Oscillography - GE ALPS Instruction Manual

2.2 GENERAL SETTINGS
301: NUMFAULTS - Number Of Faults To Be Captured
NUMFAULTS selects the maximum number of oscillography "storage events" (faults) that are stored in memory. When the
maximum number of events are reached, the oscillography data associated with a subsequent storage event will overwrite
the data from the oldest event.
This setting allows the user to apportion a fixed amount of memory into different sized blocks for oscillography storage.
2
Table 2–5: OSCILLOGRAPHY CYCLES PER STORAGE EVENT shows the total number of oscillography cycles allowed
per storage event as a function of the NUMFAULTS setting.
Table 2–5: OSCILLOGRAPHY CYCLES PER STORAGE EVENT
STANDARD MEMORY
NUMFAULTS
2
4
8
12
302: PREFAULT - Number Of Pre-Fault Cycles To Capture
PREFAULT selects the number of pre-fault or pre-trigger cycles to be stored in each oscillography record. It can be set over
the range from 1 to 8. NUMFAULTS, as explained above, determines the total number of cycles per oscillography record,
and PREFAULT determines how many of these will be pre-fault cycles.
303: SPLITREC - Split Oscillography Record For Long Duration Faults
The ALPS allows a pre-defined number of oscillography records to be captured per the NUMFAULTS setting described
above. Each record is a specific number of cycles long as determined by this setting. If a fault occurs that is greater in
length than the number of cycles set to be captured, the SPLITREC setting will allow the record to be split so that the begin-
ning and the end of the fault can be captured. Note that SPLITREC does not affect the number of pre-fault cycles that are
captured as determined by the PREFAULT setting. SPLITREC applies only the fault record exclusive of the pre-fault
cycles. SPLITREC is set as a percentage with a range of 0 to 100%, and splits the record so that the end of the record is
equal to the SPLITREC percentage and the beginning of the record is equal to (100 – SPLITREC). For example, assume
that NUMFAULTS is set to 4 and PREFAULT is set to 4. This means that the record will capture 4 cycles of pre-fault data
and 32 cycles of fault data. The ALPS samples at 64 times per cycle, therefore, 2048 samples (64 x 32) of fault data will be
captured. Further assume that SPLITREC is set to 30%. If the fault lasts longer than 32 cycles (2048 samples), then the
oscillography record will be split and the display will show 8.4 cycles (538 samples) at the end and 23.6 cycles (1510 sam-
ples) at the beginning. If the fault is less than the set number of cycles then SPLITREC has no effect and the total fault
record will be displayed.
Use a setting for SPLITREC that will display the information most desired in a long duration fault. (more at the beginning
and less at the end or vice versa).
The ALPS will count the total number of breaker operations as well as calculate and accumulate the total breaker duty on a
per phase basis according to the following equation:
∑
x
Total Duty = I t
where: I = RMS current
t = breaker operating time
x = user defined exponent
The number of operations and accumulated duty will be compared to set values (entered by user). When the respective
value is reached, an event will be recorded and the non-critical alarm will be initiated if programmed to do so. The number
of operations and the total duty can start from zero, or if the existing number of operations or total duty is known, those val-
ues can be entered into the ALPS to use as a starting point. The following settings need to be made.
2-6
STORAGE CYCLES NUMFAULTS
72
36
18
12
ALPS Advanced Line Protection System
EXPANDED MEMORY
STORAGE CYCLES
6 72
12 36
24 18
36 12
2 CALCULATION OF SETTINGS

2.2.3 OSCILLOGRAPHY

2.2.4 EQUIPMENT DUTY
GE Power Management