2.19.3
Single Line Diagram
A single line diagram shall be prepared to show the electrical system
buses, devices, transformation 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
transformation 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.
2.19.4
Fault Current Analysis
2.19.4.1
Method
The fault current analysis shall be performed in accordance with methods
described in IEEE Std 242, and IEEE Std 399.
2.19.4.2
Data
Actual data shall be utilized in fault calculations. Bus characteristics
and transformer impedances shall be those proposed. Data shall be
documented in the report.
2.19.5
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 any 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.
2.19.6
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
voltages, fault MVA, system X/R ratio, time-current characteristics
curves, current transformer ratios, and relay device numbers and
settings;] [and] [existing power system data including time-current
characteristic curves and protective device ratings and settings.]
d.
The report shall contain fully coordinated composite time-current
SECTION 16375A
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