For medium voltage systems it is common to use two or three autoreclose shots, and, for specific applications, four shots. Using four shots, final dead time can be set for a time long enough to allow thunderstorms to stop before definitive final reclose. This scheme prevents unnecessary lockout caused by consecutive transient faults.
The ACX controller supports 32 MB of Flash memory; 12 MB are
reserved for the OMS database and the rest is reserved for the
operating system (Boot Loader and Application).
Note: When using the Backup to Flash command, only the OMS
database is loaded into the Flash memory.
Advantages of Having Flash Memory
Initially it may seem redundant to include a flash memory along with
battery-backed memory to hold application data. However, it is this
redundancy that makes its addition attractive.
Although it is unlikely that the battery will fail or that the data in
memory will become corrupted, there is an extra layer of protection for
your configuration data if you can periodically lock it into flash.
Flash Files
Periodically, newer versions of the operating system are released. You
can find and download the latest version from the Schneider Electric
Technical Support web site. These new versions consist of one or more
“flash files”. Workstation software (CyberStation 1.8 or higher)
includes provisions to upload these flash files directly to the controller.
Limitations of Flash Memory
Flash memory circuits are rated for a limited number of write
operations (minimum of 10,000 to an average expected lifetime of
100,000). In the ACX controller, flash memory is used for storing
completed configurations and a snapshot of data at a particular time.
When used in this manner, the memory should last the lifetime of the
product. To give you an idea of how many operations are available, see
the following table.
