Temperature Considerations
Correction Factor
The overload protection is calibrated at 40°C. This means that when the ambient temperature is less than or greater than 40°C, the In protection pick-up is slightly modified.
Derating Depending on the Temperature
Over the reference temperature of 40°C (104°F), the circuit breaker has to be derated following the table below:
Correction Factor Table for PowerPact B-frame Circuit Breakers
|
Rating (In) (A) |
Temperature (°C / °F ) |
||||||
|---|---|---|---|---|---|---|---|
|
40 / 104 |
45 / 113 |
50 / 122 |
55 / 131 |
60 / 140 |
65 / 149 |
70 / 158 |
|
|
15 |
15 |
14 |
14 |
13 |
12 |
12 |
11 |
|
20 |
20 |
19 |
19 |
18 |
18 |
17 |
16 |
|
25 |
25 |
24 |
24 |
23 |
22 |
21 |
20 |
|
30 |
30 |
29 |
28 |
27 |
26 |
25 |
24 |
|
35 |
35 |
34 |
33 |
32 |
31 |
31 |
30 |
|
40 |
40 |
39 |
38 |
37 |
36 |
35 |
33 |
|
45 |
45 |
44 |
42 |
41 |
39 |
37 |
36 |
|
50 |
50 |
49 |
47 |
45 |
44 |
42 |
40 |
|
60 |
60 |
58 |
56 |
55 |
53 |
51 |
48 |
|
70 |
70 |
67 |
64 |
61 |
59 |
55 |
53 |
|
80 |
80 |
77 |
73 |
70 |
67 |
63 |
59 |
|
90 |
90 |
87 |
83 |
80 |
76 |
72 |
68 |
|
100 |
100 |
99 |
96 |
92 |
85 |
80 |
69 |
|
110 |
110 |
107 |
103 |
99 |
94 |
89 |
76 |
|
125 |
125 |
121 |
117 |
112 |
109 |
104 |
100 |
Calculating Tripping Time
Calculating the Tripping Time for a Given Temperature:
After having determine the corrected ratio I/In, the tripping time at 40°C (104°F) is defined with the tripping curves (Trip Curves). Then to obtain the tripping time at a different temperature, the ratio I/In has to be corrected with the correction factor below:
Correction Factor Table for PowerPact B–Frame Circuit Breakers
|
Rating (In) (A) |
Temperature °C (°F ) |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
10 |
15 |
20 |
25 |
30 |
35 |
40 (104) |
45 (113) |
50 (122) |
55 (131) |
60 (140) |
65 (149) |
70 (158) |
|
|
15 |
1.21 |
1.18 |
1.15 |
1.11 |
1.05 |
1.04 |
1 |
0.96 |
0.92 |
0.87 |
0.83 |
0.78 |
0.72 |
|
20 |
1.16 |
1.13 |
1.11 |
1.08 |
1.06 |
1.03 |
1 |
0.97 |
0.94 |
0.91 |
0.88 |
0.85 |
0.81 |
|
25 |
1.15 |
1.13 |
1.11 |
1.08 |
1.05 |
1.03 |
1 |
0.97 |
0.94 |
0.91 |
0.88 |
0.85 |
0.82 |
|
30 |
1.16 |
1.14 |
1.11 |
1.08 |
1.06 |
1.03 |
1 |
0.97 |
0.94 |
0.91 |
0.87 |
0.84 |
0.80 |
|
35 |
1.13 |
1.11 |
1.09 |
1.07 |
1.05 |
1.02 |
1 |
0.98 |
0.95 |
0.93 |
0.90 |
0.87 |
0.85 |
|
40 |
1.14 |
1.12 |
1.10 |
1.07 |
1.05 |
1.03 |
1 |
0.97 |
0.95 |
0.92 |
0.89 |
0.86 |
0.83 |
|
45 |
1.17 |
1.15 |
1.12 |
1.09 |
1.06 |
1.03 |
1 |
0.97 |
0.94 |
0.90 |
0.87 |
0.83 |
0.79 |
|
50 |
1.16 |
1.14 |
1.11 |
1.08 |
1.06 |
1.03 |
1 |
0.97 |
0.94 |
0.91 |
0.87 |
0.84 |
0.80 |
|
60 |
1.16 |
1.14 |
1.11 |
1.08 |
1.06 |
1.03 |
1 |
0.97 |
0.94 |
0.91 |
0.88 |
0.84 |
0.81 |
|
70 |
1.18 |
1.15 |
1.13 |
1.10 |
1.06 |
1.03 |
1 |
0.96 |
0.91 |
0.88 |
0.84 |
0.79 |
0.75 |
|
80 |
1.19 |
1.15 |
1.12 |
1.09 |
1.06 |
1.03 |
1 |
0.96 |
0.92 |
0.88 |
0.83 |
0.79 |
0.74 |
|
90 |
1.19 |
1.15 |
1.12 |
1.10 |
1.06 |
1.04 |
1 |
0.96 |
0.92 |
0.89 |
0.84 |
0.80 |
0.75 |
|
100 |
1.21 |
1.18 |
1.15 |
1.12 |
1.09 |
1.05 |
1 |
0.99 |
0.96 |
0.92 |
0.85 |
0.80 |
0.69 |
|
110 |
1.19 |
1.16 |
1.13 |
1.10 |
1.07 |
1.04 |
1 |
0.98 |
0.94 |
0.90 |
0.85 |
0.80 |
0.70 |
|
125 |
1.17 |
1.14 |
1.12 |
1.09 |
1.06 |
1.03 |
1 |
0.96 |
0.94 |
0.90 |
0.87 |
0.83 |
0.80 |