Specifications

100 – 1000 Amps
SL-20610 (R 11/02) 7
Provision shall be made for power and control cables to enter or leave from the top or bottom of the STS
cabinet.
2.1.3 Frame and Enclosure
The STS unit comprises of solid-state, three-pole, dual-position transfer switch, key-interlocked static
switch isolation and bypass breakers, shall be housed in a single free-standing NEMA type 1 enclosure
and meet IP20 requirements. The frame shall be constructed of galvanized steel and pop riveted to
provide a strong substructure. The frame shall include four heavy-duty swivel castors for ease of
installation and four permanent leveling feet for final installation. Doors and removable exterior panels
shall be a minimum of 16GA steel and be powder-painted the manufacturer’s standard color textured
enamel finish paint. Key lock hinged front door shall provide access to the circuit breakers. A tool shall
be required to remove exterior panels that expose hazardous voltages. All removable panels shall be
grounded to the frame for safety and EMI/RFI protection. The cabinet shall be structurally designed to
handle fork lifting from the base.
Front access only shall be required for expedient servicing, maintenance, and installation. The STS shall
be constructed of replaceable subassemblies that can be easily changed without exposing personnel to
high voltage. Printed circuit assemblies shall be plug connections.
Removable conduit/cable termination plates shall be provided in the top and bottom of the unit for
termination of the two source input and/or output conduits, raceways or cables.
The complete STS shall have maximum dimensions of [30 in./610 mm (up to 250 amps), 38 in./810 mm
(400A–600A,), 84 in./2134 mm (800A–100A)] wide by 32 in./810 mm deep by 77 in./1950 mm high.
The distributed floor weight shall be less than 150 lbs./sq. ft. (660 kg/m2).
The STS can be tipped 15 degrees in any direction without falling over.
2.1.4 Cooling (100-600A)
The STS shall utilize convection air cooling for the enclosure with forced air cooling of the heat sinks. All
fans shall be redundant so that a single fan failure will not cause temperature to increase beyond
acceptable limits. Heat rejection shall be through screened protective openings in the top of the unit. Air
filters shall be located in the front door at the point of air inlet.
Cooling (800-1000A)
Cooling of the STS shall be by forced air. Low-velocity fans shall be used to minimize audible noise
output. All fans shall be redundant so that a single fan failure will not cause temperature to increase
beyond acceptable limits. Heat rejection shall be through screened protective openings in the top of the
unit. Air filters shall be located in the front door at the point of air inlet
2.1.5 Grounding
The STS shall operate from sources that are solidly or impedance grounded. Unit shall not be used on
corner-grounded delta systems.
The AC output neutral shall be electrically isolated from the STS chassis. The STS chassis shall have an
equipment ground terminal.
2.2 COMPONENTS
2.2.1 Non-automatic Circuit Breakers