Differential Protection Test Mode - Siemens SIPROTEC 7SD610 Manual

2.2.2.2 Differential Protection Test Mode

General
If differential protection test mode (test mode in the following) is activated, the differential protection is blocked
in the entire system. Depending on the configuration, the overcurrent protection becomes effective as an emer-
gency function.
In the local device, all currents from the other devices are set to zero. The local device only evaluates the locally
measured currents, interprets them as differential current but does not send them to the other devices. This
enables to measure the thresholds of the differential protection. Moreover, the test mode prevents the genera-
tion of an intertrip signal in the local device by tripping of the differential protection.
If the device is still connected to the local CT the measured current can lead to a trip of the device.
If the device was logged out of the line protection system before activating the test mode (see "Log out device"
mode), the differential protection remains effective in the other device. The local device can now also be tested.
The test mode can be activated/deactivated as follows:
• Using the integrated keypad: Menu Control/Taggings/Set: „Test mode"
• Via binary inputs (No. 3197 „>Test Diff. ON", No. 3198 „>Test Diff. OFF") if this was allocated
• In DIGSI with Control/Taggings: „Diff: Test mode"
The test mode status of the other device of the line protection system is indicated on the local device by the
indication „TestDiff.remote" (No. 3192).
Principle of function
In the following, the logic is shown in a simplified way:
Figure 2-8
Depending on the way used for controlling the test mode, either the indication Depending on the way used for
controlling the test mode, either the indication „Test Diff.ONoff" (No. 3199) or „TestDiffONoffBI"
(No. 3200) is generated. The way used for deactivating the test mode always has to be identical to the way
used for activating it. The indication „Test Diff." (No. 3190) is generated independently of the selected
way. When deactivating the test mode via the binary inputs, a delay time of 500 ms becomes effective.
The following figures show possible variants for controlling the binary inputs. If a switch is used for the control
(Figure 2-10), it has to be observed that binary input „>Test Diff. ON" (No. 3197) is parameterised as NO
contact and that binary input „>Test Diff. OFF" (No. 3198) is parameterised as NC contact.
SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011
Logic diagram of the test mode
2.2 Protection Data Interfaces and Protection Data Topology
Functions
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