Loss Of Current Monitoring (Loi); Overcurrent Supervision; Trip/Highset Trip Logic; Close-Into-Fault Trip (Cift) And Stub-Bus Protection (Sbp) Logic - ABB REL300 Instruction Manual

I.L. 40-385.7
a) NO – No trip block on LOP condition.
b) DIST – Block the distance units. Convert the high set (ITP & ITG) and ground backup (GB)
to non-directional automatically. (Also see 3.4.6)
c) ALL – Block all types of trip and turn off the "IN SERVICE" LED.
3.4.4

Loss of Current Monitoring (LOI)

The ac current monitoring circuit uses I
(page 3-35). Under ct short circuit or open circuit condition, I
the output signal of AND-23 starts the 10/0.5 sec. timer. The timer output turns "ON" the non-
memory LOI indicator, which is shown in the Metering mode, and picks up the GS (AL-3) relay.
If the LOI condition exists and LOIB is set at YES, the trip will be blocked after the 10 sec. timer
times out.
3.4.5

Overcurrent Supervision

For REL300, as shown in Figure 3-13 (page 3-36), the distance units do not require overcurrent
supervision; because the relay normally operates in a background mode, they will not start the
Zone 1 and pilot impedance computation until a phase current or a phase voltage disturbance
is detected. This approach can minimize the load problem when setting the phase overcurrent
units. However, in order to meet the traditional practice, a medium set phase overcurrent unit
IM (IAM or IBM or ICM) has been added to REL300 version 2.20 to supervise Z1P/Z2P/Z3P/
PLTP trip functions, as shown in Figure 3-13. (Note, older versions do not have this unit). This
unit should not be set to limit the Zone 3 reach, and traditionally should be set above the load
current.
For coordination purposes the ground trip units (Z1G, Z2G, Z3G, PLTG, and FDOG) are super-
vised by the medium set ground overcurrent unit (I
for carrier send in a Pilot Blocking system.
3.4.6 Instantaneous Forward Directional Overcurrent Trip/Highset Trip Logic
The instantaneous overcurrent units (I
and high to detect those faults which occur in the Zone 1 area, therefore, their tripping will occur
via OR-2 for HST, as shown in Figure 3-14 (page 3-36). These high set trip functions can be
disabled by setting the ITP (phase) and/or ITG (ground) to the OUT position. The directional
unit (ITP and ITG) will be automatically converted to non-directional protection if the LOP con-
dition occurs and the setting of LOPB = DIST.
3.4.7

Close-Into-Fault Trip (CIFT) and Stub-Bus Protection (SBP) Logic

Close-Into-Fault and Stub-Bus- protection functions supplement the distance unit operation for
installations where line-side potential sources are used for the distance relaying. The logic for
both functions is combined as shown in Figure 3-15a (page 3-37), and is under the control of
a single setting, CIF. In a change from earlier firmware versions, a modified CIFT logic employ-
ing a 200/0 msec delay timer on the low voltage sensing, can be selected instead of the stan-
dard CIFT logic. This application is special in nature, and will be discussed later.
The CIF setting has six values, as follows:
3-8
(and not Vo) as criterion, as shown in Figure 3-12
0M
0M
). The IOS setting and RDOG are used
OM
, I , I and I ) are normally set forward directional
AH BH CH OH
(and not Vo) satisfies AND-23;