TAVRIDA ELECTRIC ISM_LD Series, Application Manual

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Regulations
The ISM fulfils the requirements of the following standards:
· DIN VDE 0670, Teil 1000 Germany
· IEC 60056 International standard
· IEC 62 271-100 International standard
· IEC 60 694 International standard
· GB 1984-2003 China
· GOST 687-78 Russian Federation
· ANSI C37.09 North American Standards
· ANSI C37.09a North American Standards
Ambient Conditions
Highest value ambient temperature + 55 °C
Average temperature over 24 hours + 35 °C
Lowest ambient temperature - 40 °C
Relative humidity in 24 hours max 98%
Relative humidity over 1 month max 90%
Average water vapour pressure over 24 hours max 2,2 kPa
Average water vapour pressure over 1 month max 1,8 kPa
Installation altitude
Up to an installation altitude of 1000 m above sea level, the acceptance need not take the dielectric strength of the
air into account. Above 1000 m, the external insulation measurement of the ISM must be increased by the atmospheric
correction factor Ka according to IEC 60 684 compared to the insulation measurement at sea level (Figure 69).
Example:
Installation altitude: 2500 m
Operating voltage: 12 kV
Rated power frequency
withstand voltage:
28 kV
Rated impulse withstand voltage 75 kV
Ka factor from diagram
1.2
At sea level the installation must resist the
following test voltage values:
Corrected rated power frequency
withstand voltage: 28 kV x 1.2 = 33.6 kV
Corrected rated impulse
withstand voltage: 75 kV x 1.2 = 90 kV
Because of the corrected voltage values, it
is necessary to select a 24 kV ISM.
Figure 60
Correction factor (Ka) for installation altitude (H) m = 1 correction curve
for the rated power frequency withstand voltage and rated lightning
impulse voltage.
m=1
1,00
1,10
1,20
1,20
1,10
1,00
1500
2000 2500 3000
3500
4000
Atmospheric corr
ection factor Ka
Installation altitude H(m)
1,50
1,40
1,30
1000
The EMC Directive 89/336/EEC
The Low Voltage Directive 73/23/EEC.
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