Rockwell Automation 1608M MegaDySC User Manual, 800 - 2400 A - Manual (Page 19)

Rockwell Automation Publication 1608M-UM002A-EN-P - September 2013 19
Chapter
5
Operation
System Description Raw utility power enters and routes through the Automatic Bypass switchboard
to the load. In maintenance bypass mode the power bypasses the MegaDySC
cabinets and passes directly to the load. In this mode the load is unprotected from
voltage sags. In the Normal operation mode the MegaDySC cabinets are
energized and the power is directed through the MegaDySC, protecting the load.
See the following sections for MegaDySC and Automatic Bypass operation
details.
MegaDySC Operation A master control panel, located in the switchboard enclosure, constantly
monitors the line voltages and issues commands to the parallel-connected
MegaDySC sections. Each MegaDySC section contains three power electronics
modules (one module per phase). The modules act in parallel with the like phase
modules in the other MegaDySC sections, under command of the master
controls. Each module consists of a static switch and the sag-correcting
electronics. The parallel modules are series-connected to the input line, and
operate by adding the compensating voltage needed to restore the line to its
nominal output. When the utility line voltage is adequate, the static switch will
remain closed and no compensating voltage is added. When an insufficient line
voltage event occurs, the static switch opens and the sag-correcting electronics
(inverters) quickly add the balance of voltage necessary to regulate the load
voltage.
Thermal switches are included to activate fans if the cabinet temperature or other
internal temperatures exceed set limits.
A central touch screen display provides indication of the status of the MegaDySC
operation. After power is switched on, the green “OK” box will be displayed in
the upper left hand corner of the display, indicating that the output voltage is
within a normal range of 88.5% to 110% of nominal.
A red “FAULT” box is displayed in the upper left hand corner of the display
when an alarm condition is present on the MegaDySC. During this period sag
correction is inhibited and the MegaDySC will continue to bypass the utility
voltage directly to the load through the static bypass path.
An orange “Resetting” box is displayed when the previous alarm condition has
cleared. Sag correction will remain inhibited until the reset period has expired
(approximately 1 minute). A blue “SYSTEM OFFLINE” box is displayed
ATTENTION: Operation in Normal Mode requires that the maintenance bypass
circuit breaker (CBB) be open (OFF)-otherwise, voltage sag correction will be
defeated by the mechanical bypass.