Date Code 20011009
SEL-701-1 Monitor
Settings Calculation
Basic Motor Protection
3.19
Phase current transformers having 500:5 ratios are selected for the
application. The SEL-701-1 Monitor settings for the application are
calculated as shown below.
Current Transformer Ratio (CTR) = 500/5 = 100
CT Secondary Rating (ITAP) = 5
Full Load Amps (FLA) = 366/100 = 3.66 A secondary
Service Factor (SF) = 1.25
Time to Trip at 1.30 x FLA (TTT130) = NP
Time to Trip at 1.40 x FLA (TTT140) = NP
Time to Trip at 1.50 x FLA (TTT150)
= NP
Time to Trip at 1.75 x FLA (TTT175) = 625.0 seconds
Time to Trip at 2.00 x FLA (TTT200) = 400.0 seconds
Time to Trip at 2.25 x FLA (TTT225) = NP
Time to Trip at 2.50 x FLA (TTT250) = 225.0 seconds
Time to Trip at 2.75 x FLA (TTT275) = NP
Time to Trip at 3.00 x FLA (TTT300) = NP
Time to Trip at 3.50 x FLA (TTT350) = NP
Time to Trip at 4.00 x FLA (TTT400) = 72.0 seconds
Time to Trip at 4.50 x FLA (TTT450) = 58.0 seconds
Time to Trip at 5.00 x FLA (TTT500) = 30.0 seconds
Time to Trip at 5.50 x FLA (TTT550) = 25.0 seconds
Time to Trip at 6.00 x FLA (TTT600) = 18.1 seconds
Time to Trip at 6.50 x FLA (TTT650) = 15.2 seconds
Time to Trip at 7.00 x FLA (TTT700) = 13.2 seconds
Time to Trip at 7.50 x FLA (TTT750) = NP
Time to Trip at 8.00 x FLA (TTT800) = NP
Time to Trip at 8.50 x FLA (TTT850) = NP
Time to Trip at 9.00 x FLA (TTT900) = NP
Time to Trip at 10.00 x FLA (TTT1000) = NP
The monitor neither requests settings for thermal limit times less
than the service factor nor does it require that all settings have a
time entered. You can enter NP for some points and the monitor
Table 3.10
3000 HP Motor Thermal Limit Times
Multiples of Full Load
Current
Thermal Limit Time (Sec)
1.75
625
2.00
400
2.50
225
4.00
72
4.50
58
5.00
30
5.50
25
6.00
18.1
6.50
15.2
7.00
13.2
Summary of Contents for SEL-701-1
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