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6 - 29
Siemens AG ⋅ January 1999
It is important for all tests that the appropriate indicaĆ
tions are given by the LEDs and by the signal relays
for remote signaling.
Following tests which initiate indications via the
LEDs, these should be reset via the reset pushbutton
on the front panel (button N) and via binary input for
remote resetting (if this is marshalled). Once via biĆ
nary input and once via pushbutton is sufficient. After
the reset functions have been checked, the displays
need not be reset after every test because they are
reset automatically with every protection activation
and replaced by the new indication state.
6.6.2 Checking the line differential protection
To test the differential protection function, it must be
activated, i.e. DIFFPROTECTION (addr. 10 DIFPRO)
to The pilot wire monitoring must be switched
off (addr. 1601 11 PW.MON = ).
The pilot wire connections can be short-circuited for
the test.
When testing a pair of devices the pilot wires of both
devices are connected to each other with swapped
polarity. Both devices must be connected to auxiliary
supply voltage. In this case the second device can run
without a test current (corresponds to the simulation
of a single-end fed line short-circuit), or the test curĆ
rent is fed through both devices, in phase (internal
short-circuit) or reversed phase (external short-cirĆ
cuit).
When evaluating the currents, note that the current
processed by the differential protection is dependent
on the connection of the summation transformer and
the parameters 01 IN Ln and 01 IW PRI. For the test
current injection, an "ideal" current source must be
used.
The following applies:
I
P
=I
M
N
MW
N
Par
with
I
P
- test current,
I
M
- measuring current, processed by the device,
N
MW
- transformation factor summation transformer,
N
Par
- transformation factor of the parameters.
Symmetrical three-phase test current and standard
connection of the summation transformer according
to Figure 5.3 N
MW
= 1; at default setting of the deĆ
vice N
Par
= 1 also.
For testing with single-phase current, table 6.1 speciĆ
fies the factors N
MW
depending on the winding on
which the current is injected.
Table 6.1 Current factors for summation
transformers
Winding (facĆ
tor)
Summation
transformer
connection
bridged termiĆ
nals
N
MW
1 A-F B-E 1.73
2 C-H D-G 0.87
3 L-M - 0.58
6
(all in series)
A-M B-C
D-E
F-G
H-L
0.29
The parameter factor results from
N
Par
Ă +Ă
I
NĂline
I
NĂtransformer
with
I
N line
- primary rated current of the line, as
parameterized under addr. 01 NLn,
I
N transformer
-primary rated current of the current
transformers, as parameterized under
addr. 01 WPRI.
Example:
Rated current of the device 1 A; parameter 10-Dif>
= 0.5
n
=
M
; current factor for summation transforĆ
mer N
MW
= 0.87 (Table 6.1 - Summation transformer
connection C-H, bridged terminals D-G); rated curĆ
rent of the line (parameter 01 IN Ln) - 500 A; primary
rated current of the main current transformer (paraĆ
meter 01 IW PRI) - 1000 A.
Test current I
p
at the summation transformer input
terminal C-H for testing the parameters:
p
+
M
Ă
MW
@
Ă + 0, 5 @ 0, 87 @
500
1000
+ 0, 2175Ă A
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