Alstom SHPM 101, Service Manual

Page: 295 / 336

SERVICE MANUAL R5888C
QUADRAMHO Chapter 6
Page 7 of 12
4.8 Zone 1 operation times
Zone 1 operation times should be checked by applying a fault at 50%
(approximately) of the Zone 1 reach.
An interval timer should be started when the fault is applied and stopped from the
any trip output SK2-11 of the 25 way monitor point box. A timer treats a
connection across SK2-2 and SK2-11 as a normally open contact.
The following points should be noted:
i) To obtain “fast” operating times is is essential to use dynamic tests starting with
all phase-neutral voltages above the level detector setting.
If this is not done filters in the voltage circuits will already be switched in and
the operation times will be slower.
ii) If the polarising quantities are not correctly provided by the test set some slower
times may be measured.
iii) The times vary with the point-on-wave of fault application it is thus suggested
that 10 operations be done for each type of fault.
iv) Times vary with the type of characteristic being used and the SIR.
v) Typical times expected are:
a) Shaped mho characteristic 12 – 27ms
b) Quadrilateral characteristic 17 – 32ms
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.
4.9 Memory feature check (synchronous polarising)
The memory is mainly to deal with 3 phase close up faults, but is made to run out
when any voltage level detector resets or when any comparator operates. There is
nominally 8 cycles of memory polarising which is derived from C phase volts.
The memory is re-connected 140ms after all voltage level detectors pick up and all
comparators have reset.
To satisfy the above conditions and make the relay behave as though it is seeing a
3 phase close-up fault.
This is achieved by applying a close-up C-N fault after removing the A and B
voltage inputs and connecting test plug 1Z terminals 1, 2 and 3 together (see
Figure 4).
If the dwell time of the trip contacts is now measured, this will give a measure of
the memory time.
On 50Hz the time measured should be 180 – 220ms.
On 60Hz the time measured should be 150 – 200ms.
4.10.1 Voltage level detectors
Select test option 43 (X = 4, Y = 3) all the LED now have a different function from
that on the nameplate. Apply volts in turn to each voltage input and check that the
LED indicated lights when 49 volts is applied and does not when 40 volts is