SERVICE MANUAL R5888C
QUADRAMHO Chapter 5
Page 17 of 24
The recommended setting is:
t
D
= 0 if the channel reset time is 10ms or greater than 10ms.
t
D
= 12ms if the channel reset time is less than 10ms.
Note: If t
d
is set to 0 or 6ms, the time actually measured can be as high as 5 or
6ms. This is due to the effect of the microprocessor loop execution time
and the point where it is interrupted.
When t
d
is set to 12ms times of 10 to 15ms will be obtained.
5.3.1 Measurement of t
D
Connect a double pole switch so that one pole can energise the signal receive
opto isolator input (A9(+) to A10) and the other pole to start a timer set to start
from a normally closed contact.
A signal is available from the 25 way monitor point box (terminals 2 to 9) to stop
the timer. When the voltage is removed from A9 the voltage on the monitor points
2(–) and 9(+) will go from zero to 24V, (timers will treat this as a normally closed
contact if 2 is connected to the common connection of the timer).
The rising voltage is used to stop the timer. When the double pole switch is opened
the appropriate time for t
D
will be obtained in the range previously described.
5.3.2 Aided trip and t
p
check
Connect a single pole switch to energise the channel in service opto isolator input
terminals A7(+) to A8. Check that the double pole switch used for test 5.3.1. is
closed.
Apply a Zone 2 fault and check that a trip is obtained in Zone 2 time. Open the
double pole switch and check that an instantaneous aided trip is obtained. Set t
p
to
zero (ie. all t
p
switches to the left) apply a Zone 2 fault and measure the aided trip
operating time. This should be repeated 5 to 10 times and the average operation
time calculated.
Put the required setting on the t
p
switches and find the new average aided trip
operation time. The difference between the two average times will give 6ms less
than the set t
p
time (6ms is the average processing and loop time when t
p
= 0) with
a tolerance of ±5ms.
5.3.3 Signal send check
Apply a reverse Zone 3 fault and check that the signal send contacts (B1–B2 and
B3–B4) close. There is also a test option which can be used to cause the signal
send contact to close which is useful for checking the signalling channel on the
system. Select test option 62 with SW8 to the right and check for signal send.
Note: that other contacts may operate depending on the position of the other
SW switches.
5.3.4 Signal receive check
There is another test option 41 which enables the checking of the signal receive.
With the test option selected the LED labelled SOTF will illuminate when the opto
isolator input (A9(+) to A10) is energised. This is also used later for checking the
system signalling channel.
5.3.5 Block auto reclose checks
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