UFC 3 -520-01
June 10, 2002
CHAPTER 3 GENERAL POWER SYSTEM CRITERIA
Paragraph
3-1
CHARACTERISTICS......................................................................
3-1
3-1.1
Voltage ............................................................................................
3-1
3-1.2
Frequency .......................................................................................
3-2
3-1.3
Power Factor...................................................................................
3-2
3-1.4
Neutral Conductor Grounding ........................................................
3-2
3-2
NORMAL POWER SOURCE.........................................................
3-2
3-3
ALTERNATE AND BACKUP POWER SOURCE ..........................
3-4
3-4
SERVICES......................................................................................
3-5
CHAPTER 4 POWER DISTRIBUTION AND UTILIZATION--TRANSFORMERS
Paragraph
4-1
RATINGS ........................................................................................
4-1
4-1.1
Introduction .....................................................................................
4-1
4-1.2
Voltage and Current........................................................................
4-1
4-1.3
Temperature and kVA ....................................................................
4-2
4-1.4
Impedance ......................................................................................
4-4
4-1.5
Number of Phases ..........................................................................
4-4
4-1.6
Transformer Taps ...........................................................................
4-4
4-1.7
Noise ...............................................................................................
4-5
4-1.8
Basic Impulse Insulation Levels (BILs) ..........................................
4-6
4-2
LOW VOLTAGE TRANSFORMERS..............................................
4-6
4-3
MEDIUM VOLTAGE TRANSFORMERS .......................................
4-7
4-4
OTHER TRANSFORMERS............................................................
4-7
4-4.1
Isolation Transformers....................................................................
4-7
4-4.2
Buck-Boost Transformers...............................................................
4-8
4-4.3
K-Factor Transformers ...................................................................
4-9
4-4.4
Specialty Transformers...................................................................
4-10
4-5
TRANSFORMER INSTALLATION CRITERIA ...............................
4-10
4-5.1
Introduction .....................................................................................
4-10
4-5.2
Dry-Type Transformers ..................................................................
4-10
4-5.3
Less-Flammable, Liquid- Insulated, and Oil- Insulated
Transformers...................................................................................
4-12
4-5.4
Fire Protection Criteria....................................................................
4-12
4-6
TRANSFORMER SIZING ...............................................................
4-12
4-7
INFORMATION SOURCES............................................................
4-13
CHAPTER 5 POWER DISTRIBUTION AND UTILIZATION--SWITCHGEAR, LOAD
CENTERS, AND BREAKERS
Paragraph
5-1
SERVICE ENTRANCE ...................................................................
5-1
5-2
SWITCHGEAR AND SWITCHBOARDS GENERAL CRITERIA ...
5-2
5-3
HIGH VOLTAGE SWITCHGEAR ...................................................
5-3
5-4
MEDIUM VOLTAGE SWITCHGEAR .............................................
5-4
5-4.1
Ratings ............................................................................................
5-4
5-4.2
Low Voltage Conductors in Medium Voltage Switchgear..............
5-6
5-5
LOW VOLTAGE BREAKERS AND PANELS ................................
5-6
5-6
MOTOR CONTROL CENTERS.....................................................
5-9
5-7
DISCONNECT SWITCHES............................................................
5-9
5-8
CIRCUIT LOCKOUT REQUIREMENTS ........................................
5-10
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