Schweitzer Engineering Laboratories SEL-587Z - Equation 3.11

3.17
Date Code 20020903 SEL-587Z Instruction Manual
Relay Elements
Overcurrent Protection
Reset Time
Equation 3.11
U.S. Very Inverse Curve: U3
Operating Time
Equation 3.12
Reset Time
Equation 3.13
U.S. Extremely Inverse Curve: U4
Operating Time
Equation 3.14
Reset Time
Equation 3.15
U.S. Short-Time Inverse Curve: U5
Operating Time
Equation 3.16
Reset Time
Equation 3.17
I.E.C. Class A Curve (Standard Inverse): C1
Operating Time
Equation 3.18
Reset Time
Equation 3.19
tr TD
5.95
1M
2
–
----------------
• =
tp TD 0.0963
3.88
M
2
1–
----------------+• =
tr TD
3.88
1M
2
–
----------------
• =
tp TD 0.0352
5.67
M
2
1–
----------------+• =
tr TD
5.67
1M
2
–
----------------
• =
tp TD 0.00262
0.00342
M
0.02
1–
----------------------+• =
tr TD
0.323
1M
2
–
----------------
• =
tp TD
0.14
M
0.02
1–
----------------------
• =
tr TD
13.5
1M
2
–
----------------
• =