Emerson 250-400kVA - Manual (Page 29)

Operation
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2.3.6 Remote Emergency Power Off
The Remote Emergency Power Off (REPO) mode will transfer the critical load to the bypass line and
remove power from all UPS module components except the controls, bypass circuit breaker and the
static switch.
The Remote Emergency Power Off control is a user-provided switch located remotely from the UPS
system. It usually is installed in the same room as the critical load equipment. This mode can also be
initiated by an automatic contact closure in the same external circuit as the manually operated
switch.
When the Remote Emergency Power Off switch is operated, all UPS circuit breakers are opened,
including the bypass circuit breaker. All power through the UPS is removed from the load. Typically,
the REPO circuit also opens the circuit breakers that provide power to the bypass lines and the UPS
controls. Refer to 2.5 - Shutdown Procedures.
Figure 29 Remote emergency power off
2.4 Manual Procedures
The Liebert NXL UPS is designed to function while unattended by an operator. Many important func-
tions are handled automatically by the system control logic, as explained in 2.6 - Automatic Opera-
tions. Other procedures must be performed manually.
Manual procedures available to the operator include Startup, Load Transfers and Shutdowns. These
procedures are performed by using the touchscreen and some manually operated circuit breakers and
switches.
The touchscreen lists all steps required for each manual procedure. This section lists step-by-step con-
trols to operate and conditions to observe in the following manual procedures:
• Startup—including initial startup, recovering from input power failure, recovering from battery
shutdown and recovering from shutdowns for emergencies or maintenance.
• Load Transfers—including transfers from UPS to bypass and retransfers from bypass to the
UPS system.
• Maintenance Bypass Load Transfers—including transferring from internal bypass to mainte-
nance bypass and transferring from maintenance bypass to internal bypass.
• Shutdowns—including module shutdowns for maintenance and emergency shutdowns.
NOTE
The following procedure assumes that the UPS installation inspection and initial startup have
been performed by Liebert Services. A Liebert-authorized representative must perform the
initial system startup to ensure proper system operation.
Bypass
Battery
System
DC Bus
Module
Output
BFB
CB2 CB1
MBD
Input