Arc Flash Hazard Analysis in Coordination Focus

You can perform arc flash hazard analysis in the Coordination focus by selecting the desired bus to fault and clicking Arc Flash. For this application, you must have the arc flash hazard feature enabled in your software.

Insert SC Tick Mark

To insert user-defined short circuit tick marks on the TCC plot, click Insert SC Tick Mark on the TCC ribbon.

Figure 1: Insert SC Tick Mark Dialog Box

Current: You can select the appearance of the symbol that represents the short circuit current type.

• A Symmetrical current appears as an arrow with unfilled head.
• An Asymmetrical current appears as an arrow with solidly filled head as shown in the figure below.

These are default settings and can be edited by formatting tick marks. You can also save the format as new default tick marks.

Figure 2: Short Circuit Tick Marks

Fault: Selection of fault type affects the time coordinates of the tick mark. The choices are Momentary for half cycle, Interrupting for 5 cycles, and 30-cycle. The short circuit tick mark may be dragged vertically within a limited distance.

Short Circuit Current: Enter the short circuit current value in kilo amps The tick mark is placed on the TCC plot at the specified current value times the ratio of short circuit reference voltage to TCC plot reference voltage.

Reference Voltage: Enter the reference voltage at the short circuit point in kilo volts. The tick mark is placed on the TCC plot at the specified current value times the ratio of short circuit reference voltage to the TCC Scale reference voltage.

Formatting SC Tick Marks

To format a short circuit tick mark to the desired shape, color and size, click the arrow below Format TCC and select SC Tick Mark from the list.

Figure 3: Format SC Tick Mark

You can also set the default format for tick marks by clicking the Default button.

Arcing Current Tick Mark

Arcing current tick mark represents the current through a protective device for an arcing fault (arc flash). You can insert an arcing current tick mark after faulting a bus on the one-line by right-clicking on the TCC curve and clicking Insert Arcing Current Tick Mark.

Note: This option is available only if your program has the Arc Flash feature.

LV Breaker Series Coordination Tick Mark

As per manufacturer’s publications, LV Breakers in series can be selectively coordinated in the instantaneous trip region up to a certain short circuit level although the TCC plot may indicate otherwise. If two breakers plotted on the TCC have series coordination data specified in the library, then a tick mark appears to indicate the maximum short circuit current up to which coordination is possible. If a breaker style is changed in a TCC plot, the TCC needs to be plotted again to get the new series coordination tick mark.

Figure 4: Series Coordination Tick Mark

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