Schweitzer Engineering Laboratories SEL-351 - SSI Triggering and Recording

12-36 Standard Event Reports, Sag/Swell/Interruption Report, and SER Date Code 20001006
SEL-351 Instruction Manual
SAG/SWELL/INTERRUPTION (SSI) REPORT (AVAILABLE IN FIRMWARE VERSIONS
3 AND 4)
See Figure 12.6 for an example SSI report.
SSI Triggering and Recording
The relay triggers (generates) entries in the SSI report on a rising edge of any sag, swell, or
interruption relay element. The report entries contain the following information:
• Phase current magnitudes as a percentage of nominal current: I
A,B,C
• Calculated residual current magnitude as a percentage of nominal current: I
G
• Neutral current magnitude as a percentage of nominal current: I
N
• Phase voltage magnitude as a percentage of the base voltage: V
A,B,C
• Synchronizing voltage magnitude as a percentage of the base voltage: V
S
• Base voltage magnitude - memorized positive-sequence voltage: V
BASE
• SSI element type asserted: PRE, SAG, SWELL, INT, or POST
♦ PRE - Recorded for all pre-disturbance entries (no SSI elements asserted).
♦ SAG - One or more sag elements asserted.
♦ SWELL - One or more swell elements asserted.
♦ INT - One or more interruption elements asserted.
♦ POST - Recorded when all SSI elements dropout
The relay archives SSI data in the following manner:
1. Archive eight pre-disturbance records. These records correspond to ¼, ½, ¾, 1, 1¼, 1½, 1¾
and 2-cycles before the SSI trigger.
2. Archive one record every ¼-cycle for the next five cycles regardless of SSI element state.
3. If any SSI element remains asserted following the pre-disturbance and initial five cycles,
archive one record once per cycle for up to 55-cycles.
4. If any SSI element remains asserted beyond 60-cycles, archive one record if a phase voltage,
phase current, or residual current RMS magnitude changes by either 10%, or 6 volts or 3 amps
(0.6 amps; 1 A nom.) secondary from the previous cycle.
5. If any SSI element remains asserted for 24 hours, archive one record.
6. If all SSI elements drop out, archive one record and reset recorder.
Courtesy of NationalSwitchgear.com