System Start - ABB HiPerGuard MV UPS User Manual

74 H I P E R G U A R D M V U P S U S E R M A N U A L
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8.2 System Start

To start the MV UPS(s), the system needs to be precharged. Hence, the user has to check the system state and ei-
ther by:
1. Precharging the system
by following the precharge instructions till sufficient precharge conditions are met (example: system
start after maintenance)
2. Starting the system right away if the system was already precharged (example: system start after a
brief stop).
8.2.1 DC bus precharge
Before a MV UPS system can be started, the energy storage must be precharged and connected. Precharging is re-
quired if the DC bus has been disconnected from energy storage (batteries) and has been allowed to discharge. If
the battery circuit breaker is closed while the DC bus capacitors are in a discharged state, the resulting current in-
rush may cause damage or tripping of switchgear.
The control logic will be configured with knowledge of how many battery strings are required (sufficient) and the
level of voltage required. "Sufficient" may allow the system to be started in a reduced capacity mode with Warn-
ings present, for example, with less than full complement of battery strings connected.
Before commencing precharge, check to ensure the HiPerGuard MV UPS(s) is (are) in "Bypass isolate mode", as
shown in Figures 8.02 and 8.03. Table 8.01 describes the precharging steps.
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Figure 8.02: MV UPS
system in bypass
and isolated.
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Figure 8.03: MV UPS
system (hard parallel)
in bypass and isolated.