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Taken from the Govs Energy Star page For more information see;
EnergyStar
Definitions : EPA has
prepared detailed definitions of single voltage external ac-ac and ac-dc
power supplies and other related terms as relevant to ENERGY STAR.
A. External Power Supply (EPS): For the purposes of this
specification, an external power supply:
- is designed to convert line voltage ac input into lower
voltage ac or dc output;
- is able to convert to only one output voltage at a time;
- is sold with, or intended to be used with, a separate
end-use product that constitutes the primary load;
- is contained in a separate physical enclosure
1
from the end-use
product;
is connected to the end-use product via a removable or
hard-wired male/female electrical connection, cable, cord or
other wiring;
does not have batteries or battery packs that physically
attach directly (including those that are removable) to the
power supply unit;
does not have a battery chemistry or type selector switch
AND
an indicator light or state of
charge meter (e.g., a product with a type selector switch AND a
state of charge meter is excluded from this specification; a
product with only an indicator light is still covered by this
specification); and
has nameplate output power less than or equal to 250 watts.
- Ac-Ac External Power Supply:
An external ac-ac power supply
is an EPS designed to convert line voltage ac input into lower
voltage ac output.
- Ac-Dc External Power Supply:
An external ac-dc power supply
is an EPS designed to convert line voltage ac input into lower
voltage dc output.
- Low Voltage External Power Supply:
For the purposes of this
specification, a low voltage model is an EPS with a nameplate output
voltage of less than 6 volts and a nameplate output current greater
than or equal to 550 milliamps.
- Model:
An EPS that is sold or marketed under a unique model
number or marketing name. Any variation in the nameplate information
(e.g., the rated input or output voltage, amperage, or wattage),
circuitry, or output cord size is considered a unique model.
1 "Physical enclosure" refers to the housing of the products
themselves, not their retail packaging.
ENERGY STAR Program Requirements for External Power Supplies (Version
2.0) 2
2 (a) "Ln" refers to the natural logarithm. The algebraic order of
operations requires that the natural logarithm calculation be performed
first and then multiplied by 0.0626 (or 0.0750 for low voltage models),
with the resulting output added to 0.622 (or 0.561 for low voltage
models). (b) An efficiency of 0.87 or 0.86 in decimal form corresponds
to the more familiar value of 87% or 86% when expressed as a percentage.
Active Mode: The condition in which the input of a power
supply is connected to line voltage ac and the output is connected
to an ac or a dc load drawing a fraction of the power supply’s
nameplate power output greater than zero.
- No-Load Mode:
The condition in which the input of a power
supply is connected to an ac source consistent with the power
supply’s nameplate ac voltage, but the output is not connected to a
product or any other load.
- Power Factor (True):
The true power factor is the ratio of
the active, or real, power (P) consumed in watts to the apparent
power (S), drawn in volt-amperes (VA).
SP PF=
This definition of power factor includes the effect of
both distortion and displacement.
Qualifying Products:
In order to qualify as ENERGY STAR, an external power supply model
must meet the definition in Section 1.A, as well as either the
definition in 1.B or 1.C, and the specification requirements
provided in Section 3, below.
Energy-Efficiency Specifications for Qualifying Products:
Only those products in Section 2 that meet all of the
following criteria for Active Mode, No-Load Mode, and power factor
(if applicable) may qualify as ENERGY STAR.
- Active Mode
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To be eligible for ENERGY STAR qualification, an
external power supply model must meet or exceed a minimum
average efficiency for Active Mode, which varies based on the
model’s nameplate output power. Tables 1 and 2, below, outline
the equations for determining minimum average efficiency, where
P no
stands for nameplate output
power and Ln refers to the natural logarithm. Table 1 addresses
all standard EPSs, while Table 2 gives separate equations for a
subset of low voltage EPSs that meet the appropriate definition
in Section 1.D. All efficiency values shall be expressed in
decimal form and rounded to the hundredths place.
Table 1: Energy-Efficiency
Criteria for Ac-Ac and Ac-Dc External Power Supplies in Active
Mode: Standard Models
Nameplate Output Power (P no)
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Minimum Average Efficiency in Active Mode
(expressed as a decimal) 2
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0 to
≤
1 watt
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≥
0.480 * Pno
+ 0.140
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> 1 to
≤
49 watts
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≥
[0.0626 * Ln (Pno)]
+ 0.622
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> 49 watts
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≥
0.870
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