Power Supply Theory of Operation
5-4 Theory of Operation TM-iX0A-0805
Non-Volatile Memory
Special algorithms have been employed to ensure the long-term validity of the data stored in
256 KB of flash memory. This memory is used to store all non-volatile data such as:
• Meter configuration (iConFig created meter Program)
• Billing data
• Load Profile data
• Status data
Power Supply
The power supply is a wide-range, switch-mode supply that is designed to operate from a
poly-phase supply. However, in the event of an outage on one or two phases, the power supply
continues operating. Some functionality may be inhibited under these circumstances, depending
on the option boards fitted to the meter and the service type/voltage. Refer to Appendix B:
Specifications for details of operating voltage ranges.
Demand Metering
Demand
Demand is calculated over an interval of time. Intervals can be configured but must be factors of
60 minutes (1, 2, 3, 5, 6, 10, 12, 15, 30, and 60). The Demand interval and subinterval lengths
(See “Sliding” below.) are configured using iConFig.
A new demand interval begins when the demand interval is changed or when entering or exiting
Test Mode. The number of minutes remaining in the current subinterval is available for display.
The EOI Annunciator temporarily illuminates at the end of each subinterval.
The meter calculates and stores the peak Demand for each energy value (kWh, kVARh, kVAh).
The meter also stores either the Cumulative or Continuously Cumulative Demand.
The meter can calculate Block Demand and Sliding (Rolling) Demand (kW, kVA, kVAR).
Block
NOTE:
To configure the meter for Block Demand, the subinterval is set to the same length of time
as the interval length.
Block Interval Demand is where the interval and subinterval are the same value. Dividing 60 by
the interval length and then multiplying the quotient by the measured Demand gives you Block
Demand.
EXAMPLE: If the interval length is 30 minutes and the measured energy is 100 kWh, then:
60 ⁄ Interval Length
*
Measured Energy = Block Demand
60 ⁄ 30
*
100 kWh = 200 kWh
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