CONVERSION TECHNOLOGY
Double Conversion
Double Conversion
refers to a UPS that converts AC to DC and then back to AC. The
inverter of this UPS system continuously carries the load; as such, it
is sometimes called a true on-line UPS. You can configure all static
UPS technologies as double-conversion systems.
Advantages of double-conversion include:
- Superior voltage and frequency regulation at the UPS output,
- Isolation of the load from the utility source, and
- Quarter-cycle transfer capability with the use of a static transfer switch in the event of UPS failure.
Disadvantages, compared to other topologies, include:
- Lower efficiency and
- Greater heat dissipation.
Single-Conversion
Single-Conversion"
refers to the single AC-to-AC conversion normally seen by the load. For
example, input to the UPS passes only through an isolation transformer,
regulating transformer, or filter. To bring the standby UPS components
on-line, an abnormal condition must exist.
There are a variety
of single-conversion topologies, including line-interactive and
tri-port configurations. In a line-interactive system, the inverter
interacts with the line to buck, boost, or replace incoming power on an
as-needed basis. The inverter may either operate continuously or switch
on by control logic.
A tri-port system
is similar, but is always on line. The utility power normally passes
through an isolation transformer and filter or a regulating
(ferroresonant) transformer.
Advantages of a single-conversion system
include:
|
|
Increased
efficiency and |
Lower
heat loss.
|
| Disadvantages
include: |
| Inferior voltage and frequency regulation,
and |
| Possible complete interruption
of power to the load upon loss of normal AC input. |
| An off-line UPS
operates only when it detects loss of the normal utility
source to the load. Advantages of the off-line UPS are:
|
| Increased efficiency and |
| Lower heat loss. |
| Disadvantages
include: |
| Certain interruption of power to the
load due to the loss of the normal source and |
| The possibility of standby equipment
failing to operate properly. |
| Pulse-width
modulation (PWM), is being used as a inverter Technology |
Pulse-Width Modulation
This type converts
DC to AC by using power switching at a 20 kHz to 50 kHz rate. A linear
feedback loop is part of the circuitry. The output is a pulse-width
modulated positive and negative square wave. A simple output low-pass
filter removes the high frequency carrier for a smoothed sine wave.
Harmonic Distortion
There are two
harmonic distortions associated with UPS systems. One is the UPS'
ability to minimize the amount of harmonic distortion caused by the
UPS-fed loads. The other is the amount of harmonic distortion the UPS
reflects back onto the distribution source that's providing its input.
This second characteristic affects the power quality of other loads.
Input filters can
mitigate reflected harmonics at the UPS input. Step-wave and PWM
systems have greater sensitivity to load-generated harmonic distortion
than other types of UPS systems. Sometimes, you must derate the system
capacity to compensate for load profiles with a high crest factor (the
ratio between the peak of the current waveform and its rms value).
Automatic Sense Intellegent Control (ASIC)
Battery Level Auto
Sense Charging : Boost Level Charging :Batteries are charged at maximum
allowed continuous constant charging current till it achieve the
battery boost voltage level of 14.4V. or up to the automatic battery
set by control unit itself. The control Unit check the battery level at
specified interval of time when the battery level stop increasing then
it lock that battery level as a Boost level maintain this for the four
months. It recycle the same process of battery level sensing in four
month cycle.
Trickle Level
Charging : To maintain the float level, the charge reset to zero
current at 13.7V for some times and start again with pulse charging of
<1AMP current at same voltage. This keeps the battery in full charge
condition even when not in use.
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