86
Low Voltage Switch Gear
Appendix
Note 1:
If the switching device has a making and/or breaking capacity, the figures for the current and the power factor (time constants) must be stated by the manufacturer.
2:
A: frequent operation, B: infrequent operation.
Protection against electrical shock, to IEC 536
IEC 536 covers the setting up of electrical apparatus, and its
arrangement in electrical installations with rated voltages up to 1000
VAC and 1500 VDC, with regard to protection against direct contact
where operating elements such as push-buttons and switches are
located in the vicinity of live parts.
“Finger-proofing” relates only to the operating device, and only in the
normal direction of operation. A clearance of at least 30 mm radius
from the centre point of the device to any live parts, must be ensured.
The IP 20 degree of protection is superior to “finger-proofing” in that
it embodies protection against contact with electrical apparatus in
any direction. Devices which are “finger-proof” and of IP 00 degree of
protection can be provided with further protection against contact in
the form of shrouding, if so desired.
Damp heat, constant, to IEC 68 Part 2-3
In this test, the effects of a constant high level of humidity
(93 +2/-3%) and a constant temperature (40 ±2)°C over a prescribed
duration, are observed.
Damp heat, cyclic, to IEC 68 Part 2 - 30, Test Db
This test is used to assess the suitability of electrical products for
operation and storage at high relative humidity levels, in conjunction
with cyclic temperature fluctuation. A test cycle consists of 12 hours
at 40 ±2°C, with relative humidity of 93 ±3%, and 12 hours at
25 ±3°C, with the relative humidity of at least 95%.
Ambient temperature
Ambient temperature is the temperature of the room (e.g. factory bay
or switchgear room), in which the open or enclosed device is
installed, a prerequisite being that this temperature is not significantly
influenced by the heat losses from the device.
AC-23
A(B)
2
Switching of motor loads or other highly inductive
loads
All values
1
1
0.65
1
1
0.65
I
e
≤
100
I
e
>
100
10
10
1.05
1.05
0.45
0.35
8
8
1.05
1.05
0.45
0.35
I
e
A
I
-
I
e
U
-
U
e
L/R
ms
I
c
-
I
e
U
r
-
U
e
L/R
ms
I
e
A
I
-
I
e
U
-
U
e
L/R
ms
I
c
-
I
e
U
r
-
U
e
L/R
ms
DC
DC-20
A(B)
2
Connecting and disconnecting under no-load condi-
tions
All values
1
)
1
)
1
)
1
)
1
)
1
)
All values
1
)
1.05
1
)
1
)
1.05
1
)
DC-21
A(B)
2
Switching of resistive loads, including moderate
overloads
All values
1
1
1
1
1
1
All values
1.5
1.05
1
1.5
1.05
1
DC-22
A(B)
2
Switching of mixed resistive and inductive loads, in-
cluding moderate overloads (e.g. shunt motors)
All values
1
1
2
1
1
2
All values
4
1.05
2.5
4
1.05
2.5
DC-23
A(B)
2
Switching of highly inductive loads (e.g. series mo-
tors)
All values
1
1
7.5
1
1
7.5
All values
4
1.05
15
4
1.05
15
Utilization categories
for switches, disconnectors, switch-disconnectors, and fuse combination units to IEC 947-3 and EN 60947
Type of
current
Utilization
category
Typical applications
I = current made, I
c
= current broken
I
e
= rated operational current
U = voltage before make
U
e
= rated operational voltage
U
r
= recovery voltage
Verification of electrical endurance
Verification of switching capacity
Make
Break
Make
Break
I
e
A
I
-
I
e
U
-
U
e
cos
ϕ
I
c
-
I
e
U
r
-
U
e
cos
ϕ
I
e
A
I
-
I
e
U
-
U
e
cos
ϕ
I
c
-
I
e
U
r
-
U
e
cos
ϕ
