Transformer Differential Protection T2Wpdif And T3Wpdif; Verifying The Settings - ABB Relion 670 Series Installation And Commissioning Manual

1MRK 502 029-UEN A
15.4.2
15.4.2.1
Installation and commissioning manual

Transformer differential protection T2WPDIF and T3WPDIF

Prepare the IED for verification of settings outlined in section
section "Preparing for test"

Verifying the settings

1. Go to Main menu/Test/Function test modes/Differential protection and
make sure that the restricted earth fault protection, low impedance function
REFPDIF is set to Off and that the four step residual overcurrent function
EF4PTOC under Main menu/Test/Function test modes/Current protection
is set to Off, since they are configured to the same current transformer inputs
as the transformer differential protection. Make sure that the transformer
differential functions T2WPDIF or T3WPDIF are unblocked.
2. Connect the test set for injection of three-phase currents to the current
terminals of the IED, which are connected to the CTs on the HV side of the
power transformer.
3. Increase the current in phase L1 until the protection function operates and
note the operating current.
4. Check that trip and alarm contacts operate according to the configuration logic.
5. Decrease the current slowly from operate value and note the reset value.
Depending of the power transformer vector group (Yd and so on), the single-
phase injection current may appear as differential current in one or two
phases and the operating value of the injected single-phase current will be
different.
6. Check in the same way the function by injecting current in phases L2 and L3
respectively.
7. Inject a symmetrical three-phase current and note the operate value.
8. Connect the timer and set the current to twice the operate value.
9. Switch on the current and note the operate time.
10. Check in the same way the functioning of the measuring circuits connected to
the CTs on the LV side and other current inputs to the transformer differential
protection.
11. Finally check that trip information is stored in the event menu.
Information on how to use the event menu is found in the
operator's manual.
12. If available on the test set a second harmonic current of about 20% (assumes
15% setting on I1/I2ratio parameter) can be added to the fundamental tone in
phase L1. Increase the current in phase L1 above the start value measured in
step 6. Repeat test with current injection in phases L2 and L3 respectively.
The balancing of currents flowing into and out of the differential zone is
checked by primary injection testing, see section "".
Fifth harmonic blocking can be tested in a similar way.
Verifying settings by secondary injection
in this chapter.
Section 15
"Overview" and
157