Application And Setting Notes - Siemens 7SJ82 Manual

Measured Value
(_:13591:321) V/f th.
Cooling Time
If the value drops below the threshold ((_:13591:3) Threshold), tripping of the thermal characteristic
curve (dependent characteristic curve) is reverted. However, the parameterized cooling time (Cooling time
therm.replica) reduces the thermal storage (counter content) to 0. This parameter is defined as time. It is
required by the thermal replica in order to cool down from 100 % to 0 %.
Resetting the Thermal Map
The binary input indication
thermal replica. The thermal replica will then have a value of 0. A reparameterization will also lead to resetting
the thermal replica.
Blocking the Stage
The function can be blocked externally or internally by the binary input signal
stage . Blocking will cause a picked up function to be reset.
6.39.3.2

Application and Setting Notes

Thermal overloads extended over a longer period will jeopardize electric equipment, for example, synchro-
nous motors, generators, or transformers and may cause damage. When using the thermal, user-defined char-
acteristic curve, the overexcitation protection lends itself perfectly for adjustment to the specified limits of the
protection equipment.
The following provides the recommended settings:
NOTE
i
i
It must be noted that one requirement for the correct mode of operation of the function is based on the
proper setting of the power-system data.
You can find more detailed information on this in chapter
For additional setting recommendations, verity the following parameter in the power-system data:
•
Adjusted rated frequency
•
Adjusted rated voltage of the protected object
•
Adjusted rated voltage of the voltage transformer of the applicable measuring point
Parameter: Threshold Value
•
Default setting (_:13591:3) Threshold = 1.10
The Threshold parameter is used to describe the value for the permissible continuous overexcitation.
The default value is a practical value used for transformers. The value may be less for generator applica-
tions. These values can be found in the manufacturer's information.
Parameter: Time Delayed Warning
•
Default setting (_:13591:101) Warning delay = 10.00 s
When using the Warning delay parameter, the time can be determined by which the warning indica-
tion of the stage should be delayed after the pickup. This time delay depends on the specific application.
This time must clearly exceed the reaction time of the regulators. 10 seconds is a feasible value.
Parameter: Cooling Time Therm. Replica
•
Default setting (_:13591:102) Cooling time therm.replica = 3600 s
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
(_:13591:501) >Reset thermal replica can be applied to reset the
Protection and Automation Functions
Description
Thermal tripping of the overexcitation protection. If
the value reaches 100 %, the tripping occurs.
(_:13591:81) >Block
6.1 Power-System Data.
6.39 Overexcitation Protection
821