LOK4000 Datasheet, PDF (5/12 Pages) Power-One – DIN-Rail Mountable AC-DC (DC-DC) Converters

LOS, LOR, LOK4000 Series Data Sheet
DIN-Rail Mountable AC-DC (DC-DC) Converters
Thermal Considerations
If an AC-DC converter is located in free, quasi-stationary air
(convection cooling) at the indicated maximum ambient
temperature T_{A max} (see table: Temperature specifications) and
is operated at its nominal input voltage and output power, the
temperature measured at the Measuring point of case
temperature T_C (see Mechanical Data) will approach the
indicated value T_{C max} after the warm-up phase. However, the
relationship between T_A and T_C depends heavily on the
conditions of operation and integration into a system. The
thermal conditions are influenced by input voltage, output
current, airflow, temperature of surrounding components and
surfaces. T_{A max} is therefore, contrary to T_{C max}, an indicative
value only.
The relation between the maximum allowed output power
P_{o allowed} and the temperature T_A of the surrounding air is given
in the figure below. The rates apply if the AC-DC converter is
located in free, quasi-stationary air (convection cooling).
Note: Sufficient forced cooling allows T_A to be higher than the
value given in the table if T_{C max} according to the table is not
exceeded.
Caution: The installer must ensure that under all operating
conditions T_C remains within the limits that are stated in the table
Temperature specifications.
P_{o allowed}/P_{o nom}
1.0
0.5
0.45
0
T_A
–10 0 10 20 30 40 50 60 70 °C
Fig. 4
Maximum allowed output power versus ambient temperature
at V_i >105 VAC for LOK models.
Output Power at Low Input Voltage
The output power of LOK models must be derated at low input
voltage, see figure below.
P_{o allowed}/P_{o nom}
1.0
0.85
0.5
0
V_i
50 75 100 125 150 175 200 225 250 275 300 VAC
Fig. 3
Maximum allowed output power versus input voltage at
T_A 50°C. for LOK models.
Output Protection
Battery charger versions LOK4140-, 4240-, LOK4740-2RLD,
and the LOK4001-2RLD have a rectangular current limitation
characteristic, which limits the output current to within 100 and
150% of I_{o nom}. The other models are protected against
overload by a current limiting circuit, which shuts down the
converter in overload condition. It automatically restarts after
removal of the overload condition (hiccup mode).
All models are short-circuit and no-load proof.
Outputs Connected in Series
Two or more converters supplying the same or different output
voltages may be connected in series. The value of the
maximum output current to be taken is defined by that unit
providing the lowest current limiting value. It should be assured
that the outputs do not feed backwards into each other caused
by their different rise/fall times at switch-on/off cycles by adding
reverse polarity diodes across each output.
Parallel Operation
Only possible with battery charger versions.
The outputs of several battery charger models with equal
output voltage (e.g. several LOK4240-2RLD) may be
connected in parallel.
SEP 09, 2005 revised to JUL 17, 2006
Page 5 of 12
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