power fuses.

EQUIPMENT DUTY REPORT

Equipment Duty Report is a listing of equipment with their AIC withstands rating and the exposure of this equipment at its installed location.

Building 1 ATS 1 T22, 23

Panel BLS‐3 is reported to be exposed to fault currents greater than its rating by 6.2%. This breaker should be replaced by a similar breaker such as a Square D QD breaker.

Building 1 ATS 2 T22, 23

Panel BCB is reported to have four breakers having ratings within 4.2% of their AIC rating and is listed as a warning. The margin of safety is minimal and with variations in breaker overall condition and/or age could increase its potential for failure should they experience a full magnitude fault. Considerations should be given to replacing these breakers with a breaker of a higher AIC rating.

Building 1 ATS 3 T22, 23

Panel 4EQ‐1 is reported to have its main breaker to be exposed to fault currents greater than its rating by 24.2%. It is recommended this breaker be replaced with a compatible breaker having an AIC rating of at least 22kA.

Building 1 ATS 4 T22, 23

All equipment is reported to be within its rating. No action is required.

Building 1 ATS 5 T22, 23

UPS‐1 IT is reported to have one breaker having ratings within 9.3% of their AIC rating and is listed as a warning.

Building 1 ATS 6 T22, 23

All equipment is reported to be within its rating. No action is required.

Bldg 1 Special Care T19

Panel BN‐1 is reported to be exposed to fault currents greater than its rating by 11.7%. This breaker should be replaced by a similar breaker with a compatible breaker having an AIC rating of at least 22kA.

Building 1 Swbr A,B T18

Panels 2N‐1 and 2N‐4 are reported to be exposed to fault currents greater than their ratings. This breaker or panels should be replaced with breakers having an AIC rating of at least 22kA for Panel 2N‐4 and 65kA for Panel 2N‐1.

Building 2 –T10

All equipment is reported to be within its rating. No action is required.

Building 2,3 T7,9

Multiple panels and breakers are reported to be exposed to fault currents at or above their ratings.

Panel 3P3 is within 2.7% of its rating and listed as a warning. Panels 1L, 1P, 2P Laundry, 3P, and MDP are significantly exposed fault current beyond their rating and corrective action need to be addressed.

Building 4,5,6,6A T12

All equipment is reported to be within its rating. No action is required.

Building 7 T13

All equipment is reported to be within its rating. No action is required.

Building 12 T17

All equipment is reported to be within its rating. No action is required.

Building 14 T8

All equipment is reported to be within its rating. No action is required.

Building 27 T15

All equipment is reported to be within its rating. No action is required.

Building 27, 40 T21

Multiple panels and breakers are reported to be exposed to fault currents at or above their ratings.

Panel L_A is within 5.6% of its rating; Panel P1A is within 7.2% of its rating and Panel M is within 0.4% of its rating. Panels LL, P_A and PNL_TEMP are significantly exposed to fault current beyond their rating and corrective action need to be addressed.

Building 30, 33 T16

Panel LP1‐1 has a branch breaker that its AIC rating could not be identified. For reporting reasons the lowest possible AIC rating is reported. Using this rating this breaker is exposed to fault currents that exceed its rating. Either the breakers AIC rating needs to be identified or this breaker needs to be replaced with one having the proper AIC rating.

Building 32 T14

All equipment is reported to be within its rating. No action is required.

Building 38 T5

Building 40 T20

Building 41 T16

All equipment is reported to be within its rating. No action is required.

Medium Voltage

Equipment Duty Schedule

Equipment Duty Schedule Page 1

Each section has an Equipment Duty report listing the equipment within that section and their exposer to fault currents. Each piece of equipment is evaluated based on its rating and its exposure to fault current.

The following is provides to aid in reading and understanding the information provided in the Equipment Duty Schedules.

SECTION HEADER

1st Line – Identifies Easy Power Software and Version #, Date of last entry or Creation date, and Path and electronic file name.

The right side of the page includes the current page number and the total number of pages included in this schedule.

2nd Line – Software Creator ESA, Inc 3rd Line – Comments Specific to this Report 4th Line – Identifies Fault Type and Per Unit Voltage

TABLE HEADERS

BUS – Includes Bus name and Base kV

Bus name uses the same naming convention as the one-line and short circuit analysis report which identifies equipment location within the system.

Base kV lists the bus and associate equipment operating voltage and in turn establishes the Standards governing equipment ratings.

EQUIPMENT – Includes entries for ID, manufacturer, style and test standard.

Equipment ID identifies the equipment being evaluated.

The term “Main” indicates the equipment has a main breaker.

The term “Lowest” indicates equipment evaluated on bus bracing only.

Equipment Manufacturer: Name of equipment manufacturer

Equipment Style: Lists equipment type and/or model.

RATINGS – Includes entries for ½ cycle kA, int kA, int cycles.

½ Cycle kA: available ½ cycle momentary fault current in kilo amps at this location.

Int kA: are the available interrupting fault current in kilo amps at this location.

Int Cycles: indicates the number of cycles after fault inception the interrupting fault current are calculated.

Equipment Duty Schedule Page 2

DUTIES – Includes ½ cycle kA, ½ cycle percent, int kA, int Percent.

½ Cycle kA: Lists the equipment’s momentary rating in kilo amps.

½ Cycle Percent: Lists in percent (above or below (minus)) the equipment’s rating versus exposure to available momentary fault currents.

Int kA: Lists the equipment’s interrupting rating in kilo amps.

Int Percent: Lists in percent (above or below (minus)) the equipment’s rating versus exposure to available interrupting fault currents.

COMMENTS:

“Violation” indicates a piece of equipment is exposed to fault currents which exceeds the equipment’s rating.

“Warning” indicates a piece of equipment rating is below but within 5% of the fault current rating based on calculation. Precision of the short circuit calculations could be viewed as not exact but with a tolerance of approximately +/- 5%. Therefore, equipment designated with a “Warning” could be exposed to its fully rating.

Low Voltage Momentary Report

Low Voltage Momentary Report Page 1

Each section has a Short Circuit report listing the system buses within that section and the available fault current at these locations. The following is provides to aid in interpreting and understanding the information provided in the Low Voltage Momentary Report.

1st Line – Identifies Easy Power Software and Version #, Date of last entry or Creation date, and Path and electronic file name.

The right side of the page includes the current page number and the total number of pages included in this schedule.

2nd Line – Software Creator ESA, Inc 3rd Line – Comments Specific to this Report

FAULTED BUS – Includes Bus name, Base kV, 3 Phase and Voltage per unit value Bus name: uses the same naming convention as the one‐line and short circuit analysis report which identifies faulted bus location within the system.

Base kV: lists the bus and associate operating voltage.

3 Phase: identifies the fault type as being a 3 phase bolted fault.

Vpu:‐voltage per unit expresses the system voltage as fractions of the base unit.

This simplifies calculations where different voltages are present in a system.

FAULT DUTIES – Includes entries for E/Z (kA), MVA, Degree, X/R, R1 (pu), X1 (pu), R0 (pu), and X0 (pu).

E/Z (kA): The Thevenin Equivalent (symmetrical) fault current in kilo amps at this location.

MVA: The Thevenin Equivalent MVA fault value at this location.

Degree: The voltage to current phase angle. This is used to determining the power factor (P.F.).

X/R: The ratio of reactance and effective resistance of the effective system fault impedance at this location.

R1 (pu): Positive sequence resistance from the point of the fault.

X1 (pu): Positive sequence inductive reactance from the point of the fault.

R0 (pu): Zero sequence resistance from the point of the fault.

X0 (pu): Zero sequence inductive reactance from the point of the fault.

Low Voltage Momentary Report Page 2

ASYM CURRENT – Includes entries for kA (1.6*Isym) and kA (based on X/R).

kA (1.6*Isym): Maximum asymmetrical current based on a factor of 1.6 times the symmetrical fault current.

kA (based on X/R): Asymmetrical fault current based on the fault impedance X/R ratio.

CONTRIBUTIONS in kA – Includes entries for the “from bus”, “to bus”, kA, Deg, device and Branch.

From Bus: list the adjoining buses directly contributing to the faulted bus.

To Bus: list the faulted buses.

kA: Fault current in kilo Amps contributed by “from bus”.

Deg: The power factor phase angle for contributed fault current.

Device: Indicates the type of contributing source.

Branch: Indicates the name of the adjoining equipment feeder (conductors, cables, busways, etc.)

Definitions:

BWY designates busway in this report.

From: Jerry Parks <jmparks04@windstream.net>

Sent: Friday, October 18, 2019 7:24 AM

To: Roland Weekley

Subject: FW: [EXTERNAL] RE: [External] VA Medical Center - Instantaneous

Currents

Here is the utility data.

Jay

From: Ryan, Kyle P. (SPO) <Kyle.Ryan@va.gov>

Sent: Thursday, October 17, 2019 12:00 PM

To: Jerry Parks <jmparks04@windstream.net>

Cc: McHugh, James B. (SPO) <James.McHugh2@va.gov>; Otto, Keith T. (SPO) <Keith.Otto@va.gov>;

Carrillo, Emilio (SPO) <Emilio.Carrillo@va.gov>; Studebaker, Jon K. (SPO) <Jon.Studebaker@va.gov>

Subject: FW: [EXTERNAL] RE: [External] VA Medical Center - Instantaneous Currents

Jay, Let me know if this isn’t what you’re looking for. See below

Also, your availability for site visit with the electrical engineer.

Thanks, -Kyle

Sent with BlackBerry Work

(www.blackberry.com)

From: Gilrein, Jon <Jon.Gilrein@avistacorp.com>

Date: Thursday, Oct 17, 2019, 8:45 AM

To: Ryan, Kyle P. (SPO) <Kyle.Ryan@va.gov>, Grainger, Eric <Eric.Grainger@avistacorp.com>, Christensen, Jason <Jason.Christensen@avistacorp.com>, Figart, Tim <Tim.Figart@avistacorp.com>

Cc: McHugh, James B. (SPO) <James.McHugh2@va.gov>, Otto, Keith T. (SPO) <Keith.Otto@va.gov>

Subject: [EXTERNAL] RE: [External] VA Medical Center - Instantaneous Currents

Ryan, It was good speaking with you yesterday. Below, please find the updated Fault Values for the VA

Hospital. Note that there is only a slight change from the values John Gross sent you last year. Please let me know if you have any further questions!

Best Regards, Jon Gilrein, P.E.

Regional Operating Engineer www.avistautilities.com

From: Gross, John

Sent: Tuesday, October 8, 2019 4:15 PM

To: Ryan, Kyle P. (SPO) <Kyle.Ryan@va.gov>; Grainger, Eric <Eric.Grainger@avistacorp.com>;

Christensen, Jason <Jason.Christensen@avistacorp.com>; Figart, Tim <Tim.Figart@avistacorp.com>;

Gilrein, Jon <Jon.Gilrein@avistacorp.com>

Cc: McHugh, James B. (SPO) <James.McHugh2@va.gov>; Otto, Keith T. (SPO) <Keith.Otto@va.gov>

Subject: RE: [External] VA Medical Center - Instantaneous Currents

Tim and Jon, Just wanted to pass on that Kyle reached out to me asking if there was any questions on his request for the VA Hospital. I responded with a voicemail letting him know one of you would be the correct ones to provide the information he is looking for.

Thanks, John Gross, Manager System Planning

1411 E Mission Ave MSC-16, Spokane, WA, 99202

P 509.495.4591 | C 509.434.9533 www.myavista.com

From: Ryan, Kyle P. (SPO) [mailto:Kyle.Ryan@va.gov]

Sent: Wednesday, October 2, 2019 8:39 AM

To: Grainger, Eric <Eric.Grainger@avistacorp.com>; Christensen, Jason

<Jason.Christensen@avistacorp.com>; Figart, Tim <Tim.Figart@avistacorp.com>; Gross, John

<John.Gross@avistacorp.com>

Cc: McHugh, James B. (SPO) <James.McHugh2@va.gov>; Otto, Keith T. (SPO) <Keith.Otto@va.gov>

Subject: [External] VA Medical Center - Instantaneous Currents

All, Requesting the instantaneous currents for both of the Spokane VAMC campus services. We are updating our arc flash and overcurrent protective device coordination studies.

The contractor performing the arc flash and overcurrent protective device coordination studies is specifically requesting, “available short circuit MVA, X/R or Amps, X/R and any upstream overcurrent protective relaying or fuse information.”

As a civil engineer I am a bit outside my lane of traffic, but I think we are looking for an update to what

John Gross provided in September 2018:

Thank you for your help, Kyle Ryan, PE

General Engineer, FAC-COR II Mann-Grandstaff VA Medical Center Desk: (509) 434-7406 Mobile: (509) 964-3864

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Protective Device Coordination Study

Protective Device Coordination Study Page 1

Introduction

The electrical power system protective device’s primary function is to detect fault currents and isolate the fault from its source of power by activating appropriate circuit interrupting devices. Protective Device

Coordination Studies strive to establish the setting for or selection of protective devices that achieve best overall system response to an electrical fault. Commonly there are mutually exclusive objectives in this endeavor. Attention must be given to quick isolation of a fault to minimize its escalation and equipment damage while avoiding a system so sensitive that protective devices operate upon normal system disturbances. Other objectives are to isolate the smallest possible area of the electrical system, protect cables and equipment in overload conditions, reduce arc flash levels and achieve “selectivity” between devices.

Selectivity for a protective system can be defined in general terms as: The inter‐related performance of protective devices, whereby a minimum amount of equipment is removed from service when isolating a fault. Stated differently, selectivity requires the closest protective device to the fault to respond to and isolate the fault.

Achieving these objectives is highly desirable. However, it is very common to have to make compromises to meet as many objectives as possible. The term Coordination is sometimes used to describe a reasonable compromise, between the mutually desirable, but competing objectives, of maximum availability and maximum protection. The protective device setting or selection of equipment recommended in this study is based on an exercise of engineering judgment to achieve a balance between these objectives.

Per the National Electrical code Life Safety, Elevators, Equipment and Critical circuits must be selectively coordinated. This is a more stringent condition than just being coordinated. The NEC defines selective coordination as “Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the choice of overcurrent protective devices and their ratings or settings”. An example would be an electrical fault at one elevator would not cause a feeder breaker serving two or more elevators to open, thus taking more than one elevator out of service.

The objective of selecting and setting protective devices is to minimize equipment damage and to isolate only the faulty circuit while obtaining the least amount of disturbance to the remaining system. To achieve the best system performance requires not only good engineering judgment, but also personal knowledge of local operating conditions. The owner is advised to review any recommended changes in light of their system experiences. The recommendations presented in this section are offered as a guide until such time when operating conditions or experiences indicate changes are warranted.

System changes such as changes in a utility’s available fault current, system capacity, system loads and operating procedures may warrant a review of this report’s recommendations.

This study groups the information into two sections – common or generic information and specific study results. This section includes the generic information such as descriptions of study analysis. The study’s specific results and findings are grouped under individual tabs labeled by the studied system’s source transformer. Each section has a summary page capturing that section’s specific findings and observations.

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Findings and Recommendations

The National Electrical Code requires that essential electrical systems (Article 517.26) shall meet the requirements of Article 700 (selective coordination), except as amended by Article 517. Per Article 700.27 and 701.18 Emergency and Legally required standby system(s) and Article 517.26 Equipment and Critical circuits overcurrent devices shall be selectively coordinated with the supply side overcurrent protective devices. Overall these systems do not achieve selective coordination particularly with molded case breakers having instantaneous trip units. It is not possible to make recommendations on how best to correct these conditions without an engineering study. The same is true in estimating the cost to bring the system into compliance.

The non‐essential systems also have areas where selective coordination is not achieved. Again, these are mainly related to molded case breakers having instantaneous trip units.

At the end of this section in Appendix A are comments on the various Time‐Current Curves (TCC) in the individual sections.

Relaying Fundamentals

Basic philosophy in establishing protective device setting or their selection is:

1. The closest upstream protective device to a fault must clear it as quickly as possible to help assure the remaining system is capable of riding through the disturbance and only the fault is removed.

These protective devices are often referred to as “first‐line” devices. High speed devices that provide first‐line protection are customarily instantaneous over‐current devices and differential relays.

2. The next upstream protective device provides a “back‐up” function. To achieve this added protection the device must be able to detect the same fault and operate to clear the fault sometime after the downstream device would normally have cleared the fault. Time‐over‐current protective devices are commonly used in this role.

A backup device can also service as a “first‐line” protective device for an upstream protective zone.

Criteria used in determining time over‐current protective device settings can be based on any or all of the following:

1. The protective device must have a low enough setting to detect fault short circuit current within the protective zone.

2. The protective device must have a high enough setting to avoid nuisance tripping due to transformer magnetizing and/or motor starting inrush currents.

3. The protective device should have the ability to provide flexible settings for circuit full load currents and the ability to coordinate with other protective devices under fault current conditions.

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4. Comply with ANSI/IEEE and NEC standards for the protection of transformers.

Protective Device One‐Line Diagram

A time‐current curve’s (TCC) interpretation is dependent on knowing the physical arrangement of each protective device within the system. The one‐line diagram included with each TCC is provided to illustrate this relationship. The one‐line also provides information on system equipment influencing relay settings such as motors and their starting curves; transformers and associated inrush and protective curves; and breakers having current limiting fuses.

Coordination Curves

Due to the complex relationship between protective devices, competing objectives in obtaining their coordination, and system restraints, the time‐current curve (TCC) evolved as the ideal tool for engineers to perform this work and as an effective means for communication and presentation of the end results.

TCC curves use a standardized log‐log paper to illustrate the time versus current relationship of each protective device and other equipment. This standardization permits different protective devices, by different manufacturers, and of different technologies to be viewed in a common environment.

On a TCC graph time is the “y‐axis” while current is the “x‐axis”. The primary objective in coordinating a system is to have time intervals between protective device curves. In an ideal situation the comparison of two curves would have “daylight” between them. ANSI/IEEE Std‐242 has been published to standardize these time intervals. As an illustration coordinating two inverse time over‐current relays in series a time interval of 0.3 to 0.4 seconds may be prescribed for a five and eight cycle breaker. These time intervals are composed of the following components:

• circuit breaker opening time (5 cycles): 0.08 seconds

• relay over‐travel: 0.10 seconds

• safety factor for CT saturation, setting errors, etc.: 0.22 seconds

When coordinating with fuses, the following components require consideration:

• Fuse total clearing time

• Fuse minimum melting time

The time‐current curves included in this report illustrate the system conditions and the performance that can be obtained from the equipment installed. In most electrical systems having common equipment types by the same manufacturer, patterns develop so that the creation of TCC for every device is not necessary. This is the case for this system. The recommended relay settings have been established from the enclosed TCC’s.

Conductor Damage Curves

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Electrical conductors are restricted in ampacity due to thermal limits. For continuous or long time loads measured in hours or days, the National Electrical Code mandates a conductor rated current carrying capacity. A conductor’s capacity is governed by ambient temperature, allowable temperature rise, geometry, and installation conditions. For insulated conductors the insulation temperature design limits cannot be exceeded or loss of insulation life will result, but not necessarily resulting in instantaneous failure. For bare conductors mechanical strength will be affected if temperature design limits are exceeded. Again mechanical life is lost, but not necessarily resulting in instantaneous failure.

For long time continuous operations conductor’s temperature rise is influenced by the above mentioned parameters. For fault conditions time restraints are so short that conductor environmental conditions do not factor into a conductors temperature rise. The TCC conductor curves are based on calculations assuming the heat generated by fault currents is absorbed by the conductor metal and no heat is transmitted to the conductor’s insulation.

Calibration and Testing of Protective Devices

The final step in a coordination study is to apply the recommendations. Generally, this requires the studied relay to have the new setting applied and tested. Relay testing is a critical step in this process to validate the breaker and relay are calibrated and working correctly.

It is assumed an electrical system will operate predictably and reliably over long periods of time and its breakers and relays will perform as expected. To achieve this routing maintenance is required. It is absolutely imperative that regular calibration and maintenance be conducted at regular intervals as recommended by the equipment manufacturers.

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Appendix A

The following are comments pertaining to the Time‐Current Curves (TCC) provided in the individual report sections.

Building 1 ATS 1 ‐ Time Current Curves

Bldg 1 TCC E ATS1‐1

This TCC represents the Emergency Source of power for Building 1. The main breaker EMERG MAIN is common to all the ATS’s 1 thru 6.

The EMERG MAIN breaker is codependent on the Normal Source of supply that feeds ATS1 in that the downstream breakers must work with either source of supply.

Not having an instantaneous component allows the EMERG MAIN breaker to have selective coordination with the six downstream ATS feeder breakers.

The individual ATS feeder breaker does not, however, have selective coordination with the next downstream device. This is mainly due in part to each having instantaneous elements which do not readily coordinate without a significant amount of impedance between the overcurrent devices.

This ATS is part of the Life Safety distribution system for Building 1. The National Electrical Code requires the Life Safety system to have selective coordination which means a single system’s fault will limit any power outage to the small part of the system. The present system does not comply with the

NEC requirements. Any corrective action would be extensive and would require a study to determine the most cost effective manner to remedy this non‐compliant condition.

Bldg 1 TCC N ATS1‐1

This TCC addresses the normal source of power for ATS 1. This curve is very similar to that of Bldg 1 TCC

E ATS1‐1 in that the main breaker achieves selective coordination with the downstream breakers, but after that, selective coordination is not achieved again due to the cascaded breakers having instantaneous elements.

Bldg 1 TCC N ATS1‐2

This curve covers more breakers downstream of the ATS. These breakers have thermal magnetic elements which are not adjustable. The fixed settings limit any ability to enhance performance between the individual breakers. For high magnitude faults, the instantaneous elements become functional and, based on these curves, selective coordination is not achieved.

Bldg 1 TCC N ATS1‐3

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This curve addresses the bus riser and the fused bus plugs. The fuse provides selective coordination for lower system faults but selectivity is not assured with the upstream breakers under high fault conditions.

Bldg 1 TCC N ATS1‐4

This TCC covers the feeder to Panel E1 in Building 12. Again selective coordination is not achieved.

Bldg 1 TCC N ATS1‐1G

This TCC addresses ground relaying for the three breakers that have ground relaying. Selective coordination is achieved for these breakers for ground faults. Due to the Normal Main breaker and corresponding Emergency Main Breaker source, the six (6) ATSs emphasis has been placed on assuring selective coordination is obtained at this level.

Upstream ground fault relaying is not present in the other overcurrent devices.

Building 1 ATS 2 ‐ Time Current Curves

Bldg 1 TCC E ATS2‐1

This TCC represents the Emergency Source of power for Building 1. The main breaker EMERG MAIN is common to all the ATS’s 1 thru 6.

The EMERG MAIN breaker is codependent on the Normal Source of supply that feeds ATS1 in that the downstream breakers must work with either source of supply.

Not having an instantaneous component allows EMERG MAIN breaker to have selective coordination with the six ATS feeder breakers.

The individual ATS feeder breaker, however, does not have selective coordination with the next downstream device. This is mainly due in part to each having instantaneous elements which do not readily coordinate without a significant amount of impedance between the overcurrent devices.

This ATS is part of the Critical Bus distribution system for Building 1. The National Electrical Code requires the Life Safety system to have selective coordination which means a single system’s fault will limit any power outage to the small part of the system. The present system does not comply with the

NEC requirements. Any corrective action would be extensive and would require a study to determine the most cost effective manner to remedy this non‐compliant condition.

Bldg 1 TCC N ATS2‐1

This TCC address the normal source of power for ATS 1. This curve is very similar to that of Bldg 1 TCC E

ATS1‐1 in that the main breaker achieves selective coordination with the downstream breakers; but

Protective Device Coordination Study Page 7 after that, selective coordination is not achieved for high magnitude faults again due to the cascaded breakers…