K Series
AC-DC Converters >100 Watt
Rugged Environment
Edition 4/4.99
20/28
MELCHER
The Power Partners.
Table 13: Isolation
Characteristic
Input to
Output to Output to
Unit
case
output
case
output
Electric
Required according to
1.5
3.0 1
––
kVrms
strength
IEC/EN 60950
2.1
4.2 1
––
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
1 In accordance with IEC/EN 60950 only subassemblies are tested in factory with this voltage.
2 Tested at 100 V DC.
For creepage distances and clearances refer to:
Technical Information: Safety.
Due to high current values, all LK units provide two inter-
nally parallel connected contacts for certain paths (pins 4/6,
8/10, 26/28 and 30/32, respectively). It is recommended to
connect load and supply to both female connector pins of
each path in order to keep the voltage drop across the con-
nector pins to an absolute minimum and to not over-
stress the connector contacts if currents are higher than
approx. 8 A. The connector contacts are rated 8 A over the
whole temperature range.
Make sure that there is sufficient air flow available for con-
vection cooling. This should be verified by measuring the
case temperature when the unit is installed and operated in
the end-use application. The maximum specified case tem-
perature
TC max shall not be exceeded. See also: Thermal
Considerations.
Check for hazardous voltages before altering any connec-
tions.
Ensure that a unit failure (e.g. by an internal short-circuit)
does not result in a hazardous condition. See also:
Safety
of operator accessible output circuit.
Cleaning Agents
In order to avoid possible damage, any penetration of
cleaning fluids is to be prevented, since the power supplies
Protection Degree
Condition: Female connector fitted to the unit.
IP 30: All units except those with option P, and except
those with option D or V with potentiometer.
IP 20: All units fitted with option P, or with option D or V
with potentiometer.
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
Basic insulation between output and case based on
200 V AC and DC.
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 UL 1950 recognition limits the maximum case tem-
perature of the standard modules to
TC = TC max – 10 K =
95
°C.
The AC-DC converters are subject to manufacturing sur-
veillance in accordance with the above mentioned UL,
CSA, EN and with 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).