Shenzhen Hpmont Technology Co., Ltd.
Chapter 1 Safety Information and Precautions
HD31 Series User Manual V1.1
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Capacitor energy storage
When the AC power supply is cut off, capacitor of HD31 sustains deadly power for a while. So to
disassemble HD31 that is powered, please cut off the AC power supply for more than 10 minutes,
confirm the internal charge indicator is off and the voltage between (+) and (-) of the main circuit
terminals is below 36V.
Generally, the internal circuit enables the capacitor to discharge. However, the discharging may fail in
some exceptions. In these cases, users need to consult Hpmont or our regional distributor.
Lightning surge protection
HD31 internal design has lightning surge overcurrent protection circuit, and has certain self-protection
capacity against the lightning.
Altitude and derating
In area where altitude exceeds 1000 meters, HD31 should be derating since the heatsink efficiency will
be reduced because of the tenuous air.
The rated value of output current derates by 1% for each 100m increase of the altitude. I.e. for the
altitude of 4000m, derated rate is 30% for rated current of HD31. Figure 1–1 is the derating curve of
rated current and the altitude.
Figure 1–1 Derating curve of rated current and altitude
70%
100%
1000m
4000m
Altitude
Rated current of HD31
1