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3.9
General Notes for Setting the Threshold Value of Protection
Functions
Overview
3.9.1
You can set the threshold values of protection functions directly on the device or by using DIGSI 5.
An innovative design was implemented for the protection settings.
You can switchover the edit mode between the following setting views:
•
Primary
•
Secondary
•
Percent
If you change settings in a setting view, DIGSI 5 calculates the settings of the 2 inactive views in the back-
ground. If you wish to save, for example, conversion to secondary values, then select the primary view.
Configure all the settings and switchover to the secondary view.
Edit Mode: Primary
The parameters are set as primary values and thus refer directly to the primary system. The manual conversion
on the secondary circuit omitted.
Edit Mode: Secondary
The settings refer to the secondary circuit of the transformer. This means that the settings must be converted.
The secondary setting is the customary setting view. For secondary tests, the pickup values can be read
directly.
Edit Mode: Percent
This setting type is beneficial for electric machines (generators, transformers, motors, and busbars). The
setting values can be standardized regardless of the machine size. The reference values for the percentage
settings are the rated values of the function groups, for example, rated voltage and rated current or rated
apparent power . The setting values are, thus, related exclusively to the primary settings. If other reference
values are used, then this is documented for the respective protection function in the application and setting
notes.
If parameters are selected it may happen that they are set only in percent in all 3 setting views.
Recommendation for Setting Sequence
When setting the protection function, Siemens recommends the following procedure:
•
First set the transformation ratios of the transformers. You can find these under Power-system data.
•
In addition, set the reference parameters for the percent setting. You will find these parameters in func-
tion group .
•
Next, set the parameter of the protection functions.
If the transformer data have changed after completing the protection setting, remain in the setting sheet
(for example, primary setting) and change the transformer data. In the background, DIGSI 5 obtains the
new settings in the inactive setting views (for example, new secondary values).
The following section explains, by way of an example, how to modify the transformer ratios in DIGSI 5 using
the corresponding alternatives.
Modifying the Transformer Ratios in DIGSI 5
3.9.2
In the delivery setting, DIGSI 5 is set to the Secondary edit mode.
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
3.9 General Notes for Setting the Threshold Value of Protection Functions
System Functions
171
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