P54x/EN CM/La4 Commissioning
(CM) 10-38
MiCOM P543, P544, P545 & P546
CM
8.2 Demonstrate correct relay operation
Tests 5.2.10 and 5.2.11 have already demonstrated that the relay is within cal
ibration, thus
the purpose of these tests is as follows:
To determine that the primary protection function of the relay, current differential or
distance can trip according to the correct application settings
To verify correct setting of any aided scheme DEF (ground overcurrent) protection
To verify correct assignment of the trip contacts, by monitoring the response to a selection of
fault injections.
8.3 Demonstrate correct relay operation – current differential elements
8.3.1 Current differential bias characteristic
If the phase d
ifferential elements are enabled, they should be tested.
If the phase differential elements are not being used, proceed to section 8.4.
To avoid
spurious operation of any distance, overcurrent, earth fault or breaker fail elements,
these should be disabled for the duration of the differential element tests. This is done in the
relay’s CONFIGURATION column. Ensure that cells [090B: Distance], [090C: Directional
E/F], [0910: Overcurrent], [0913: Earth Fault] and [0920: CB Fail] are all set to “Disabled”.
Make a note of which elements need to be re-enabled after testing. The relay should also be
set to loopback mode isolating it from the remote end. Refer to Section 6.1.1.
8.3.1.1 Connect the test circuit
The follo
wing tests require a variable transformer and two resistors connected as shown in
Figure 5. Alternatively an injection test set ca
n be used to supply a and b.
A
A
Ra
Rb
Ph a
Ph b
L
N
Ia
Ib
P540
relay
Figure 5 Connection for bias characteristic testing
A current is injected into the A phase which is used as the bias current and another current is
injected into the B phase which is used as differential current. a is always greater than b.
8.3.1.2 Lower slope
If three
LEDs have been assigned to give phase segregated trip information, Trip A, Trip B
and Trip C, these may be used to indicate correct per-phase operation. If not, monitor
options will need to be used - see the next paragraph.
Go to the COMMISSION TESTS column in the menu, scroll down and change cells [0F05:
Monitor Bit 1] to 523, [0F06: Monitor Bit 2] to 524 and [0F07: Monitor Bit 3] to 525. Doing so,
cell [0F04: Test Port Status] will appropriately set or reset the bits that now represent Trip
Output A (DDB #523), Trip Output B (DDB #524) and Trip Output C (DDB #525) with the
rightmost bit representing Phase A Trip. From now on you should monitor the indication of
[0F03: Test Port Status]. Also make sure that the relay is in loopback mode by setting cell
[0F13 Test Loopback] to ‘External’ and applying either a loop-back fiber on the relay or
loopback is selected on the P590 as described in 6.1.1. Alternatively setting cell [0F13 Test
Loopback] to ‘Internal’.
Adjust the variac and the resistor to give a bias current of 1pu in the A-phase.
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