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This moment is also assumed to be a time base for following volt/ampere demand
interval measurements.
2. Starting immediately, the first shorter demand interval is not considered for the demand
measurements, and used exclusively for starting synchronization, for either internal or
external time base source. Readings for demands that refer to block interval demand
techniques, are not updated until the end of the second demand interval, except for the
accumulated demand. For demands that refer to sliding window techniques, readings
are not updated until the end of the first sliding window billing period, without taking into
consideration the starting demand interval.
Until the end of the first demand interval, the accumulated demand readings will be
lower than those calculated over the entire demand interval. Predicted demand
readings (in the event that the demand window comprises a solitary demand interval)
will give prediction at the later time than the present shorter interval will be terminated.
3. When the external synchronization source is used, for the first time after changing the
demand setup and after power up, the demand interval will have a maximum value
allowed of one hour. Until the second synchronization pulse, the accumulated demand
readings will be incorrect, and predicted demand readings will provide a prediction at
the later or shorter time.
4.3.8 Demand Interval Pulse
The PM295 can provide a timing pulse indicating the beginning of new demand
interval for consumer use. It can be used as synchronous time reference for other
instruments that have no internal demand interval synchronization.
The beginning of the demand interval is also asserted in the instrument as an internal
event that can be used to trigger a setpoint (e.g., to synchronize self-readings with
demand interval, or to operate relay output in customized order).
4.4 Energy Measurements
4.4.1 Measurement Modes
Energy parameters are calculated from the corresponding instantaneous total powers
for all three phases. The PM295 provides energy measurements for active (kWh),
reactive (kvarh) and apparent (kVAh) energy. For active and reactive energy , four
measurement modes are available:
• imported (positive) energy - consumed kWh/inductive kvarh. Readings are
represented by a positive number
• exported (negative) energy - returned (reversed) kWh/capacitive kvarh.
Readings are represented by a negative number
Operation Techniques
63
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