The device can be used to configure programs from 1.1.1.1 to 1.9.9.9.
4.1.5. Plug and Play
When a reactive energy regulator is installed, a series of parameters need to be configured in order to
ensure that it operates correctly. Some of these parameters might be difficult to discover, for example
such as the voltage phases or the correspondence between measured current and its voltage, as well
as the current transformer ratio. The Computer SMART III includes an automatic process which intelli-
gently works out necessary parameters such as:
Connection type: detects the connection type used from among the possible options: 3U.3C,
3U.1C and 2U.1C.
Phase: identifies the correspondence between the voltages and the currents connected, regard-
less of the connection type detected previously.
Number of stages installed and program: sequentially connects all the stages to work out how
many stages are installed and calculates the program, in other words the power ratio between the
capacitors.
C/K: calculates the ratio between the current transformer and the power of the smallest step.
4.1.6. Connection time (Ton) and reclosing time (Trec)
Connection time, Ton, defines the shortest possible time between changes in the status of the stages,
in other words, between connections and disconnections. Therefore, the configuration of this param-
eter has a direct impact on the compensation speed, in other words, on the capacity for monitoring
load changes. Setting a shorter connection time improves the power factor correction when the load
can change quickly.
However, a shorter Ton will lead to a higher number of connections per time unit, possibly shortening
the useful life of the associated components (contactors, capacitors). To assess the number of connec-
tions, Computer SMART III uses individual meters for each stage.
Reclosing time, Trec, is the shortest possible time between disconnecting a stage and reclosing it. This
time is necessary for the capacitor to discharge enough so that, when it is reclosed, it does not cause
overcurrents in the system.
4.1.7. THD and harmonics
Non-linear loads, such as those in rectifiers, inverters, speed drives, kilns, etc., absorb non-sinusoidal
periodic currents from the mains. These currents are made up of a fundamental component with a fre-
quency of 50 or 60 Hz, plus a series of overlapping currents, with frequencies that are multiples of the
fundamental frequency; these are defined as harmonics. The result is a deformation of the current and,
thus, of the voltage, which leads to a series of related side effects (conductor overload, circuit breakers
and machines, phase offsets, interferences in electronic units, RCCB trips, etc.).
The level of harmonics is usually measured with the total harmonic distortion rate (THD), which is
the ratio, usually as a %, of the RMS value of the harmonic content and the value of the fundamental
component.
26
Computer SMART III
Instruction Manual
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