POWERSCOPE PROGRAM
MTS-3000 SERIES OPERATION AND REFERENCE MANUAL B-9
CU M004 01A .
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Figure B.11
The absolute value of the impedances (Zab, Zbc, Zca, Zag, Zbg, and Zcg) are displayed above the
impedance window in magnitude and angle format. If the currents are zero, the impedance value will be
displayed as infinite.
Examples of interesting tests presented with the impedance window include:
1. A reach test performed by slow ramping of current and voltage can dynamically show the apparent
impedance approaching and entering the region of protection. When the relay operates, the impedance
should go to infinity .
2. When testing Zone 2 and 3 elements with a .5 second or higher timers, a dynamic test will show the fault
impedance of the active element entering the region of protection, and then leaving when the relay
operates.
3. The effect of prefault load on apparent impedances also can be readily demonstrated. If sufficient
prefault currents are set, the apparent impedance can be seen outside the region of protection. High
prefault load can cause more than one element to enter the region of protection.
4. A manual test of MTA by ramping phase, within the impedance circle, can dynamically show the
impedance approaching the characteristic boundary on the left and right sides.
B.4.2 Defining & Displaying Theoretical Relay Characteristics
Theoretical mho and quadrilaterial characteristics can be defined in the dialog window which appears when
Edit|Properties is selected (with the impedance window active). Multiple mho characteristics can be defined
using the “Add” button.