Siemens siprotec 7SD5, Руководство пользователя

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2 Functions
376
7SD5 Manual
C53000-G1176-C169-1
Warning Tempera-
ture Levels By setting a thermal alarm stage
Θ ALARM
(address
4204
) an alarm can be provided
before the tripping temperature is reached, so that a trip can be avoided by preventive
load reduction or by switching over. The percentage is referred to the tripping temper-
ature rise.
The current overload alarm setpoint
I ALARM
(address
4205
) is stated as a factor of
the nominal device current and should be set equal to or slightly below the permissible
continuous current k ·
I
N
. It can also be used instead of the thermal alarm stage. In this
case, the thermal alarm stage is set to 100 % and thus practically ineffective.
Calculating the
Overtemperature The thermal replica is calculated individually for each phase. Address
4206 CALC.
METHOD
decides whether the highest of the three calculated temperatures (
Θ max
) or
their arithmetic average (
Average Θ
) or the temperature calculated from the phase
with maximum current (
Θ at Imax
) should be decisive for the thermal alarm and trip-
ping stage.
Since an overload usually occurs in a balanced way, this setting is of minor impor-
tance. If unbalanced overloads are to be expected, however, these options lead to dif-
ferent results.
Averaging should only be used if a rapid thermal equilibrium is possible in the protect-
ed object, e.g. with belted cables. If the three phases are, however, more or less ther-
mally isolated (e.g. single conductor cables or overhead lines), one of the maximum
settings should be chosen at any rate.
2.21.3 Settings
The table indicates region-specific presettings. Column C (configuration) indicates the
corresponding secondary nominal current of the current transformer.
2.21.4 Information List
Addr. Parameter C Setting Options Default Setting Comments
4201 Ther. OVERLOAD OFF
ON
Alarm Only OFF Thermal overload protec-
tion
4202 K-FACTOR 0.10 .. 4.00 1.10 K-Factor
4203 TIME CONSTANT 1.0 .. 999.9 min 100.0 min Time Constant
4204
Θ
ALARM 50 .. 100 % 90 % Thermal Alarm Stage
4205 I ALARM 1A 0.10 .. 4.00 A 1.00 A Current Overload Alarm
Setpoint
5A 0.50 .. 20.00 A 5.00 A
4206 CALC. METHOD
Θ
max
Average
Θ
Θ
at Imax
Θ
max Method of Acquiring Tem-
perature
No. Information Type of In-
formation
Comments
1503 >BLK ThOverload SP >BLOCK Thermal Overload Protection
1511 Th.Overload OFF OUT Thermal Overload Protection OFF
1512 Th.Overload BLK OUT Thermal Overload Protection BLOCKED
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