Siemens siprotec 7SD5 User Manual

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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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English