SERVICE MANUAL R5888C
QUADRAMHO Chapter 6
Page 8 of 12
applied. If preferred the precise pick-up can be determined and the drop-off should
be within 10% of that value.
Level detector Terminals injected LED marking
A phase 1Z 1-4 A
B phase 1Z 2-4 B
C phase 1Z 3-4 C
Note: During test option checks only the LEDs mentions are of concern in a
particular test; others may be on and can be ignored. However, a full
table is given in Figure 1.
4.10.2 Fixed current level detector checks
i) Low set current level detectors
Each phase current is monitored and the setting is changed by the value of K1
and K2 selected on module1, the most sensitive setting is 5% I
n
.
Current setting =
5
x
4.8
100 K1 + K2
x I
n
A (±10%)
I
n
= relay rated current
Keep test option 43 selected and inject current into each pair of phase
terminals, on the left hand side of the 1Y test block, in turn. Determine the pick-
up as indicated below; the drop-off should be within 10% of actual pick-up.
Level detector Terminals injected LED marking
A phase 1Y 1-2 Z3
B phase 1Y 3-4 Aided trip
C phase 1Y 5-6 SOTF
ii) High set current level detectors
Current setting =
12.1
x
4.8
100 K1 + K2
x I
n
amps (±10%)
Select test option 53 and inject current as in the previous test. Determine the
pick-up, drop-off should be within 10% of the actual pick-up.
Level detector Terminals injected LED marking
A phase 1Y 1-2 Z3
B phase 1Y 3-4 Aided trip
C phase 1Y 5-6 SOTF
4.10.3 Auto ranging low set and high set residual current level detectors
The auto-ranging only comes into action when a minimum setting is exceeded.
The residual signal is derived by summing the vectors of the voltages in the relay
which are proportional to the phase currents.
The operational level when auto ranging, varies directly with the highest phase
difference current until a limit is reached. The minimum operate level varies
inversely with K1 + K2.
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