Table of Contents
Advertisement
b.
The "TEST" display mode also provides access for testing for REL 301/302 output relay
contacts. All output relays will be tested using the procedure described in Step 12. In asso-
ciation with the contact test, receiver 1 and/or 2 units can be simulated for verification of
REL 302 pilot logic. These input simulations will be used later in Section 5.2 Pilot Accep-
tance Tests for REL 302.
As previously stated, when REL 301 or REL 302 are energized the system performs a complete
self-test/startup/initialization routine. Upon successful completion of the startup routine the sys-
tem firmware enters what is referred to as the background mode. In the background mode all
"non-fault analysis" functions are performed. In the background mode, current and voltage sam-
pling is done continuously (2 millisecond resolution) as well as the calculation of current and
voltage phasors. Also, when the system is in background mode MMI functions and (continuous)
self-checking are performed. See Figure 1-6 for software flowchart reference.
Tripping decisions are made in the fault mode. Both the REL 301 and REL 302 utilize a unique
disturbance detector that is used to switch from background mode to fault mode processing. In
fault mode only processing related to fault calculation trip logic analysis are done. All back-
ground mode functions not related to tripping are stopped.
The operate criteria for the disturbance detector (Fault Detector) are:
Phase current (∆IA, ∆IB, or ∆IC) > 1.0A peak and 12.5% change
Ground current (∆I0)>0.5 A peak
Phase voltage (∆VA, ∆VB, or ∆VC) >7V and 12.5% change with a current change of ∆I>0.5 A
When one of the above is met, REL 301 or REL 302 will switch to fault mode processing.
In order to perform all tests, voltages will be applied first then the designated value of current
has to be suddenly applied. If REL 301 or REL 302 does not trip, adjust the current to a higher
value, and then suddenly reapply current. Unlike conventional electromechanical relays, slowly
ramping up the current will not cause Zone 1tripping. The current required to trip is shown for
each test.
5.1.4
Zone 1 Impedance Accuracy Check
STEP 6
The following impedance accuracy tests use a predetermined fault voltage and current for the
test impedance applied to the system under test. If it is desired by the user to test impedance
accuracy at another impedance setting, the following formula can be used to calculate test cur-
rent for any phase-to-ground fault, impedance setting:
From Table 5-4 (for example):
• "Zone1 G" = "4.5 Ohms"
• "Ang Pos." = "75°"
• "ZOL/Z1L" = "3.0"
V
LN
I
=
-------------------------------------------------------------------------------------------- -
(
) 1
Z
COS PANG X
–
1G
(
)
Z
–
1
R
+
-------------------- -
3
I.L. 40-386.1
5-7
Hide quick links:
Advertisement
Table of Contents
