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Guide for Architect Engineer Firms Performing Services for the Atlantic Division

Manholes and Handholes

LANTNAVFACENGCOM A&E GUIDE

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A.1.13

BREAKER/RELAY SETTINGS

a. The designer shall discuss proposed relay protection schemes,

including selection of relays and current transformer ratios, with

LANTNAVACENGCOM Code 163 during the design process.

b. The designer shall ensure that construction contract documents require

that the contractor submit manufacturer's published time-current

curves (on full size logarithmic paper) of primary fuses, relays, main

secondary breakers, and secondary feeder protective devices.

c. Upon completion of successful shop drawing review, the designer shall

properly select high side transformer fuses and provide settings for

main secondary breakers and secondary feeder protective devices. The

designer shall ensure that circuit components are adequately protected

against short circuits and ground faults and that protective devices are

properly coordinated. LANTNAVFACENGCOM Code 163 will be

available to assist the designer if required.

d. LANTNAVFACENGCOM Code 163 shall be directly responsible for

providing settings for protective relays and for selecting proper primary

fuses (except that high side transformer fuses shall be selected by the

designer). Required information will be forwarded to

LANTNAVFACENGCOM Code 163 by the designer upon completion

of successful shop drawing review.

e. Fuse selections and breaker/relay settings shall be promptly

determined and immediately forwarded to LANTNAVFACENGCOM

Code 05.

f. Please note that protective relays associated with Air Force and Army

bases are not the responsibility of LANTNAVFACENGCOM Code

163; the designer must obtain settings for these relays from the

appropriate command.

A.1.14

NON-LINEAR LOADS

Many types of data processing and office equipment, such as computers,

copiers, video display terminals, printers, and plotters, use switch-mode power

supplies (SMPS). While this technology provides significant reduction in

equipment losses, weight, volume, and cost, it also can cause problems in the

building electrical distribution system SMPS draw power from the source in

pulses during the peak of each voltage half-cycle, rather than continuously,

resulting in severe nonlinearity and high harmonic currents.

Attachment A-9