10
11
Table 2
Overcurrent tripping characteristics, type Release type
Test current
Non-tripping or tripping time
С; D
thermal release
1,13 I
n
t
≤
1 hour (at I
n
≤
63А) – without tripping
t
≤
2 hours (at I
n
> 63А) – without tripping
1,45 I
n
t < 1 hour (at I
n
≤
63А) – tripping
t < 2 hours (at I
n
> 63А) – tripping
2,55 I
n
1s < t < 60 s (at I
n
≤
32А) – tripping
1s < t < 120 s (at I
n
> 32А) – tripping
С
electromagnetic
release
5 I
n
t
≤
0,1 s – without tripping
10 I
n
t < 0,1 s – tripping
D
electromagnetic
release
10 I
n
t
≤
0,1 s – without tripping
15 I
n
t < 0,1 s – tripping
0.005
0.1
0.5
1
10
5
50
100
500
1000
10000
5000
1
10
20 30
0.01
2
3
8
40 60 80
1,13
1,45
120
60
30
10
5
2
1
I/In
2.55
5 60
40
Environment tempe30°С
Environment tempe30°С
Характеристика
C
Fig. 1 C characteristics
Environment tempe30°С
Environment tempe30°С
Характеристика
D
60
40
0.005
0.1
0.5
1
10
5
50
100
500
1000
10000
5000
1
10
20 30
0.01
2
3
8
40 60 80
1,13
1,45
120
60
30
10
5
2
1
I/In
2.55
5
14
Fig. 2 D characteristics
In Fig. 1, 2: dashed line – upper limit of time-current characteristic for
automated circuit breakers with rated current I
n
< 32 А
3.3 Changing tripping characteristics
3.3.1 К
t
rating reflecting the change in MCB load depending on the ambient
temperature is shown in Figure 3.
Ambient temperature °С
K
t
r
ating
1,4
1,6
1,2
1
0,8
-40-
30
-20-
10
10
20
30
40
0
°C
K
t
50
0,9
1,1
1,3
1,5
Fig. 3
NOTE: Non-tripping current of MCBs depending on the ambient temperature
(°С) is determined using the following formula: I = 1,13 I
n
K
t
,
where I
n
– rated current (indicated on the marking) at the temperature of
thermal release adjustment amounting to 30°С;
K
t
– load rating depending on the ambient temperature.
3.3.2 К
n
rating reflecting the change in MCB load depending on the number
of poles placed close to each other is shown in Figure 4.
12
3
4
5
67
8
0.70
0.80
0.90
1.00
1.10
K
N
N
Fig. 4
NOTE: Non-tripping current for MCBs placed close to each other depending
on their number (N) and ambient temperature (°С) is determined using the
following formula:
I = 1,13 I
n
K
N
K
t
,
where I
n
– rated current (indicated on the marking) at the temperature of
