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Date Code 20011026
Specifications
2-81
SEL-321/321-1 Instruction Manual
Equations for US Curves
t
M
= curve operating time in seconds
t
r
= reset time in seconds (for time delay reset)
TD = time dial setting
M = multiples of pickup. For curve operating time (t
M
), M>1.
For reset time (t
r
), M
≤
1.
Curve U1: Moderately Inverse - See Figure 2.50
úû
ù
êë
é
−
+
=
1
M
0104
.
0
0226
.
0
TD
t
02
.
0
m
2
r
M
1
08
.
1
TD
t
−
⋅
=
Curve U2: Inverse - See Figure 2.51
úû
ù
êë
é
−
+
=
1
M
95
.
5
180
.
0
TD
t
2
m
2
r
M
1
95
.
5
TD
t
−
⋅
=
Curve U3: Very Inverse - See Figure 2.52
úû
ù
êë
é
−
+
=
1
M
88
.
3
0963
.
0
TD
t
2
m
2
r
M
1
88
.
3
TD
t
−
⋅
=
Curve U4: Extremely Inverse - See Figure 2.53
úû
ù
êë
é
−
+
=
1
M
67
.
5
0352
.
0
TD
t
2
m
2
r
M
1
67
.
5
TD
t
−
⋅
=
Summary of Contents for SEL-321
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Page 171: ...Date Code 20011026 Event Reporting 4 9 SEL 321 321 1 Instruction Manual ...
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