Brochure/Catalogue

Electrical data
Rated impulse withstand voltage
The rated impulse withstand voltage is
derived from:
• Voltage conductor – earth
(the rated voltage of the network,
taking into account all networks)
• Surge category
Surge categories
are stipulated in accordance with the
German standard DIN VDE 0110-1 (for
electrical equipment fed directly from
the low-voltage network).
Surge category I
• Equipment that is intended to
be connected to the permanent
electrical installation of a building.
Measures to limit transient surges
to the specic level are taken
outside the equipment, either in the
permanent installation or between
the permanent installation and the
equipment.
Surge category II
• Equipment to be connected to the
permanent electrical installation of a
building, e.g. household appliances,
portable tools, etc.
Surge category III
• Equipment that is part of the
permanent electrical installation
and other equipment where a
higher degree of availability is
expected, e.g. distribution boards,
circuit-breakers, wiring systems
(including cables, busbars, junction
boxes, switches, power sockets)
in the permanent installation,
and equipment for industrial use
and some other equipment, e.g.
stationary motors with permanent
connections to the permanent
installation.
Surge category IV
• Equipment for use at or near the
power supplies in the electrical
installations of buildings, between
the principal distribution and the
mains, e.g. electricity meters, circuit-
breakers and centralised ripple
controllers.
Pollution severity categories
Pollution severity category 1
• No pollution, or only dry, non-
conductive pollution that has no
inuence.
Pollution severity category 2
•
Non-conductive pollution only;
occasional condensation may cause
temporary conductivity.
Pollution severity category 3
• Conductive pollution, or dry, non-
conductive pollution that is liable
to be rendered conductive through
condensation.
Pollution severity category 4
• Contamination results in constant
conductivity, e.g. caused by
conductive dust, rain or snow.
Unless explicitly stated otherwise, the
measurement of clearance and
creepage distances and the resulting
rating data for electromechanical
components is based on pollution
severity 2 and surge category III, taking
account of all network types.
Design of clearance and creepage distances
in electrical equipment – inuencing factors
Table 1: Rated impulse withstand voltages for electrical equipment
Rated voltage of power
supplies system *) in V
Rated impulse withstand voltage in kV
Three-
phase
systems
Single-phase
systems with
neutral point
Electrical equipment at
the supplies point of the
installation
(Surge
category IV)
Electrical equipment as
part of the permanent
installation
(Surge
category III)
Electrical equipment
to be connected to the
permanent installation
(Surge
category II)
Specially protected electrical
equipment
(Surge
category I)
120 to 240 4.00 2.50 1.50 0.80
230/400
277/480 6.00 4.00 2.50 1.50
400/690 8.00 6.00 4.00 2.50
1000 Values depend on the particular project of, if no values are available, the values of thepreceding line apply.
*) to IEC 38
W
Technical appendix/Glossary
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