For multi-output converters, the main output is typically a fully regulated output. If the end
application requires critical regulation on the auxiliary output(s), a linear regulator or other
regular should be added after the converter. (Note: Some MORNSUN converters have built in
linear regulators; please contact our Technical Department for details).
3. AC-DC Converter Safety Related Design Notes
3.1 Marking Requirements
Wherever, there are fuses, protective grounds, or switches, clear symbols should be indicated
according safety standards. Touchable dangerous high voltage and energy sources should be
marked with
“Caution!”
indications.
3.2 Input Cable Requirements:
Input cables of L, N and E should be brown, blue and yellow/green cables, respectively.
Ensure that the ground cable (yellow & green cable) of Type I devices (those that rely on
basic insulation and protection ground to avoid electric shock) are securely connected to the
ground, and the earth resistance is lower than
0.1Ω
3.3 Clearance and Creepage
For Type I devices, ensure:
♦
L and N are in front of the fuse.
♦
The clearance distance between the input and the metal case is above 2mm and
creepage is above 2.5mm.
For Type II devices (those that rely on strengthened insulation or double insulation to avoid
electric shock) ensure:
♦
L and N are in front of the fuse
♦
The clearance distance between the input and the metal case is above 2mm and
creepage is above 2.5mm.
♦
The clearance between the input and the metal case or SELV is above 4mm, and
creepage of that is above 5mm.
3.4 Input energy
If the input capacitor is large, a discharge resistor may be added to ensure that, after
disconnect, the voltage held between Input L, N, and the protective ground will be discharged to
37% of its maximum value or below. In Figure 2, R1 is the discharge resistor.
4. Heat Dissipation in AC/DC Converter Module Applications
Trends toward higher density in AC/DC module designs make heat dissipation an important
concern. The effect of heat on the electrolytic capacitor is of particular concern, as the life of
such capacitors can be drastically reduced when operated in a constant high temperature
environment, leading to a higher potential for failure. Proper handling of heat will increase the
life of the converter and surrounding components, thus lowering risk of failures. Some
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