Schweitzer Engineering Laboratories SEL-387E - Page 118

3-70 Protection Functions Date Code 20080110
SEL-387E Instruction Manual
0.01
0.1
1
10
100
1000
10000
100 120 140 160 180 200
24C2T Operating Time
(seconds)
Volts/Hertz (%)
(24IP = 100%)
24ITD = 5.0
24ITD = 7.5
24ITD = 10.0
24ITD = 0.5
24ITD = 1.0
24ITD = 0.1
DWG: M300G149
2
3
sec
p
1
%100
IP24
10VNOM
NFREQ
•
freq
PTR•V•3
ITD24
t
⎟
⎟
⎟
⎟
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎜
⎜
⎜
⎜
⎝
⎛
−
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅
= seconds
Figure 3.43: Volts/Hertz Inverse-Time Characteristics, 24IC = 2