Bitronics M651, User Manual

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ML0039 November 14, 2013 Copyright 2013 Bitronics, LLC
Demands are initialized to the minimum and maximum values recalled from
non-volatile memory. Upon a demand reset, the Maximum and Minimum Demands
are set equal to the Present Total Watt, VAR, and VA Demand values. A demand
reset does not change the value of the Present Total Watt, VAR, and VA Demands.
6.10.4 Demand Resets
The demand values are reset in 3 groups: current, voltage, and power. This can be
accomplished via the front display or from a web browser.
6.10.5 Demand Interval
The M651 uses 900 seconds (15 minutes) as the default demand interval for current.
The default for average volts and average power measurements is 60 seconds. Three
separate, independent demand intervals may be set for current, voltage, and power.
The range of demand intervals is 10 to 9999 seconds. These settings can be
accomplished by using the front display or web server setup.
6.11 Harmonic Measurements
All harmonic and harmonic related measurements are calculated every 100 ms. In
the following sections, Harmonic 0 indicates DC, Harmonic 1 indicates the
fundamental, and Harmonic N is the nth multiple of the fundamental.
6.11.1 Voltage Distortion (THD)
Voltage Harmonic Distortion is measured by phase in
several different ways. The equation for Total Harmonic
Distortion (THD) is given in Equation 1. Note the
denominator is the fundamental magnitude.
6.11.2 Current Distortion (THD and TDD)
Current Harmonic Distortion is measured by phase in
several different ways. The first method is Total Harmonic
Distortion (THD). The equation for THD is given in Equation
2. Note the denominator is the fundamental magnitude.
63
2
2
1
% 100%
h
h
I
THD
I
=
= ×
∑
63
2
2
1
% 100%
h
h
V
THD
V
=
= ×
∑
Equation
1
- Voltage THD
Equation
2
- Current THD