Vertiv™ | Liebert
®
STS2
™
100-1000A, 50/60Hz User Manual | Rev. 12 | 11/2017 109
15.2.4 Access
The Liebert STS2 is designed so all repairs and maintenance can be done from the front or top of the unit. All
components that may need repair or replacement during routine field maintenance are safely accessed with the
units in bypass without removing power from the unit. These components include:
• All electronic PCB assemblies
• Power supply assemblies
• All fuses
• All circuit breaker plug-in modules
•Fans
•SCRs
All power connections are designed to maintain proper connection torque over the lifetime of the unit without
any maintenance. The integrity of the connections can be checked via infrared scanning safely from the front or
top of the unit.
All other components including power cables and connections, circuit breaker bases, etc. are replaceable from
the front or top of the unit only, but this requires all power to be removed from the unit for safety. Although
routine re-torquing of the power connections is not required, if maintenance of these connections is needed,
complete removal of power is required from the unit for safety reasons.
15.2.5 Circuit Breakers
The Liebert STS2 is equipped with five molded-case, plug-in, non-automatic circuit breakers. The breakers are
UL-listed for use up to 600 VAC and CE-marked. The plug-in feature of the breaker includes an interlock, which
prevents the breaker from being unplugged without being in the OFF (open) position.
Mechanical interlocks are provided on the breakers to prevent improper maintenance bypassing of the solid-
state switch. A bypass breaker cannot be closed unless the solid-state switch is connected to the same input
source and only one bypass breaker can be closed at a time. All breakers are equipped with N.O. and N.C.
auxiliary switches for monitoring of the breaker positions. The two input breakers for the solid-state switching
devices also are equipped with 48 VDC shunt trips to allow for control by the Liebert STS2 logic. See submittal
drawing PS214002 for circuit breaker schedule.
15.2.6 Cable Entrance
Removable conduit termination plates are provided in the top and bottom of the Liebert STS2 for termination of
the two source input conduits or raceways and/or the output conduits or raceways.
15.2.7 Doors
A removable key lock hinged front door provides access to the circuit breakers.
15.2.8 Color Graphical Display or LED Display
The display is located in the front of the unit. Front panel display is either an LCD touchscreen display for
monitoring and configuring the unit, or an LED panel to monitor the unit’s status.
See Figure 41 for a drawing of the touchscreen display. See Figure 57 for the layout of the LED display.
WARNING
Lethal voltages exist inside the unit during normal operation. Only qualified service personnel should
perform maintenance on the static switch.
The unit is supplied by more than one power source. The unit contains hazardous voltages if any of the
input sources is ON, even when the unit is in bypass. To isolate the unit, turn OFF and lock out ALL input
power sources.
Verify that all input power sources are de-energized and locked out before making connections inside
unit.
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