Download UPS Key Product Criteria The ENERGY STAR specification for

UPS Key Product Criteria
The ENERGY STAR specification for UPSs establishes minimum average efficiencies for UPSs of
different:
Input dependency characteristics -- Voltage and Frequency Dependent (VFD), Voltage Independent
(VI), and Voltage and Frequency Independent (VFI).
Rated Output Power- from less than 1500 kVA to greater than 10,000 kVA.
Load Profiles – assume profiles at 25%, 50%, 75%, and 100% load.
The key criteria are shown below for AC-output UPSs that operate in a single input dependency (i.e.,
VFD, VI or VFI). Additional criteria for UPSs that can operate in multi-mode (e.g., VFD and VFI) and
DC-output UPCs/Rectifiers used in telecommunications can be found in Sections 3.2.2 – 3.2.3 and
Section 3.3 of the Version 1.0 of the UPS Program Requirements
(357KB), respectively.
Calculation of Average Efficiency for Ac-output UPSs
EffAVG = t25% x Eff25% + t50% x Eff50%+ t75% x Eff75% + t100% x Eff100%
Where:
EffAVG is the average loading-adjusted efficiency,
tn% is the proportion of time spent at the particular n% of the Reference Test Load, as specified in the
loading assumptions in Table 1, and
Effn% is the efficiency at the particular n% of the Reference Test Load, as measured according to the
ENERGY STAR Test Method.
Table 1: Ac-output UPS Loading Assumptions for Calculating Average
Efficiency
Rated Output
Input Dependency
Proportion of Time Spent at Specified
Power, P, in watts
Characteristic*
Proportion of Reference Test Load, tn%
(W)
25%
P ≤ 1500 W
1500 W <P ≤
10,000 W
50%
75%
100%
VFD
0.2
0.2
0.3
0.3
VI or VFI
0
0.3
0.4
0.3
VFD, VI, or VFI
0
0.3
0.4
0.3
P > 10,000 W
VFD, VI, or VFI
0.25
0.5
0.25
0
*See information below about input dependency characteristic
Table 2: Ac-output UPS Minimum Average Efficiency Requirement
Minimum Average Efficiency Requirement (EffAVG_MIN), where:
P is the Rated Output Power in watts (W), and
ln is the natural logarithm.
Rated Output Power
Input Dependency Characteristic
VFD
VI
P ≤ 1500 W
0.967
1500 W <P ≤ 10,000 W
0.97
0.967
P > 10,000 W
0.97
0.95
VFI
0.0099 X ln (P) +0.815
0.0099 X ln (P) +0.805
Table 3: Ac-output UPS Minimum Average Efficiency Requirement for
Products with Metering and Communications Capability
Minimum Average Efficiency Requirement (EffAVG_MIN), where:
P is the Rated Output Power in watts (W), and
ln is the natural logarithm.
Rated Output Power
Input Dependency Characteristic
VFD
P > 10,000 W
0.96
VI
0.94
VFI
0.0099 X ln (P) +0.795
In addition to these criteria, all AC-output VI and VFI UPSs at 100 % load must have a minimum power
factor of 90%.
Information About Input Dependency Characteristics
Also known as “passive” or “offline” or “standby” UPSs, Voltage and Frequency Dependent (VFD)
UPSs are capable of protecting the load from power outages. Typically in sizes up 1500 VA, they are
used for small offices, personal home computers and other less critical applications to provide surge
protection and battery backup. During normal use, the mains feed the load directly and also power a
rectifier (AC to DC) to charge the battery. During a power outage, battery power through an inverter (DC
to AC) feeds the load. This type of UPS cannot correct for voltage fluctuations which may cause switches
to battery power during low main voltage and drain the battery.
Also known as “line-interactive” UPSs, Voltage Independent (VI) UPSs are capable of protecting the
load from power outages and provide additional corrective voltage functions. Typically in sizes up to
5,000 VA, they are used commonly for small business, Web, and departmental servers. They also
normally draw directly from the mains and switch to battery during an outage. They are equipped with
multi-tap variable-voltage autotransformers that keep output voltages within an allowed tolerance during
low and high main voltages and eliminate battery drain during low main voltage.
Also known as “online,” “continuous” or “double conversion” UPSs, Voltage and Frequency
Independent (VFI) UPSs are capable of protecting the load against adverse effects of voltage and
frequency variations without depleting the stored energy source. They typically come in sizes up to 1,000
kVA and are used in data centers. Under normal operation, the line power is run through a rectifier (AC to
DC power conversion) to the batteries, which then powers equipment through an inverter (DC to AC
power) – which is why VFI UPSs are sometimes called “double conversion” UPSs. Filters and fast
regulating circuits in the converters isolate the load from voltage and frequency variation from the mains.
With this configuration, there is no transfer time in the event of a power failure as the power is supplied
continuously to the equipment through the battery.