SERVICE MANUAL R5888C
QUADRAMHO Chapter 5
Page 19 of 24
Note: Timers will treat the voltage as a normally open contact provided terminal
2 goes to the common terminal on the timer.
5.4.4 Measurement of t
D
When the current reversal guard is picked up, transfer tripping is inhibited until the
permissive trip signal is removed or the Zone 2 comparator operates. A delay on
reset (t
D
) is required in case the Zone 2 comparator picks up while the permissive
trip signal is resetting which would otherwise cause a healthy circuit trip.
The recommended setting for t
D
is channel drop-off time plus 25ms or the nearest
available setting above.
The time is measured from the removal of the volts from the signal receive opto
isolator to the volts on monitor points 2(–) to 9(+) returning to about 24V.
The measured time should be within ±6ms of the set t
D
.
Note: Application Engineers should advise if the feature is not necessary in
which case t
D
tripping should be set to zero, which will give the smallest
possible delays to tripping.
Timers will treat the signal from the monitor point box as a normally closed
contact provided terminal 2 goes to the common terminal on the timer.
5.4.5 Signal receive check
Select test option 41 and check that the LED labelled SOTF is illuminated when the
double pole switch is closed.
This facility will be used in the signalling channel check later. Re-select the scheme
option.
5.4.6 Block auto reclose checks
Connect a single pole switch so that the channel in service opto isolator input
(A7(+) – A8) can be energised.
Switch SW6 controls whether or not auto reclose is blocked when the channel is
out of service. If SW6 is set to the right, check that the block auto reclose contact
(B25 to B26) is closed. Energise the channel in service input and check that the
block auto reclose contact opens.
If SW6 is set to the left, check that the block auto reclose contact does not close if
the channel in service signal is present or not.
5.4.7 Echo feature
To make this functional an opto isolator input has to be available to inform the
relay when the breaker is open. The feature causes signal send for 100ms on
receipt of carrier once the breaker has been open for 60ms.
If the feature is to be used check it as follows:
Connect a double pole switch so that one pole can be used to energise the
breaker open opto isolator input (A3(+) to A4) and the other pole to start a timer,
the switch should be open initially. A signal send contact (B1–B2 or B3–B4) should
initially be connected to stop the timer.
Energise the signal receive opto isolator (A9(+) to A10) then close the double pole
switch. A time of 65 to 75ms should be obtained.
Re-connect the timer to measure the dwell time of the signal send contact, open the
double pole switch, on reclosing the switch a time of 100 to 110ms should be
obtained.
To Next Page
Loading...