fault current availability at the site.] [The Contractor shall utilize the
fault current availability indicated as a basis for fault current studies.]
2.23.3
Single Line Diagram
A single line diagram shall be prepared to show the electrical system
buses, devices, transformer points, and all sources of fault current
(including generator and motor contributions). A fault-impedance diagram
or a computer analysis diagram may be provided. Each bus, device or
transformer point shall have a unique identifier. If a fault-impedance
diagram is provided, impedance data shall be shown. Locations of switches,
breakers, and circuit interrupting devices shall be shown on the diagram
together with available fault data, and the device interrupting rating.
2.23.4
Fault Current Analysis
The fault current analysis shall be performed in accordance with methods
described in IEEE Std 242 and IEEE Std 399. Actual data shall be utilized
in fault calculations. Bus characteristics and transformer impedances
shall be those proposed. Data shall be documented in the report.
2.23.5
Fault Current Availability
Balanced three-phased fault, bolted line-to-line fault, and line-to-ground
fault current values shall be provided at each voltage transformation point
and at each power distribution bus. The maximum and minimum values of
fault available at each location shall be shown in tabular form on the
diagram or in the report.
2.23.6
Coordination Study
The study shall demonstrate that the maximum possible degree of selectively
has been obtained between devices specified, consistent with protection of
equipment and conductors from damage from overloads and fault conditions.
The study shall include a description of the coordination of the protective
devices in this project. Provide a written narrative that describes:
which devices may operate in the event of a fault at each bus; the logic
used to arrive at device ratings and settings; situations where system
coordination is not achievable due to device limitations (an analysis of
any device curves which overlap); coordination between upstream and
downstream devices; and relay settings. Recommendations to improve or
enhance system reliability, and detail where such changes would involve
additions or modifications to the contract and cost changes (addition or
reduction) shall be provided. Composite coordination plots shall be
provided on log-log graph paper.
2.23.7
Study Report
a.
The report shall include a narrative describing: the analyses
performed; the bases and methods used; and the desired method of
coordinated protection of the power system.
b.
The study shall include descriptive and technical data for
existing devices and new protective devices proposed. The data
shall include manufacturers published data, nameplate data, and
definition of the fixed or adjustable features of the existing or
new protective devices.
c.
The report shall document [utility company data including system
SECTION 16370A
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