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1MRK 504 160-UEN -
Section 11
11.1
11.2
Transformer protection RET650 2.1 IEC
Commissioning manual
Checking the directionality
Overview
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.
Testing the directionality of the distance protection
The test is performed by looking at the information given by the Distance protection
ZMFPDIS function.
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
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
3.
The directionality of the load current is shown by the Distance protection
ZMFPDIS under the HMI menu: Main menu/Test/Function status/Impedance
protection/Distance
Section 11
Checking the directionality
101
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