Changing The G4 Ex Clock; Clock Change Not Crossing An Hour Boundary; Forward Clock Change Crossing An Hourly Boundary; Backward Clock Change Crossing An Hourly Boundary - ABB XSeries G4 6200 User Manual

4.6

Changing the G4 EX Clock

When any measurement applications are instantiated on the G4 EX, changing the
clock could affect the time when log period entries are made. To protect the
integrity of the accounting audit trails, the G4 EX handles these types of clock
changes as follows:

4.6.1 Clock Change Not Crossing an Hour Boundary

When the next log period entry is made, the clock is not altered.
Example: If the present time is 4:14 pm and the clock is changed to 4:05 pm of
the same day, the daily flow record is the same. Entry reflects averages
accumulated over a 70 minute time period (15 minutes plus 55 minutes).

4.6.2 Forward Clock Change Crossing an Hourly Boundary

Forces a log period entry for part of the hour that has accumulated since the last
hourly entry. The G4 EX then advances to the newly defined data flow record
boundary and begins maintaining the balance of the day's data in a newly defined
boundary.
Example: If the present time is 4:55 pm and the clock is changed to 5:05 pm of
the same day, the entry reflects only a 55 minute average accumulation. A new
flow record is then written. This period is also based on a 55 minute accumulation.

4.6.3 Backward Clock Change Crossing an Hourly Boundary

Hourly entry is made for part of the hour that has accumulated since making the
last hourly entry. This is the same as a Forward Clock Change Crossing an Hourly
Boundary. The G4 EX advances to a new day's data flow record and maintains
the balance of the day's data in a new record.
Example: If the present time is 5:05 pm and the clock is changed to 4:55 pm of
the same day, the log period entry reflects only a five minute average
accumulation. A new flow record is then written. This log period is based on a 60
minute accumulation.
4.7

Replacing the G4 EX battery Pack

This chapter presents the procedures for removal and installation of the G4 EX
battery pack that is located within the 6270 OEU. To access the battery pack,
open the door (see Figure 4–3). The battery pack is located in the upper portion of
the chamber.
Page 4–6
A backward clock change uses two records to maintain data
integrity. This assures that previously recorded data is not
overwritten.
If it is necessary to make small backward time changes of
less than one (1) hour, the user should wait until the current
hour has progressed far enough to make a change that does
not cross an hour boundary.
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