Vertiv Liebert STS2 - Access

Vertiv™ | Liebert® STS2/PDU
™
User Manual | Rev. 6 | 10/2017 118
14.2.4 Access
The Liebert STS2/PDU is designed so repairs and maintenance can be done from the front, side 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 control 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 transformers, power cables and connections, circuit breaker bases, etc., are
replaceable from the front, rear or top of the unit, 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.
14.2.5 Circuit Breakers
The Liebert STS2/PDU is equipped with two input plug-in circuit breakers and five or six (if CB3A is used)
molded-case, plug-in, non-automatic circuit breakers. The breakers are UL listed for use up to 600VAC 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 solid-state static switch input breakers are
equipped with 48 VDC shunt trips to allow for control by the Liebert STS2/PDU logic. See Tables 10 through 12.
14.2.6 Cable Entrance
Removable conduit termination plates are provided in the top and bottom of the Liebert STS2/PDU for
termination of the two source input conduits or raceways and/or the output conduits or raceways. On units with
inline panelboards, output conduit or raceways are bottom exit only.
14.2.7 Doors
A removable key lock hinged front door provides access to the circuit breakers.
WARNING
Risk of electric shock. Can cause injury or death.
Lethal voltages exist inside the unit during normal operation. Only properly trained and
qualified service personnel should perform maintenance on the Liebert STS2/PDU.
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.