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A.23
A
Overview
HDC
Technical data
Influencing factors:
Rated impulse withstand voltage
The rated impulse withstand voltage is
derived from:
Phase-to-ground voltage (the
nominal voltage of the network,
taking all networks into account)
Surge category
The surge categories are defined
in accordance with international standard
DIN EN 60664-1 (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 specific
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 and similar loads.
Surge category III
equipment that is part of the perma-
nent electrical installation and other
equipment where a higher degree of
availability is expected e.g. distribution
boards, circuit-breakers, wiring
systems (IEV 826-06-01, 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
Equiment for use at or in the proximity
of the incoming supply point of the
electrical installations of buildings
upstream of the main distribution board
e.g. electricity meters, circuit-breakers
and ripple control units.
Nominal voltage of power
supply systems
[V]
for conductor-cond. insulat.
for conductor-ground insulation
all Systems
[V]
3-phase 4-conductor systems
with grounded neutral cond. [V]
3-phase 4-conductor systems
ungrounded or cond. grounded [V]
Table 1: Three-phase 4 or 3-conductor a.c. systems
Pollution severity categories:
Pollution severity category 1
No pollution, or only dry, non-
conductive pollution that has no
influence.
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 conduc-
tive dust, rain or snow.
The dimensioning of clearances and
creepage distances, and hence the
rating data for electromechanical
products (terminals, terminal strips,
PCB terminals and plug-in connectors)
is based on pollution severity 3 and
surge category III, taking account of all
network types.
60
63
32
63
110
120
125
80
125
127
150
160
–
160
208
200
125
200
220
230
250
160
250
240
300
320
–
320
380
400
250
400
415
440
500
250
500
480
500
320
500
575
630
400
630
600
630
–
630
660
690
630
400
630
720
830
800
500
800
960
1000
630
1000
–
1000