ABB Modures LZ92-1 - Page 24

Where the relays LZ92 or LZ92-l are being used with an off-set circular or
lenticular starting characteristic, the reach of the starters must be checked
and where necessary the c.t. connections reversed (see Section 5.3).
Depending on the main processing unit code (KI91, KZ91 or KZ91-1) in the
ordering code, one zone can be arranged to measure in the reverse direction.
This is done with switch respectively plug-in link Ba on PCB B (see Figures
9.30 and 9.31).
Code
RO.:
no provision made for zone reversal
(only main processing
units with
PCB 8 according to HESG 439
686)
Code Rl.: reversal
of
zone 1
selectable
Code R2.: reversal
of zone
2
selectable
Code R3.: reversal
of zone
3 selectable
Code
R4.: reversal of zone 4
selectable
Code RS.:
remote zone
reversal control
From the above it follows that it is necessary to state which zone is to be
reversed when ordering. However, should it be found during commissioning that a
different zone than the one ordered should be reversed, then the change can be
made with the soldered link LB9 on PCB 6 of the main processing unit KI91, KZ91
or KZ91-1 (see Fig. 9.2B).
'l'he PCB switch Ba (plug-in link Ba from order number HESG 440 71B) on PCB B
then determines whether all zones measure in the forwards direction (position
1), or whether the zone according to the ordering code (1, 2, 3 or 4) should
measure in the reverse direction (position 2) . This is not fitted in the case
of code RO. and order number HESG 439 6B6 (PCB B).
The directional sensitivity of the LZ91 and LZ92 is 100 mV (U = 100 to 130 V) .
The directional sensitivity of the cross-polarized LZ92-l isNunlimited for all
earth and phase-to-phase faults; a memory feature provides the polarizing
voltage to facilitate measurement of three-phase faults.
3.7 Zone 4
22
Normally the operating characteristic of zone 4 is that of the starting unit,
which is permitted to trip on its own after the time t (code for KI91 and KZ91:
EOO, links LBll and LB12 on PCB 7 soldered in).
Provision is made for using the X or R limits of zone 3 as blinders for zone 4
(code E :f 0) , which is achieved by removing the corresponding soldered link on
PCB 7 (X blinder with LBll removed and R blinder with LB12 removed) .
Switch 7 on PCB 7 (Fig. 9.29) enables zone 4 to operate either directionally
(position 1) or non-directionally (position 2). Non-directional operation means
that the whole of the starting characteristic is used for zone 4, compared with
directional operation with the starting characteristic cut off by the directio-
nal measurement so that tripping can only take place in the forwards direction.