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TN102 - Data Center Power

 
 
102.1   Summary
102.2   Typical Connectors
102.3   Three Phase Power
102.4   Strain Relief for Vertical Hanging Cables
102.5   Load
102.6   Power Quality/Grounding
102.7   Rack Mount Power Control/Distribution

102.1 Summary

Various specifications and sources for power distribution in the data center.  
 
 
 

102.2 Typical Connectors

NEMA standards prevents plug/outlet interchange between current or voltage ratings. The IEC 60320 standard (formerly called 320) defines the international power connectors typically used for computer equipment.

Locking blade (twist-lock) power plugs are normally used to connect power to computer racks. The locking blades also prevent accidental disconnection.

Type Plug Receptacle
IEC 60320 C13/14
120/240 volt, Single Phase
3 wire, grounding
10 amp
IEC 320 C14
C14
IEC 320 C15
C13
IEC 60320 C19/20
120/240 volt, Single Phase
3 wire, grounding
16 amp
IEC 320 C20
C20
IEC 320 C19
C19
NEMA 5-15
120 volt, Single Phase
3 wire, grounding
15 amp
5-15P 5-15R
NEMA L5-20
120 volt, Single Phase
3 wire, grounding
20 amp
L5-20P L5-20R
NEMA L6-20
240 volt, Two Pole
3 wire, grounding
20 amp
L6-20P L6-20R
NEMA L6-30
240 volt, two pole
3 wire, grounding
30 amp
L6-30P L6-30R
NEMA L15-20
240 volt, 3Ø,
three pole, 4 wire,
grounding
20 amp
L15-20P L15-20R
NEMA L15-30
240 volt, 3Ø,
three pole, 4 wire,
grounding
30 amp
L15-30P L15-30R
NEMA L21-20
120/208 volt, 3ØY,
four pole, 5 wire,
grounding
20 amp
L21-20P L21-20R
NEMA L21-30
120/208 volt, 3ØY,
four pole, 5 wire,
grounding
30 amp
L21-30P L21-30R

G - Ground,  W - Neutral,   X,Y,Z - Service Poles
 
 
 
 

102.3 Three Phase Power

For North Amercia data centers, three phase power is typicaly either 240 volt delta or 208Y/120 volt wye.
208Y/120 volt
Wye
(four pole)
Wye
240 volt
Delta
(three pole)
Delta
 
 
 
 

102.4 Strain Relief for Vertical Hanging Cables

Cable Grips
Hubbell Bryant

Cable Grip
 
 
 
 

102.5 Load

It is often difficult to know if a given rack overloaded. Traditional clamp meters require access to single conductor. Load can be measured in multi-core cables using the Megger MMC850.  
 
 
 

102.6 Power Quality/Grounding

An excellent tutorial on power quality: Power Quality Primer.

The LEM GEO MODEL 15: Ground Resistance Tester from LEM Instruments can measure ground quality without disconnecting the circuit. They also have a tutorial on grounding: Ground Resistance Principles, Testing, Techniques & Applications  
 
 
 

102.7 Rack Mount Power Control/Distribution

 
 
 
 
 
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