M25 0

Odnośniki

Smutek to uczucie, jak gdyby się tonęło, jak gdyby grzebano cię w ziemi.

79
0.77
0.75
0.73
0.71
1b 80x5
M16
0.87
0.85
0.83
0.81
0.79
M 08 ▼
800 A 1b 63x5 M08
1
1
1
1
1
empty
fig. 20: derating of the above circuit-breakers according to ambient temperature.
Cahier Technique Schneider n° 145 / p.19
The derating coefficients are therefore drawn up, See the curves in figure 22 concerning a non-by excess, placing devices in turn on the top of partitioned distribution cubicle type.
the cubicle or compartment. See for example c curves used to determine the watts that these figure 21.
envelopes can dissipate for a specific
temperature rise, as a function of their Curves characterising the thermal behaviour dimensional characteristics.
of a type of envelope For example: ext. ambient T° 35 °C, required Two types of graphs have been drawn up: max. temperature rise
c A set of curves used to determine the mean v cubicle: height 2 m, width 0.9 m, depth 0.4 m temperature within a specific envelope as a dissipable power: 850 W
function of the dissipated power and of the v cubicle: height 2 m, width 0.9 m, depth 0.6 m external ambient temperature.
dissipable power: 1000 W (see fig. 23.) IP31
IP 42/54
T°amb
35
40
45
50
55
35
40
45
50
55
C125N/H
0.95
0.91
0.88
0.84
0.80
0.82
0.79
0.76
0.72
0.69
C125L
0.94
0.90
0.86
0.83
0.79
0.80
0.77
0.74
0.71
0.68
C161N/H
0.95
0.92
0.88
0.85
0.82
0.81
0.78
0.76
0.73
0.69
C161L
0.94
0.91
0.87
0.84
0.82
0.79
0.76
0.73
0.70
0.67
Masterpact
C250N/H
0.94
0.90
0.87
0.83
0.80
0.82
0.79
0.76
0.72
0.69
Compact
C250L
0.93
0.89
0.86
0.82
0.78
0.79
0.76
0.73
0.70
0.67
C401N/H
0.94
0.91
0.87
0.84
0.81
0.79
0.76
0.74
0.72
0.69
fig. 21: derating of Compact circuit-breakers placed under the incoming circuit-breaker.
Mean temperature in °C
100
Tamb: 60 °C
90
Tamb: 55 °C
Tamb: 50 °C
80
Tamb: 45 °C
Tamb: 40 °C
70
Tamb: 35 °C
60
Tamb: 25 °C
50
40
Enclosure dimensions:
30
height: 2 m
width: 0.9 m
20
depth: 0.4 m
10
100 200 300 400 500 600 700 800 900 10001100 Power loss Watts fig. 22: mean temperature of air inside an IP2 form 1 metal distribution cubicle.
Cahier Technique Schneider n° 145 / p.20
400 mm deep enclosure
600 mm deep enclosure
Power dissipated
Power dissipated
in Watts
in Watts
1600
1600
∆T = 40 °C
1400
∆T = 40 °C
1400
∆T = 30 °C
1200
1200
1000
∆T = 30 °C
1000
800
1000
∆T = 20 °C
∆T = 20 °C
600
600
400
400
∆T = 10 °C
∆T = 10 °C
200
200
800
900
1000 1100
800
900
1000 1100
Width in mm
Width in mm
fig. 23: power that can be dissipated by an enclosure for a specific temperature rise according to its width.
Curves refer to a metal cubicle, form 1, 2 m high.
6.5 Experimental results Temperature rise tests have been conducted in the With respect to air temperatures, the difference ASEFA Ampère laboratory on various envelope between the values measured and the values types: metal and plastic enclosures, Prisma calculated depends on the type of envelope cubicle, Masterbloc distribution switchboards.
modelled, since modelling approaches differ During these tests the following measurements according to whether or not the envelopes are were taken:
partitioned.
c Temperatures:
Out of all the tests carried out on switchboards of v of air in the various envelope areas, various forms (partitioned or not), the maximum v of conductors: busbars and branch-offs, differences observed were always less than 6 °C.
v hot points in devices (bimetal strip, electronic The temperatures calculated for the busbars also ambient).
show satisfactory agreement with the
c Current strength.
measurements and enabled us to validate the c Parameters used for modelling, particularly air/
software.
wall heat exchange coefficients.
As regards current strengths, differences are on These measurements have enabled both
average less than 5%. Consequently, for a verification of conformity with IEC 439.1 standard recent official approval of a Masterbloc of certain values (see temperature rise limits switchboard configuration in temperature rise, mentioned in paragraph 1.2 on standards) and the software allowed us to determine the validation of this model.
operating level of the switchboard.
Cahier Technique Schneider n° 145 / p.21
8 Method proposed by the IEC 890 report Not so long ago a large number of electric cubicles were chosen and equipped/filled in the Effective cooling
Enclosure
light of experience. This concerns the filling ratio surface A
constant k
e in m2
and evaluation of temperature in the cubicle in operation. For example, the maximum external 0.38
temperature of 30 °C and maximum internal 1
0.36
temperature of 60 °C (switchgear manufacturers 0.34
give derating up to 60 °C).
1.5
0.32
This practice resulted in unoptimised use of the 2
0.30
equipment, untimely tripping of the protective 2.5
0.28
devices or the need for operators to operate with 3
0.26
open doors.
4
0.24
The method proposed by the IEC report, even if 5
0.22
6
this is rather a guide than a standard, thus merits 0.20
7
attention. It is described in detail in the report of 8
0.18
the IEC 890 or in the appendix of the
10
0.16
NF C 63-410.
12
0.14
14
We shall review the basic aspects, show its limits 0.12
and compare it with the method presented in the 0.10