GE Power Management
745 Transformer Management Relay
10-17
10 COMMISSIONING
10.6 PROTECTION SCHEMES
10
1.
To measure the slope, connect current signals to the relay as shown in the figure below:
Figure 10–6: CURRENT SIGNAL CONNECTIONS
2.
If
I
1
= 1.5
×
CT and
I
2
= 0, the element is operated as all the current appears as a differential current.
3.
The slope is calculated from the values of
I
differential
and
I
restraint
as shown below:
4.
Slowly increase
I
2
. As
I
2
is increased, the element will reset when the differential current drops below the
minimum pickup.
5.
As
I
2
continues to increase, the element operates again when both the initial slope and the minimum
pickup conditions are satisfied. Calculate the initial slope 1 value at this point.
6.
As
I
2
increases further, the element may reset again, depending on the setting of the slope kneepoint. This
is caused by the current values moving into the slope 2 region.
7.
Continue increasing
I
2
until the element operates again. Compute the slope 2 value at this point.
g) SLOPE KNEEPOINT
1.
To measure the approximate location of the kneepoint, follow the procedure above, setting
I
1
at a value
equal to the kneepoint. Gradually increase
I
2
until the element resets. Calculate the first slope at this point.
The value thus obtained should be equal to the initial slope setting. Increase
I
2
until the element operates
again. Calculate the slope at this point – it should be equal to the final slope. If the kneepoint is much differ-
ent than the selected value of
I
1
, the two values of slope will be the same.
2.
For an accurate measurement of the kneepoint, select a value of
I
1
just above the kneepoint value.
3.
Increase
I
2
until the element resets. Calculate the slope – the value should be equal to the initial slope
value.
4.
Increase
I
1
by a small amount, say 10%, and adjust
I
2
until a new operating point is obtained. Calculate the
slope. Repeat until the slope value equals the final slope. The kneepoint value is the value of the restraint
current at which the slope changed in value.
Keep in mind the effects of auto-configuration on the magnitude of the current signal fed to
the differential elements when conducting the slope kneepoint test.
%slope
I
differential
I
restraint
--------------------------
100%
×
=
NOTE
Содержание 745 TRANSFORMER MANAGEMENT RELAY
Страница 30: ...2 8 745 Transformer Management Relay GE Power Management 2 3 SECURITY 2 GETTING STARTED 2 ...
Страница 150: ...5 100 745 Transformer Management Relay GE Power Management 5 10 INVERSE VOLTS PER HERTZ CURVES 5 SETPOINTS 5 ...
Страница 210: ...7 36 745 Transformer Management Relay GE Power Management 7 2 BLOCK DIAGRAMS 7 SCHEME LOGIC 7 ...
Страница 322: ...9 12 745 Transformer Management Relay GE Power Management 9 3 USING 745PC 9 745 PC SOFTWARE 9 ...
Страница 392: ...11 24 745 Transformer Management Relay GE Power Management 11 1 COMMISSIONING SUMMARY 11 SETPOINT TABLES 11 ...
Страница 396: ...A 4 745 Transformer Management Relay GE Power Management A 1 FIGURES AND TABLES APPENDIXA A ...
Страница 398: ...B 2 745 Transformer Management Relay GE Power Management B 1 EU DECLARATION OF CONFORMITY APPENDIXB B ...
Страница 400: ...C 2 745 Transformer Management Relay GE Power Management C 1 WARRANTY INFORMATION APPENDIXC C ...
Страница 406: ...vi 745 Transformer Management Relay GE Power Management ...
Страница 407: ...GE Power Management 745 Transformer Management Relay NOTES ...