User's Manual

Navini Networks, Inc. Ripwave Base Station I&C Guide
Part #40-00047-00 Rev D v1.0 203
February 28, 2003
Backup Power System
General
Backup power systems provide a means of extending operations of the installed equipment
during periods of extended commercial power failure. Backup power systems may be as simple
as providing a combination of suitably sized rectifiers and DC storage batteries, or may include
more complicated site installed generators in combination automatic transfer switches, and
storage batteries.
Rectifiers
The AC/DC rectifier(s) should be chosen based on power delivered to the load(s). For example,
the DC Power requirements listed for the Base Station RF & Digital chassis may be just part of
the overall power requirement. It is recommended that the AC/DC rectifier’s rating exceed the
expected load by some 20%, or per the rectifier manufacturer’s guidelines based on
consideration not limited to expected load, temperature range, and reliability.
Storage Batteries
Storage batteries provide variable capacity backup power to extend installed equipment
operations. Storage batteries utilized for outdoor, uncontrolled environment operations normally
consist of valve regulated lead acid batteries. The selection of storage batteries depends on a
combination of factors that may include, but are not limited to
• The surrounding environmental conditions in which the outdoor cabinet will be placed;
• The amount of backup time desired by the customer;
• The stability of the local power grid;
• The historical duration of commercial power outages; and
• Local environmental regulations.
Low Voltage Disconnect
Low voltage disconnect should be provided to protect the batteries & the Base Station equipment
once the batteries reach the manufacturer’s rating for minimum cell voltage. The Base Station is
rated to 20VDC minimum. It should be noted that as battery voltage declines, the current
demanded increases as power required remains constant.
Generator
Power generators provide an alternative for back-up power. Generator ratings are again based on
the power required by the loads, which, as mentioned above, include the Base Station RF &
Digital chassis as well as other supporting equipment. Consult with the manufacturer’s
recommendations when selecting a particular generator based on required installation.