User's Manual

Initial Power-up
68P09255A69-3
Aug 2002
1X SC4812ET Lite BTS Optimization/ATP Software Release 2.16.1.x
PRELIMINARY
2-16
Battery Charge Test (Connected Batteries)
Table 2-7 lists the step-by-step instructions for testing the battery
charging performance.
Table 2-7: Battery Charge Test (Connected Batteries)
Step Action
1 Close the battery shelf circuit breakers (Figure 2-3) for connected batteries only. This process should
be completed quickly to avoid individual battery strings drawing excess charge current
NOTE
If the batteries are sufficiently discharged, the battery circuit breakers may not engage individually
due to the surge current. If this condition occurs, disconnect the batteries from the 27Vdc bus by
setting the MAP power switch to OFF, and then engage all the connected battery circuit breakers.
The MAP power switch should then be turned ON.
2
Using the clamp-on DC current probe and DMM, measure the current in each of the battery string
connections to the battery bus bars. The charge current may initially be high but should quickly
reduce in a few minutes if the batteries have a typical new-battery charge level.
NOTE
The MAP AMP display will indicate the total current output of the rectifiers during this procedure.
As an alternative, the bar graph meters on the AC rectifier modules can be used as a rough estimate of
the total battery charge current. Each rectifier module bar graph has eight (8) LED elements to
represent the output current. Each illuminated LED element indicates that approximately 12.5% (1/8
or 8.75 Amps) of an individual rectifier’s maximum current output (70 Amps) is flowing.
RECTIFIER BAR GRAPH EXAMPLE:
Question: A system fitted with three (3) rectifier modules each have three bar graph LED elements
illuminated. What is the total output current into the batteries?
Answer: Each bar graph is indicating approximately 12.5% of 70 amps, therefore, 3 x 8.75 equals
26.25 amps per rectifier. As there are three rectifiers, the total charge current is equal to (3 x 26.25 A)
78.75 amps.
This charge current calculation is only valid when the RF and LPA compartment electronics are not
powered on, and the RF compartment heat exchanger is turned off. This can only be accomplished if
the DC PDA MAIN BREAKER is set to OFF.
3 The current in each string should be approximately equal (within + 5 amps).
4 Allow a few minutes to ensure that the battery charge current stabilizes before taking any further
action. Recheck the battery current in each string. If the batteries had a reasonable charge, the current
in each string should reduce to less than 5 amps.
5
Recheck the DC output voltage. It should remain the same as measured in step 4 of the frame DC
Power Application and Test (Table 2-6).
NOTE
If discharged batteries are installed, the MAP AMP display may indicate approximately 288 amps for
a two-carrier frame (four rectifiers) or 216 amps for a single-carrier frame (three rectifiers).
Alternately, all bar graph elements may be lighted on the rectifiers during the charge test. Either
indication shows that the rectifiers are at full capacity and are rapidly charging the batteries. It is
recommended in this case that the batteries are allowed to charge and stabilize as in the above step
before commissioning the site. This could take several hours.
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