Novatech Bitronics M87X Series, Руководство пользователя

Страница: 54 / 184

ML0021 August 15, 2018
38
Copyright 2018 Bitronics, LLC
the traditional value of T is 15 minutes, although the M87x can accommodate other
demand intervals (Section 4.7.7).
The M87x generates a demand value using modern microprocessor technology in place of
heating and cooling circuits, it is therefore much more accurate and repeatable over a wide
range of input values. In operation, the M87x continuously samples the basic measured
quantities, and digitally integrates the samples with a time constant T to obtain the demand
value. The calculated demand value is continuously checked against the previous
maximum and minimum demand values. This process continues indefinitely, until the
demand is reset or until the meter is reset (or power removed and reapplied). The demand
reset and power-up algorithms are different for each measurement. These routines are
further described in following paragraphs. The maximum and minimum demand values
are stored in non-volatile memory on the Host Processor module.
NOTE:
Changing VT or CT ratios does NOT reset demand measurements to zero.
Demand Quantity Phase Reference Function
Amperes (1 & 2) Phase, Neutral, Residual Present, Max
Fundamental Amperes Phase, Neutral, Residual Present, Max
Volts (Bus 1 & 2) Phase - Neutral, Phase - Phase Present, Max, Min
Total Watts (1 & 2) Present, Max, Min
Total VARs (1 & 2) Present, Max, Min
Total VAs (1 & 2) Present, Max, Min
THD Volts (Bus 1 & 2) Phase - Neutral, Phase - Phase Present, Max
TDD Amperes (1 & 2) Phase, Neutral, Residual Present, Max
4.7.1 Ampere and Fundamental Ampere Demand
Present Ampere Demands are calculated via the instantaneous measurement data used to
calculate the per-phase Amperes.
Upon power-up, all Present Ampere Demands are reset to zero. Maximum Ampere
Demands are initialized to the maximum values recalled from non-volatile memory. Upon
Ampere Demand Reset, all per-phase Present and Maximum Ampere Demands are set to
zero. When Ampere Demands are reset, Fundamental Current Demands are also reset.
4.7.2 Volt Demand
Present Volt Demands are calculated via the instantaneous measurement data used to
calculate the per-phase Volts. Upon power-up all Present Volt Demands are reset to zero.
The Maximum Volt Demands and Minimum Volt Demands are initialized to the minimum
and maximum values recalled from non-volatile memory. In order to prevent the recording
of false minimums a new Minimum Volt Demand will not be stored unless two criteria are
met. First, the instantaneous voltage for that particular phase must be greater than 20V
rms
(secondary). Second, the Present Demand for that particular phase must have dipped
(Present Demand value must be less then previous Present Demand value). Upon
Voltage Demand Reset, all per-phase Maximum Voltage Demands are set to zero.
Minimum Voltage Demands are set to full-scale.