Section 26 05 71 - Electrical System Protective Device Study.DOC
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- Attached to
- Misc. Generator Repairs and Improvements Federal contract opportunity
- Solicitation number
- 36C25621R0179
About this file
This document outlines specifications for an electrical system protective device study and related federal contract opportunity for generator repairs and improvements. The study requires a short-circuit and selective coordination analysis of overcurrent devices on one-line diagrams, along with time-current coordination curves and settings tables. It must be prepared by qualified engineers according to IEEE standards.
The federal opportunity is a total SDVOSB set-aside to furnish all labor, tools, materials, equipment, supervision and other requirements for miscellaneous generator repairs and improvements at the Gulf Coast Veterans Health Care System in Pensacola, Florida. Offerors must be registered and verified as an SDVOSB in VetBiz. Joint venture agreements must be included if proposing as a joint venture. The contract award will not be delayed due to loss of SDVOSB verification.
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Text version
09-10
SECTION 26 05 71
ELECTRICAL SYSTEM PROTECTIVE DEVICE STUDY
PART 1 ‑ GENERAL
1.1 DESCRIPTION
A.
This section specifies the requirements of the Electrical System Protective Device Study (herein, “the study”).
B.
A short-circuit and selective coordination study shall be prepared for the electrical overcurrent devices to be installed under this project.
C.
The study shall present an organized time‑current analysis of each protective device in series from the // individual device // // ____ // back to the utility// and the on-site generator sources//. The study shall reflect the operation of each device during normal and abnormal current conditions.
1.2 RELATED WORK
A.
Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS: General electrical requirements that are common to more than one section of Division 26.
B.
Section 26 13 00, MEDIUM-VOLTAGE SWITCHGEAR: Medium-voltage distribution switchgear.
C.
Section 26 18 41, MEDIUM-VOLTAGE SWITCHES: Medium-voltage switches.
D.
Section 26 23 00, LOW-VOLTAGE SWITCHGEAR: Low voltage switchgear.
E.
Section 26 24 11, DISTRIBUTION SWITCHBOARDS: Low-voltage distribution switchboards.
F.
Section 26 24 16, PANEL BOARDS: Low-voltage panelboards.
G.
Section 26 24 19, MOTOR CONTROL CENTERS: Low-voltage motor control centers.
H.
Section 26 32 13, ENGINE-GENERATORS: Engine-generators.
1.3 qualITY ASSURANCE
A.
Refer to Paragraph, QUALIFICATIONS, in Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS.
B.
The protective device study shall be prepared by the equipment manufacturer's qualified engineers or an approved consultant. The contractor is responsible for providing all pertinent information required by the preparers to complete the study.
1.4 SUBMITTALS
A.
In accordance with Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS, submit the following:
B.
Product data on the software program to be used for the study. Software shall be in mainstream use in the industry, shall provide device settings and ratings, and shall show selective coordination by time-current drawings.
C.
Complete short-circuit and coordination study as described in paragraph 1.6.
D.
Protective equipment shop drawings shall be submitted simultaneously with or after the protective device study. Protective equipment shop drawings will not be accepted prior to protective device study.
E.
Certification: Two weeks prior to final inspection, submit four copies of the following to the //Resident Engineer// //COTR//:
Certification by the contractor that the protective devices have been adjusted and set in accordance with the approved protective device study.
1.5 APPLICABLE PUBLICATIONS
A.
Publications listed below (including amendments, addenda, revisions, supplements, and errata) form a part of this specification to the extent referenced. Publications are referenced in the text by designation only.
B.
Institute of Electrical and Electronics Engineers (IEEE):
242-01 Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems
399-97 Recommended Practice for Power Systems Analysis 1584a-04 Guide for Performing Arc-Flash Hazard Calculations SPEC WRITER NOTE: On small renovation projects, modify the scope to describe the proper extent of the study.
1.6 REQUIREMENTS
A.
The complete study shall include a system one line diagram, short-circuit and ground fault analysis, and protective coordination plots for all overcurrent protective devices up to and including the emergency distribution panel.
B.
One Line Diagram:
1.
On the one line diagram, show all electrical equipment and wiring to be protected by the overcurrent devices installed under this project.
2.
On the one line diagram, also show the following specific information:
a.
Calculated fault impedance, X/R ratios, and short-circuit values at each feeder and branch circuit bus.
b.
Breaker and fuse ratings.
c.
Generator kW and Transformer kVA and voltage ratings, percent impedance, X/R ratios, and wiring connections.
d.
Voltage at each bus.
e.
Identification of each bus, matching the identification on the construction drawings.
f.
Conduit, cable, and busway material and sizes, length, and X/R ratios.
C.
Short-Circuit Study:
1.
Systematically calculate the fault impedance to determine the available short-circuit and ground fault currents at each bus. Incorporate the motor contribution in determining the momentary and interrupting ratings of the protective devices.
2.
The study shall be calculated by means of a computer program. Pertinent data and the rationale employed in developing the calculations shall be incorporated in the introductory remarks of the study.
3.
Present the data conclusions of the short-circuit study in a table format. Include the following:
a.
Device identification.
b.
Operating voltage.
c.
Protective device.
d.
Device rating.
e.
Calculated short-circuit current.
D.
Coordination Curves:
1.
Prepare the coordination curves to determine the required settings of protective devices to ensure selective coordination. Graphically illustrate on log‑log paper that adequate time separation exists between series devices, including the utility company upstream device. Plot the specific time‑current characteristics of each protective device in such a manner that all upstream devices are clearly depicted on one sheet.
2.
The following specific information shall also be shown on the coordination curves:
a.
Device identification.
b.
Voltage and current ratio for curves.
c.
3‑phase and 1‑phase ANSI damage points for each transformer.
d.
No‑damage, melting, and clearing curves for fuses.
e.
Cable damage curves.
f.
Transformer in-rush points.
g.
Maximum short-circuit cutoff point.
3.
Develop a table to summarize the settings selected for the protective devices. Include the following in the table:
a.
Device identification.
b.
Relay CT ratios, tap, time dial, and instantaneous pickup.
c.
Circuit breaker sensor rating, long‑time, short‑time, and instantaneous settings, and time bands.
d.
Fuse rating and type.
e.
Ground fault pickup and time delay.
1.7 ANALYSIS
A.
Analyze the short-circuit calculations, and highlight any equipment determined to be underrated as specified. Propose approaches to effectively protect the underrated equipment. Provide minor modifications to conform with the study (examples of minor modifications are trip sizes within the same frame, the time-current curve characteristics of induction relays, CT ranges, etc.).
B.
After developing the coordination curves, highlight areas lacking coordination. Present a technical evaluation with a discussion of the logical compromises for best coordination.
1.8 ADJUSTMENTS, SETTINGS AND MODIFICATIONS
A. Necessary final field adjustments, settings, and minor modifications shall be made to conform with the study without additional cost to the Government.
B. All final circuit breaker and relay settings and fuse sizes shall be made in accordance with the recommendations of the study.
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