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ERP2U Power Supply Design Guide, V2.31
- 13 -
AC line shall not cause damage to the power supply. In the case of redundant AC inputs, the AC line dropout
may occur on either or both AC inlet.
5.7 AC Line Fuse
STATUS
Required
The power supply shall incorporate one input fuse on the LINE side for input over-current protection to prevent
damage to the power supply and meet product safety requirements. Fuses should be slow blow type or
equivalent to prevent nuisance trips. AC inrush current shall not cause the AC line fuse to blow under any
conditions. All protection circuits in the power supply shall not cause the AC fuse to blow unless a component in
the power supply has failed. This includes DC output load short conditions.
5.8 AC Inrush
STATUS
Required
The power supply must meet inrush requirements for any rated AC voltage, during turn on at any phase of AC
voltage, during a single cycle AC dropout condition, during repetitive ON/OFF cycling of AC, and over the
specified temperature range (T
op
). The peak inrush current shall be less than the ratings of its critical components
(including input fuse, bulk rectifiers, and surge limiting device).
STATUS
Recommended
An additional inrush current limit is recommended for some system applications that require multiple systems on a
single AC circuit. AC line inrush current shall not exceed 40 A peak. After one-quarter of the AC cycle, the input
current should be no more than the specified maximum input current from
Table 3.
5.9 AC Line Transient Specification
STATUS
Recommended
AC line transient conditions shall be defined as “sag” and “surge” conditions. Sag conditions (also referred to as
“brownout” conditions) will be defined as the AC line voltage dropping below nominal voltage. Surge conditions
will be defined as the AC line voltage rising above nominal voltage.
The power supply shall meet the requirements under the following AC line sag and surge conditions.
Table 5: AC Line Sag Transient Performance
AC Line Sag
Duration Sag Operating AC Voltage Line Frequency Performance Criteria
Continuous 10% Nominal AC Voltage ranges 50/60 Hz No loss of function or performance
0 to 1 AC
cycle
100% Nominal AC Voltage ranges 50/60 Hz No loss of function or performance
>1 AC cycle >10% Nominal AC Voltage ranges 50/60 Hz Loss of function acceptable, self