Alstom SHPM 101, Service Manual

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SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 20 of 74
4.9.29 LLAD subroutine
The LOAD routine now runs another routine called LLAD. This reads all the input
ports of the microcontroller and peripherals and stores all these inputs in internal
memory for use later on in the program. The inputs loaded consist of the following:
a) t
p
and t
d
switch bank settings.
Zone 2 switch bank settings.
Zone 3 switch bank settings.
OPTION switch bank settings.
b) All level detector outputs.
c) Push button state.
This routine also clears all the registers that are designated output registers
(described earlier).
4.9. 30 PDTIM subroutine
The PDTIM subroutine runs the pole dead pick up timers and sets the pole dead
outputs and internal flags. These flags are used by several subroutines within the
main loop. The pole dead logic is explained in Section 5.9.
4.9.31 VTS subroutine
The voltage transformer supervision (VTS) is described in Section 6.
4.9.32 LOAD 1 subroutine
The LOAD 1 subroutine reads the Zone 1, 2 and 3 comparators and performs level
detector checks on them (See Section 5.8). The comparator 6 bit format (A, B, C,
A–B, B–C & C–A) is converted to 4 bit format (A, B, C & N). It also sets internal
flags to indicate that a fault has occurred in a particular zone. If the VTS has issued
a “block comparator“ signal then the comparators will be software inhibited within
this routine.
4.9.33 FLOC subroutine
The FLOC subroutine generates the fault locator outputs (see Figure 74 for the logic
equivalent). For all schemes the fault locators normally operate based on the
Zone 1 and Zone 2 comparators (Zone 3 is not used), but this can be overridden
by the SOTF (SWITCH ON TO FAULT) Feature
The FLOC subroutine also sets an internal flag which indicates that any comparator
has operated.
4.9.34 SOTF subroutine
The SOTF operation is described in Section 5.16.39 Sotf fault locators.
Under normal scheme operation the fault locators operate on the comparator
information as mentioned earlier
If the SOTF feature is selected to operate on current and no volts (CNV) during the
SOTF enable time the fault locators will operate on the CNV condition that has
caused the trip. The fault locators will follow the CNV condition for the SOTF
enable time (240ms after all poles established) or until the CNV condition has
been removed, whichever is the longest.
The SOTF feature disables the basic scheme and prevents the carrier schemes from
issuing a trip. It should be noted that if a SOTF trip is still present after the SOTF
enable timer has run out, the SOTF will remain enabled until the fault has been
cleared.