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cabinet's intended use. The breaker current ratings and maximum current that the UPS will pull from
the batteries while supporting the rated UPS load are shown in Table 11:
Table 11 Battery Cabinet Amp Ratings vs. UPS KVA Rating
UPS KVA
Rating
Breaker current trip rating on UPS
and Battery Cabinet
Max Current from batteries while
supporting rated UPS load
10KVA 80
50
15KVA 100
70
20KVA 150
100
25KVA 200
120
30KVA 225
140
50KVA 350
240
The breaker trip rating is approximately 50% higher than the maximum current drawn from the batteries
while supporting the rated UPS load. This over-rating is necessary to avoid nuisance trips in the
breakers should the UPS be overloaded periodically up to as much as 300% for very short periods of
time or up to 150% for 1 minute.
Wiring Diagrams:
Before beginning any work inside a Mesta Battery Cabinet, review the configuration
of the batteries in the cabinet to prevent any personal injury. Figure 12 shows the three wiring
configurations of Mesta battery cabinets. Figure 12a details a BC40-38, which contains two strings of
batteries, each string taking two shelves. A BC20-38 is similar to a BC40-38, except there is only one
string of batteries residing on the lower two shelves. Figure 12b shows a BC100-38 Mesta Battery
cabinet which contains five strings of batteries with one string of batteries per shelf. The BC60-38 and
BC80-38 cabinets have three and four strings/shelves of batteries, respectively, always placed from the
bottom up. Figure 12c shows a BC40-65 Mesta Battery Cabinet. The BC20-38 and BC40-38 are
similar to the BC20-38 and BC40-38 battery cabinets, except for the number of batteries in each string.
