KP Series
AC-DC Converters >100 Watt
Rugged Environment
Edition 4/4.99
18/23
MELCHER
The Power Partners.
Table 11: Isolation
Characteristic
Input to
Output to Output to
Unit
case
output
case
output
Electric
Required according to
1.5
3.0
––
kVrms
strength
2.1
4.2
––
kV DC
test voltage
Actual factory test 1 s
2.8
5.6 1
1.4
0.14
AC test voltage equivalent
2.0
4.0 1
1.0
0.1
kVrms
to actual factory test
Insulation resistance at 500 V DC
>300
>100 2
M
For creepage distances and clearances refer to
Technical Information: Safety.
Standards and Approvals
All AC-DC converters correspond to class I equipment.
They are UL recognized according to UL 1950, UL recog-
nized for Canada to CAN/CSA C22.2 No. 950-95 and LGA
approved to IEC/EN 60950 standards.
The units have been evaluated for:
Building in
Basic insulation between input and case, based on 250 V
AC and 400 V DC
Double or reinforced insulation between input and output,
based on 250 V AC and 400 V DC
Operational insulation between output and case.
Operational insulation between output and output
The use in a pollution degree 2 environment
Connecting the input to a primary or secondary circuit
which is subject to a maximum transient rating of 2500 V
(overvoltage category III based on a 110 V primary cir-
cuit, overvoltage category II based on a 230 V primary
circuit).
The AC-DC converters are subject to manufacturing sur-
veillance in accordance with the above mentioned UL,
CSA, EN and ISO 9001 standards.
Isolation
The electric strength test is performed as factory test in ac-
cordance with IEC/EN 60950 and UL 1950 and should not
be repeated in the field. Melcher will not honour any guar-
antee claims resulting from electric strength field tests.
Important: Testing by applying AC voltages will result in
high and dangerous leakage currents flowing through
the Y-capacitors (see fig.:
Block diagram).
Leakage Currents in AC-DC operation
Leakage currents flow due to internal leakage capacitance
and RFI suppression Y-capacitors. The current values are
proportional to the mains voltage and nearly proportional to
the mains frequency and are specified at an input voltage of
254 V (50 Hz) where phase, neutral and protective earth
are correctly connected as required for class I equipment.
V
MI
500
1500
10 k
220 nF
22 nF
10061
Under test conditions the leakage current flows through a
measuring instrument (MI) as described in fig.:
Measuring
instrument for earth leakage current tests, which takes into
account impedance and sensitivity of a person touching
unearthed accessible parts. The current value is calculated
by dividing the measured voltage by 500
. If inputs of K-
units are connected in parallel, their individual leakage cur-
rents are added.
Fig. 25
Measuring instrument (MI) for earth leaking current tests
according to IEC/EN 60950.
Vo+
Vo–
N
P
10062
N
P
MI for
earth
leakage
current
Fig. 26
Test set-up
Table 12: Leakage currents
Characteristic
Class I
Unit
LKP 5000
Maximum earth
Permissible according to IEC/EN 60950
3.5
mA
leakage current
Specified value at 254 V, 50 Hz
0.82
1 In accordance with IEC/EN
60950 only subassemblies
are tested in factory with this
voltage.
2 Tested at 100 V DC.