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92 Operation
Power must be provided t o the UPS controls so the operator can use the LCD display and so the system logic can
perform its control functions. Note that you can use the LCD display to monitor UPS system status, even when
the UPS modules are not operating.
During a start-up procedure, power is supplied to the critical load through the UPS (internal) bypass line while
the UPS modules are being energized. Depending on the reason for your UPS system shutdown, you may already
have power through the bypass line. You can determine this by observing the Monitor/Mimic Display screen at
the System Control Cabinet (SCC).
Step 2. If the bypass line is not supplying the load, the LCD screen will be blank. Energize the bypass line by
operating the following controls:
a. Close the Bypass Input Breaker (BIB). This breaker may be in your Maintenance Bypass cabinet.
b. Observe the Monitor/Mimic Display screen to determine if your System Bypass circuit breaker (SBB)
is closed and whether the UPS Bypass line is supplying power to the critical load.
If your System Bypass circuit breaker is open (as in recovering from an Emergency Power Off or Low
Battery Shutdown), close this circuit breaker as follows:
b1. Open the SCC control panel door and find the Transfer Relay Board (Figure 11). If the red LED
(CR18) labeled TOT S/D (Total Shutdown) is on, press the Bypass Reset switch (SW1) on this
board. The red LED should turn off.
b2. Set the Static Switch Disconnects (Figure 9) OFF (open).
NOTE
If the system was shut down in response to an “Emergency Off, there may be alarm
messages on the LCD screen that describe system conditions before (or at the time of)
the shutdown. Some or all of the alarm conditions may have already been resolved.
To clear these alarm messages, turn off the control power (see Figure 8 and
Figure 9). Wait at least ten minutes for the control power circuitry to completely de-
energize. After ten minutes, turn control power back on and wait two minutes before
continuing.
CAUTION
If you are recovering from a UPS system shutdown for maintenance procedures,
verify that all of the SCC doors are closed and latched. All test equipment must
be removed from the system. All electrical connections must be secure.
NOTE
Wait two minutes after applying bypass power before you operate any other UPS
controls.
CAUTION
DO NOT assume that the UPS System Bypass Breaker (SBB) is closed.
Instructions for operating the Maintenance Bypass circuit breakers are on the
Maintenance Bypass cabinet.
Make sure you understand the proper sequence b efore operating any circuit
breaker. Operating a Maintenance Bypass circuit breaker o u t o f sequence cou ld
cut off power to the critical load.
NOTE
Depending on SCC model, the static switch disconnects can be two circuit breakers,
contactors or plug-in connections on a drawout carriage assembly. The location
could be at the front, right, or rear of the cabinet. Refer to the drawing of the SCC
cabinet selected for your UPS system.
DISCONTINUED
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