User's Manual

Operation: C1SD, C1ST, and C1SL Versions
CENTRON Meter Technical Reference Guide 5-25
Option Boards
CENTRON R300CD Operation
The R300CD option provides two RF transmission messages for energy and
demand readings. It is programmed with two unit ID’s, one for identifying energy
(kWh) related Standard Consumption Messages (SCMs), and one for demand
(kW). The even ERT ID number will always correspond to the energy value, and
the odd ID will always correspond to the demand value. Only the even ID number
will be displayed on the meter nameplate, and the demand ID will be the next
sequential number.
The R300CD transmits two different types of SCMs representing energy and
demand. This is the only mode of operation used by the R300CD. R300CD option
boards must be installed in a Time-of-Use (TOU) equipped (battery and full
calendar clock capability) CENTRON. The R300CD will interrogate the TOU
module once per minute and read the self read kWh and self read kW values. These
values will typically change only once per billing period.
The kWh value broadcast in its SCM shall have six (6) significant digits. The
R300CD converts the floating point BCD kW reading extracted from the
CENTRON self read register to a fixed implied decimal with two digits of
resolution to the right of the decimal point (.01 kW). The maximum kW measured
is therefore restricted to 9999.99 kW.
Figure 5.9 on page 5-26 is a block diagram of R300CD hardware. R300CD hardware
consists of two option boards: a control section and RF section. The control
section communicates to the TOU module at rate of once per minute using the
expansion port on the TOU module. The communication speed is fixed at 2400
baud in the control section and uses the SCS protocol. In each of the two SCMs
described, the respective parameter reported is converted to a binary format for
the RF transmission. No register information is saved in the R300CD option
boards. In the instance of a power outage, the option board will update the kW and
kWh values from the self read register upon power restoration.
The R300CD features the SchlumbergerSema patented method of tamper detection
that senses both meter removal and inversion. The removal tamper (RTPR)
increments a counter each time the meter is abruptly removed from a live meter
socket. The tamper counter utilizes a tilt switch to detect when the meter is
removed from the meter socket. The inversion tamper (ITPR) increments a
separate counter each time the meter senses an inversion. The inversion tamper
will be incremented when an inverted status is detected through a closed tilt
switch upon power up. Each of these tamper indications are then transmitted
through the radio frequency transmission.