User's Manual

Operation: C1SD, C1ST, and C1SL Versions
5-22 CENTRON Meter Technical Reference Guide
Present Interval Demand
The present interval demand value is the demand value at the present time
normalized to the demand interval length. Present demand reports the calculated
demand value as it increases from the start of a demand interval to the end of the
interval. For rolling demand intervals, present demand reports the calculated
demand value from the present subinterval as it is accumulating with the previous
set of subintervals.
Power Procedures
Applying Power
Personality Modules are powered directly from line voltage via the board-to-board
connector. These modules are energized when AC power is present. During power
outages, the permanently installed lithium battery runs the clock circuit on C1ST
and C1SL versions. The battery normally lasts for the life of the meter. However, in
the unlikely event of a low battery notification, the battery or Register Module may
need to be replaced.
Battery Life (Load Profile & TOU)
The CENTRON TOU and Load Profile personality modules have a permanently
soldered battery present on their circuit boards. This battery powers the clock
when power is disconnected from the meter. The module program is transferred to
EEPROM for recall when power is restored.
The battery life is longer for the CENTRON TOU and Load Profile modules than
the J5 200 Series electromechanical hybrid meters. The capacity of the new battery
is larger than equivalent older products, and the current consumption is reduced
with new electronics technology.
In the process of determining this factor, battery life calculations are made
assuming worst case conditions for both the battery capacity (at the lowest end of
the manufacturer published initial limit) and the meter current consumption
(assuming all the components are at the maximum side of their published
tolerance).
The battery is also assumed to be operating at a self-discharge rate equal to a
constant average temperature of 160°F. At this temperature the battery will lose 2%
of its capacity per year (see dashed curve in Figure 5.8).
The design assumes that a significantly higher average temperature would increase
the self-discharge and that a lower average temperature would lower the self-
discharge.
The battery technology used is Lithium Thionyl Chloride. The battery life
calculations use a safety factor that takes into account the increase in battery
internal resistance as it approaches its end of life. This increase in internal
resistance occurs before the battery voltage starts decreasing under open circuit
conditions. This 80% limit for the maximum capacity usage is factored into the
design.
DO NOT REMOVE THE ELECTRONICS’ HOUSING WHILE THE METER IS POWERED. LINE
LEVEL VOLTAGES ARE PRESENT ON THE CIRCUIT BOARD. FAILURE TO FOLLOW THIS
PROCEDURE COULD RESULT IN SERIOUS PERSONAL INJURY OR DEATH. THE
WARNING LABEL SHOULD ALWAYS BE VISIBLE ON THE HOUSING.