Liebert Static Transfer Switch 2, Installation, Operation & Maintenance Manual

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Specifications 109
15.2 System Components
All STS2 models provide two static transfer switches within one enclosure, with the ability to trans-
fer between two input sources to a single output.
All STS2s are configured with either an LCD Color Graphical Interface touch screen display or
LEDs for monitoring and configuring the unit.
This section lists the common components and the differences for both types of units.
15.2.1 Frame and Enclosure
The complete STS2 is housed in a freestanding enclosure. The cabinet is a NEMA type 1 enclosure
and meets IP20 requirements. The cabinet is structurally designed to handle lifting from the base.
The frame is designed to accommodate floor stands.
The distributed floor weight for STS2 is less than 150 lbs./sq. ft. (660kg/m²).
The required service access is only from the front of the unit.
The STS2 can be tipped 15° in any direction without falling over.
15.2.2 Castors, Leveling and Seismic Anchoring
The frame includes heavy-duty swivel castors for ease of installation, plus permanent leveling feet
for final installation.
The unit also can be fastened to the floor using optional seismic anchors to meet seismic Zone 4
requirements. See
4.0 - Locating the STS2 on page 12 and Figure 11 on page 29 through
Figure 13 on page 31 for instructions and details for installing seismic anchoring.
15.2.3 Cooling
The STS2 100 – 600A units utilize convection air cooling for the enclosure with forced air cooling of
the heat sinks. The 800-1000A units are fan cooled using low-velocity fans to minimize audible
noise. All fans are redundant so that a single fan failure cannot cause temperatures to increase
beyond acceptable limits.
Air intake is through screened protective openings in the front of the unit. A standard furnace filter
is installed behind the openings.
By opening the front door, the filter can be changed easily without exposing personnel to high volt-
age.
The size of the filter is 1 in. x 25 in. x 25 in. (2.54 cm x 63.5 cm x 63.5 cm).
The air exhaust is through the top of the unit.
Table 22 Frame Sizes
Rating Width Depth Height
100 – 250A 3 pole 30 in (76 cm) 32 in (81 cm) 76.77 in (195 cm)
400 – 600A 3 pole 38 in (96 cm) 32 in (81 cm) 76.77 in (195 cm)
800 – 1000A 3 pole 84 in (213 cm) 32 in (81 cm) 76.77 in (195 cm)