SERVICE MANUAL R5888C
QUADRAMHO Chapter 5
Page 10 of 24
If the polarising quantities are not correct or if the voltage filters are in initially,
times may increase by 10 – 15ms. Times on 60HZ are approximately 10% faster.
The operation times should be checked for each phase-ground and each phase-
phase element.
4.10 Zone 2 operation times
Make sure the correct time is selected by the t
Z2
switches. (Also check t
Z3
is
greater). Apply a fault just outside Zone 1 and check the operation time as in
Section 4.9. This need only be done for one type of fault. The time measured will
be that of the software timer plus the comparator time plus the output contact
operation time.
The actual measured time should be within 40ms of the set time. Check for correct
indications and contact operation.
Note: The set time is the sum of the times of all the t
2
switches set to the right.
Check that 3 phase trips are given. Check that the block auto reclose
contact operates, if used (B25–B26).
4.11 Zone 3 operation times
If Zone 3 is not to be used for tripping then ∞ should be selected on the t
Z3
switches and no timing tests need be done.
If a time is set, check the setting as in Section 4.10 but applying a fault just outside
Zone 2.
The actual time should be within 40ms of the set time.
Check that correct indications are given and the appropriate contacts operate.
4.12 Power swing blocking checks
If this feature is to be used it can now be enabled by moving switch SW9 to the
right and the following checks carried out. The feature works from comparators on
A–B and utilises a Zone 6 in conjunction with Zone 3.
Zone 6 is automatically set with the Zone 3 switches to give:
Zone 6 forward (Z6) = Zone 3 forward + (0.3 x Zone 3 forward)
Zone 6 reverse (Z6') = Zone 3 reverse + (0.3 x Zone 3 forward)
A power swing is detected by an impedance being seen between Zone 3 and
Zone 6 for a time exceeding 50ms and then being seen inside Zone 3.
To check the Zone 6 boundary and the 50ms time it is necessary to utilise some of
the outputs that are made available by plugging the 25 way monitor point box into
socket 2 on Module 6. (Figure 6 gives all socket 2 outputs).
4.12.1 Zone 6 boundaries
A high impedance dc voltmeter should be connected from monitor point 2(–) to
7(+), when an impedance is seen inside Zone 6 the voltage will drop from about
24V to zero. For the forward boundary the required loop impedance is
2.6 x (K1 +K2) (K31 + K32) K33
ohms
I
n
and for the reverse boundary the required loop impedance is:
2 x (K1 +K2) K33 [(K35 + K36) K37 + 0.3 (K31 + K32)]
ohms
I
n
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