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Radar System Engineering

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SEC. 1410] FIXED LOCATIONS 583<br />

portions of the installation require fixed frequency, consider an<br />

auxiliary d-c to a-c motor-alternator.<br />

3. Use electronic voltage regulation for engine generators or motor<br />

alternators.<br />

4. Consider vibrators for small loads.<br />

GROUND AND SHIPBOARD SYSTEMS<br />

Power for ground radar systems should be obtained from commercial<br />

electric service whenever possible, with certain precautions outlined<br />

below. The general problem of power supply for ground radar falls into<br />

four main groupings:<br />

1. Fixed locations with commercial electric service available.<br />

2. Large systems (with requirements for highly dependable service<br />

under all conditions) at fixed locations without commercial electric<br />

service, or for mobile use.<br />

3. Small systems for use in fixed locations without commercial power,<br />

or for mobile use.<br />

4. Small ultraportable mobile sets.<br />

In selecting a specific engine-generator set, or any specific alternator,<br />

serious consideration must be given to the specifications of the set (the<br />

alternator in particular) if satisfactory performance and characteristics<br />

are to be obtained. One good tabulation of standard Army power supplies<br />

is Signal “Corps Manual TM 11-223. However, most of the sets<br />

listed therein were not originally designed with radar in mind. Accordingly,<br />

their electrical performance may not meet radar needs without<br />

modification. A fuller discussion of the factors involved in choosing<br />

alternators and engine-generator sets is given in Vol. 17, Chap. 12, Radiation<br />

Laboratory Series.<br />

14.10. Fixed Locations.-Commercial power supply for radar installations<br />

must be provided with three major considerations in mind: (1) reliability<br />

required, (2) voltage stability of supply, (3) interference from<br />

common loads.<br />

Reliability.—If extremely reliable service must be provided, commercial<br />

service from a first-grade public utility is most satisfactory, provided<br />

that it is backed up by emergency feeders duplicating normal<br />

service (preferably by an alternate route) to a network station of the<br />

public-utility system. An emergency engine-alternator set (which may<br />

be made automatic-starting if deemed necessary) should also be provided.<br />

This arrangement is preferable to constant reliance on local generation.<br />

A regular maintenance schedule must be followed, with the emergency<br />

engine operated for a minimum of one hour per week at no load and a

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