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7-14

Event Options

Voltage and

Current

channels to plot

A time plot is a graph of the value of one parameter and channel over time. The

PowerVisa is able to display time plots for individual Voltage and Current channels

(Va, Vb, Vc, Vd, Ia, Ib, Ic, Id) or phase-to-phase Voltage channels (Vab, Vbc, Vca),

depending on the available channels for Voltage and the selected circuit type.

RMS trigger

parameters

RMS variation is the most common type of disturbance and is identified as a specific

type of event by IEEE and IEC. Event characterization implemented in PowerVisa

adheres to the IEEE 1159 and IEC 61000-4-30 Class A standards (Refer to Appendix F

Event Classification). RMS values are updated at half-cycle rates, calculated over one

cycle and compared against limits on a cycle-by-cycle basis. The high and low limits

can be enabled and programmed individually for each phase and phase-to-phase value.

The following parameters are required to define how an rms variation is triggered:

Very Low limit

Low limit

High Limit

Cycles in range to end event

As per IEEE and IEC standards for multi-phase systems, the beginning of the voltage

rms event occurs when any phase voltage goes outside the limits, and ends when all of

the phases are within limits for an end-event number of cycles specified. This is only

true for voltage, not current.

In addition, rms variations can have three stages of averaging or chart rates, which is

particularly useful for long duration events to save memory in exchange for reduced

resolution. This mode begins if the rms value remains out of limits for longer than the

post-start number of cycles that were programmed.

Refer to Chapter 6 Advanced Setup Options for more information on rms variation

limits.

What is

displayed on a

time plot?

A time plot consists of the timed and threshold waveforms for the parameter on display.

The instrument provides users Options to change and/or add parameters/channels to

plot.

Channels

Voltage: A, B, C, D, A-B, B-C, C-A

Current: A, B, C, D

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