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The minimum air
clearance measurement defined IEC 60947-7-1 in
conjunction with the rated surge voltage. These rated currents cause
no impermissible heat transfer the terminal:
mm2
1.2 0.1 lEC 60947-1.0 –
16 120 150 240 300 mm2
. The conductors can solid, stranded or
flexible, possibly with conductor end pretreatment.
The verification the rated cross-section performed
with gauges according IEC 60947-1. Pollution
severity has been specified for terminal blocks for industrial
applications: conductive contamination occurs dry,
non-conductive contamination which becomes conductive
as moisture condensation may also occur.
Operating conditions
The terminal blocks can operated under
the following normal conditions:
• Ambient temperature +40 °C,
mean value +35 °C
• Altitude 2000 above sea level
• Relative humidity: +40 °C, +20 °C
C.75 1. This serves reference for certain thermal,
mechanical and electrical requirements.
Terminal blocks have rated connection capacity
that least two levels lower than the rated cross-
section. The rated cross-
section selected from the following standard cross-
sections: 0. determined analogously IEC 60664-1.2.5 4.5 41
mm2
10 35
A 101 125
mm2
50 120
A 150 192 232 269
mm2
150 185 240 300
A 309 353 415 520
Conventional free-air thermal current (Ith)
The conventional thermal current free air (Ith) the
highest test current for heating tests unenclosed devices
(see 4.
Rated impulse withstand voltage IEC 60947-7-1
Rated impulse withstand voltage the peak value surge
voltage with which the terminal blocks can subjected.0 1.Technical requirements from the standards
Rated cross-section
The rated cross-section terminal block the value of
the connectable wire cross-section, specified the
manufacturer.5 0.0 6. The
clearance distances IEC 60947-1 and IEC 60664-1 are
related it.0 6.) This applies exclusively to
terminal blocks with multiple connection levels (multi-tier
terminals) and test-disconnect terminal blocks for which
current reduction permissible.5 2.0
A 17.5 2.
Rated current IEC 60947-7-1
Test currents are assigned the rated cross-sections
according IEC 60947-7-1.
Pollution severity IEC 60947-7-1
The pollution severity defines the influence solid, liquid or
gaseous foreign matter, which may reduce the dielectric
strength the specific surface resistance.
Rated voltage IEC 60947-7-1
The rated voltage terminal block the rated insulation
voltage which the insulation tests and creepage distances
relate.5 4.3.35
CAT1 Version 2025
Installation
C
Standards and industries
