50Gs/51Gs Sensitive Earth Fault - Siemens 7SR51 Device Manual

Curve
IEC-NI
IEC-VI
IEC-EI
IEC-LTI
Apply current in the following sequence, a) 2 times setting for a time to ensure element operation, b) Zero
current for the reset time above (xTm), c) 2 times setting for a time to ensure element operation. Check that
the second operation (c) is similar to the first (a) and in line with the expected operate time for the element at
this current level. Repeat the test with the reset time (b) reduced to 50 % of the previous value. Ensure that
the second operate time (c) is 50 % of the first (a) operate time.
Operate Time
(expected)

50GS/51GS Sensitive Earth Fault

9.9.14
Other protection functions may overlap with these functions during testing, it may be useful to disable some
functions to avoid ambiguity. Calculated EF, Measured EF, Sensitive EF & Restricted EF protec-
tions can be Enabled/Disabled individually or as groups in the Function Config menu.
Sensitive EF (GS) elements can be separated from Calculated EF by secondary injection of current
through the CT4 input circuit only.
If any of these elements are defined as directional the correct residual voltage phase direction will be required
to produce correct operation of the 67GS element for an operation of those elements.
The 67GS elements will normally operate on the residual current through the CT4 input but can be set to
operate on only the real (wattmetric) component of this current by setting 67GS I
option is selected, the residual current and voltage should be set in anti-phase during testing to so that the
applied current is purely real and can be measured directly.
If 67GS Wattmetric is set to Enabled, the residual real power must also exceed the 67GS Wattmetric
Power setting to permit any directional 50GS element operation
Directional Polarity
See 10 Technical Data
If 67GS Wattmetric is set to Enabled, the residual real power must also exceed the 67GS Wattmetric
Power setting to permit GS operation. As the directional boundary is approached, the wattmetric current, will
by definition reduce towards zero. It is therefore necessary to increase the residual current or to temporarily
disable the Wattmetric function to allow the directional boundary to be tested.
If the 67GS Compensated Network setting is set to Enabled, the directional boundaries will be extended
to MTA + 87° and MTA - 87°.
MTA
Pick-up
MTA -85
GS
Definite Time Overcurrent (50GS)
If DTL setting is small, gradually increase current until element operates.
If DTL is large apply 0.9 times setting, check for no operation, apply 1.1 times setting, check operation.
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
Reset Time Operate Time
(calculated) (measured)
First test (c)
for testing details.
Forward
Lag (point C) Lead (point A)
Drop-off Pick-up
MTA +85
Fully Operated to Reset with Zero Current Applied
& Tm = 1 (s)
9.7
43.2
58.2
80
50 % Reset Time 50 % Operate
(calculated) Time (calcu-
lated)
Lead (point B)
Drop-off Pick-up Drop-off
MTA -85
Functional Tests
9.9 Protection Functional Tests
50 % Operate
Time (meas-
ured)
Second Test (c)
Select to I Real. If this
res res
Reverse
Lag (point D)
Pick-up Drop-off
MTA -85
479