Phase Directional Polarity Check - Siemens 7SR224 Technical Manual

current or voltage. The resulting composite characteristic may be tested by enabling all of the relevant applicable
elements or the element operations can be separated or disabled and tested individually.
All relay settings should be checked before testing begins. It is recommended that the relay settings are extracted
from the relay using Reydisp Evolution software and a copy of these settings is stored for reference during and
after testing. It may be necessary to disable some protection functions during the testing of other functions to
allow unambiguous results to be obtained.
Care must be taken to reset or re-enable any settings that have been temporarily altered during the testing before
the relay can be put into service. At the end of testing the relay settings should be compared to the file extracted
at the start to ensure that errors have not been introduced.
An example 'Test Sheet' summary document is included at the end of this Guide.
2.1

Phase Directional Polarity Check

If the relay has Directional Overcurrent elements, the common direction polarising can be checked independently
from the individual overcurrent elements and their settings.
In the INSTRUMENTS MODE display, indication is provided in the DIRECTIONAL METERS menu which displays
current direction under P/F Dir as forward or reverse based on the output states of the directional elements, i.e.
whether they see forward current, reverse current or neither for each pole with respect to the 67 Char Angle
setting in the Phase Overcurrent menu. This display and the equivalent Measured and Calculated Earth Fault
direction meters can be used as an aid to commissioning testing.
The tests below show directional polarising for convention A-B-C positive phase sequence. In the unusual case of
A-C-B positive phase sequence applications, the polarising voltages are inverted to suit the actual conditions for
such a system as shown below.
1. Check the direction of each pole in turn by connecting to the appropriate terminals. The table below shows
the polarising quantity for each pole.
Connections for Directional Polarity
Overcurrent pole
Phase A
Phase B
Phase C
Connections for non standard A-C-B positive phase sequence applications.
Overcurrent pole
Phase A
Phase B
Phase C
2. Inject single phase rated current and apply single phase-phase rated voltage at the Char Angle (MTA) phase
angle setting, to each phase in turn. For each pole, monitor the directional display in the instrument menu
and check that indication of forward current (FWD) is displayed. To achieve the required forward
Characteristic Angle, the phase angle of the current should be greater than that of the polarising voltage by
the angle setting.
3. Repeat all of the above with the current connections reversed. Indication should now be given of reverse
(REV) current flow.
Phase
Forward
Reverse
4. Apply balanced 3 phase rated voltage and current with Vbc (or Vcb for non standard A-C-B system
applications) voltage as a 0deg reference and Ia at the characteristic angle. Increase current phase angle
until the 'Fwd' indication is extinguished. Record this angle in the table below (Forward lead DO). Continue
©2010 Siemens Protection Devices Limited
7SR224 Argus Commissioning & Maintenance Guide
V
BC
V
CA
V
AB
V
CB
V
AC
V
BA
A
FWD FWD
REV REV
Polarising voltage
Polarising voltage
B C
FWD
REV
Chapter 6 Page 14 of 73