standards and guidelines for communication sites - Radio And ...

CHAPTER
6
POWER SOURCES 6
6.1 LOCKOUT/TAGOUT
6.2 AC POWER
This chapter describes various types of power systems that are used for communications sites. It
also specifies requirements for various types of power systems that are typically used at a
communication site. The following topics are included:
• “Lockout/Tagout” on page 6-1
• “AC Power” on page 6-1
• “Power Quality” on page 6-11
• “Rectifier/DC Power Systems” on page 6-19
• “Uninterruptible Power Supplies” on page 6-24
• “Alternate Power Sources” on page 6-25
• “Battery Systems” on page 6-27
• “Standby Generator Systems” on page 6-35
• “Generator Output and Derating Considerations” on page 6-36
On all power systems (AC or DC), a provision shall be present to lock out and tagout any circuit
to help ensure the circuit is safe to work on. (See NFPA 70-2005 for additional information.)
All AC power systems shall be designed, installed and maintained in accordance with
jurisdictional standards and regulations.
All site power loading shall be determined for initial equipment installation and future
expansion. The determined loads at various locations throughout the site shall then be factored
into the site electrical design.
Continuous load shall not exceed 80% of the electrical system, (wire, panel board, breakers, and
service rating). Using this standard allows all participants in site design (electric power
company, prefabricated shelter vendor, UPS vendor, generator vendor, etc.) to ensure that the
power capacity supplied to the communications site is adequate.
Minimum acceptable service for US installations is typically 100 amps @ 120/240 VAC (or 120/
208 VAC). A 200 amp (or larger) service may be required for existing/future loads or for
additional circuit breaker positions. (Other service parameters may be applicable for
nondomestic installations.)
Sizing of AC power loads is critical in calculating supply capacity. Typical power needs are:
• HVAC system (including redundant units). Most sites consisting of shelters will not be
continuously occupied. In such case, the service personnel heat load need not be considered.
• Room lights and possible outdoor security lighting
68P81089E50-B 9/1/05 6-1