Section 12 Checking the directionality
12.1 Overview
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Before starting this process, all individual devices that are involved in the fault clearance process of
the protected object must have been individually tested and must be set in operation. The circuit
breaker must be ready for an open-close-open cycle.
The directional test is performed when the protected object is energized and a certain amount of load
current is available. It is also necessary to know the flow of the load current (import or export, i.e.
forward or reverse) by help of the indication from an external instrument (energy-meter, or SCADA
information).
The design of the test procedure depends on the type of protection function to be tested. Some items
that can be used as guidelines are the following.
12.2 Testing the directionality of the distance protection
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The test is performed by looking at the information given by the High speed distance protection
ZMFPDIS, ZMFCPDIS or the directional function ZDRDIR or ZDMRDIR whichever is used.
Procedure:
1. Make sure that all control and protection functions that belong to the object that are going to be
energized have been tested and are set to be in operation
2. Make sure that the primary load current fulfills the following conditions (by using an external
equipment):
• The magnitude of the primary load current must be higher than the minimum operating
current set for the directional elements in the IED. In case of default settings this means:
• load current > 5% of base current
• Otherwise the settings IMinOpPE and IMinOpPP for ZDRDIR or ZDMRDIR are
available under the HMI menu: Main menu /Settings /IED Settings /Impedance
protection /DirectionalImpedance
The primary load impedance must have an angle (PHI) between the setting angles for the
directional lines. In case of default settings this means:
• for forward (exported) load: -15 deg < PHI < 115 deg
• for reverse (imported) load: 165 deg < PHI < 295 deg
The settings for forward load: - ArgDir < PHI < ArgNegRes and the settings for reverse load: 180
deg - ArgDir < PHI < 180 deg + ArgNegRes included in the directional functions ZDRDIR or
ZDMRDIR are available under the HMI menu:
• Main menu /Settings /IED Settings /Impedance protection /DirectionalImpedance
3. The directionality of the load current is shown by the High speed distance protection ZMFPDIS
or ZMFCPDIS under the HMI menu: Main menu /Test /Function status /Impedance
protection /HighSpeedDistance or by the directional function ZDRDIR or ZDMRDIR and it is
available under the HMI menu: Main menu /Test /Function status /Impedance protection /
DirectionalImpedance
The following will be shown if the load current flows in forward (exporting) direction:
• L1Dir = Forward
• L2Dir = Forward
• L3Dir = Forward
The following will be shown if the load current flows in the reverse direction (importing):
1MRK 505 378-UEN Rev. K Section 12
Checking the directionality
Line differential protection RED670 255
Commissioning manual
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