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CSI SECTION 16611 STATIC UNINTERRUPTIBLE SYSTEM
CSI SECTION 16611 STATIC UNINTERRUPTIBLE SYSTEM
2.7 AUTOMATIC BYPASS
A. As part of the UPS, a system automatic bypass switch shall be provided. The system
automatic bypass shall provide a break <11Ms transfer of the critical load from the
Inverter output to the automatic bypass input source during times where maintenance is
required, or the inverter can not support the critical bus. . Such times may be due to
prolonged or severe overloads, or UPS failure. The additional manual bypass switch
will have a no break transfer of critical loads from Inverter output to the manual bypass
switch which will correspondingly engage the automatic bypass switch driving it into
bypass position. The UPS shall constantly monitor the output current, as well as the
bypass source voltage, and inhibit potentially unsuccessful transfers to automatic
bypass from taking place.
B. The design of the automatic bypass switch power path shall consist of a heavy duty
electromechanical bypass contactor with a continuous duty rating up to 100A.
C. Automatic Transfers: An automatic transfer of load to bypass shall take place
whenever the load on the critical bus exceeds the overload rating of the UPS. Automatic
transfers of the critical load from bypass back to normal operation shall take place when
the overload condition is removed from the critical bus output of the system. Automatic
transfers of load to bypass shall also take place if for any reason the UPS cannot support
the critical bus.
D. Manual Transfers: Manually initiated transfers to and from s bypass shall be initiated
through the UPS display interface or by engaging the manual bypass switch on the front
of the unit.
E. Overloads: The automatic bypass shall be rated and capable of handling overloads
equal to or less than 100A continuously. For instantaneous overloads caused by inrush
current from magnetic devices, or short circuit conditions, the automatic bypass shall be
capable of sustaining overloads of 1000% of system capacity for sub cycle fault
clearing.
F. Modular: The automatic bypass switch shall be of a modular design and easily field
replaceable by certified technicians
2.8 DISPLAY AND CONTROLS
A. Control Logic: The UPS shall be controlled by two fully redundant, user-replaceable /
hot-swappable intelligence modules. These modules shall have separate, optically
isolated, communication paths to the power modules and the automatic bypass
contactor. Logic power for the control modules shall be derived from internal
regulated power supplies, each having a separate AC and DC input and output. The
communication of the control modules shall be of Inter IC Communication(IIC).
B. Display Unit: A microprocessor controlled display unit shall be located on a hinged
door in the front of the system. The display shall consist of an alphanumeric display
with backlight, an alarm LED, and a keypad consisting of pushbutton switches.