Thomas & Betts 9395 - Manual (Page 17)

UPS 225 - 275 kVA
User’s and Installation Guide
1027212
Revision B 17
The line-to-line unbalanced output capability of the UPS is limited only by the full load per
phase current values for AC output to critical load shown in Table 2-4. The recommended line-to-
line load unbalance is 50% or less.
Source protection for the AC input to bypass should be treated as if supplying a 275 kVA three-
phase transformer, to allow for inrush current. Bypass input wiring and bypass input breaker
rating should be treated as if supplying a 275 kVA load, regardless of the rating of the UPS.
Bypass and output overcurrent protection and bypass and output disconnect switches are to
be provided by the user. Table 2-8 lists the recommended rating for bypass and output circuit
breakers satisfying the criteria for both.
UPS model
Rating
Load rating
400 V
Bypass Output
9395-275/225 100% rated 400 A 80 A (B-type braker)
9395-275/275 100% rated 500 A 100 A (B-type breaker)
Table 2-8. Recommended bypass and output circuit breaker ratings
There is no DC disconnect device within the UPS. A battery disconnect switch is recommended,
and may be required by local codes when batteries are remotely located. The battery disconnect
switch should be installed between the battery and the UPS.
External DC input overcurrent protection and disconnect switch for the remote battery location
is to be provided by the user. Table 2-9 lists the maximum rating for continuous-duty rated
circuit breakers satisfying the criteria for both.
UPS model
Input rating
600 V
9395-275/225 500 A or 700 A for ugradeability
9395-275/275 700 A
Table 2-9. Recommended DC input circuit breaker ratings
Battery voltage is computed at 2 volts per cell. Rated battery current is computed at 2 volts per
cell. The battery wiring used between the battery and the UPS should not allow a voltage drop
of more than 1% of nominal DC voltage at rated battery current. If the conductors used for DC
input from the battery cabinets to the UPS are those provided by the UPS manufacturer, and the
UPS and battery cabinets are manufactured by the same supplier, then it is acceptable if they
do not meet the noted minimum conductor sizes.
2.2.3 UPS system interface wiring preparation
Control wiring for features and options should be connected at the customer interface terminal
blocks located inside the UPS.
WARNING
Do not directly connect relay contacts to the mains related circuits. Reinforced insulation to
the mains is required.