Schweitzer Engineering Laboratories SEL-321 - Distance Element Operating Time Curves at Nominal Frequency; Figure 2.48: Trip Unlatch Logic for Phase a

Date Code 20011026 Specifications 2-79
SEL-321/321-1 Instruction Manual
Figure 2.48: Trip Unlatch Logic for Phase A
DISTANCE ELEMENT OPERATING TIME CURVES AT NOMINAL FREQUENCY
Figure 2.49 shows operating times for the SEL-321 Relay distance elements. The diagrams show
operating times at each test point. Operating times include output contact closure time (for
standard and interrupting duty contact outputs).
For the distance element test, a fault was applied at a location representing a percentage of the
Zone 1 relay reach setting. Tests were performed for source impedance ratios (SIR) of 0.1, 1.0,
10.0, and 30.0. No pre-fault load current or fault resistance was included. Operating times are
the same for both 50 Hz and 60 Hz.