Like most IT products, UPS too, to a large extent, has
evolved into a volume business. The entry-level and mid-range UPSs are today
pushed by the channel in the SOHO and SME segment. While selling UPSs is a
profitable business, if partners have an in-depth idea about the technicalities
involved, selling would become that much easier.
It is also advisable to be aware of the various power-related
problems and requirements. Because ultimately, this is what will determine the
type and rating of UPS that he/she will be able to sell.
WHY UPSs REQUIRED?
There are many types of disturbances in electricity, beside power cuts, that
may damage one’s computer equipments. These disturbances may be in the form of
surge, spike, sag, frequency variation, harmonic distortion or noise.
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While surge is a sudden increase in the main voltage which
usually lasts for 1/20th of a second, spikes are caused by lightening strikes,
or when utility power comes back after a failure.
A sag refers to a dip in the main voltage. If this sag lasts
for more than one minute its called a brownout. Brownouts occur when heavy
machineries are turned on.
Different countries have different standard mains frequency.
For India, it is fixed at 50 Hz. Any deviation from this frequency can cause
damage to computer equipments.
The main voltage is in the form of a sinusoidal waveform.
When there are distortions in these waveforms it’s referred to as harmonic
distortion. And finally, there is noise which is often generated by normal
computer operation.
While it is essential to find out what kind of disturbances
affect one’s power circuitry, this information is also critical for
determining the kind of UPS required for corrective action. Since most UPS
ratings are in VA (which refers to the apparent power), you must know the actual
power consumed by your equipments before going in for a particular rating of
UPS.
This actual power when divided by power factor (a factor of
0.7 is considered to be good enough) gives the desired VA rating of UPS to be
installed. Simply put, apparent power (VA) = actual power (watts)/power factor.
However, identifying the rating of the required UPS is not
the final answer. It is here that one must understand that there are three basic
UPS technologies: off-line, line-interactive and on-line.
SELLING THE RIGHT UPS
An off-line UPS, also referred to as a standby UPS, can prove to be an ideal
choice for environments which have less critical and stand-alone applications
like isolated PCs and peripherals. Though these UPSs can be connected to a
network, they usually do not have provisions for network communications.
Line-interactive technologies allow options of network communication.
A line-interactive UPS provides a highly effective power
conditioning in addition to a back-up. Different UPSs may offer a range of
back-up times. Such UPSs are useful in environments where instances of power
outages are few but power fluctuations are common.
For environments requiring the highest level of network power
protection, conditioning and back-up, on-line technology is the best. On-line
UPSs also provide frequency regulation which is essential for use with back-up
generator systems.
ON-LINE OR OFF-LINE?
UPSs switch to battery to prevent glitches. It is also capable of protecting
machines from most power spikes by clamping down on excess voltage. This helps
take care of more than 90 percent of all power outages.
However, on the flip-side, off-line UPSs offer little
protection from sags and surges and nil protection from harmonic distortions and
frequency variations.
A line-interactive UPS goes beyond offering mere battery
back-up to provide control over power fluctuations. The critical advantage of
line-interactive UPS is the voltage boost circuitry and the range of input
voltage that the unit accepts. An ideal line-interactive UPS is one which
provides boost to at least 25 percent below standard voltage before switching to
battery back-up.
The quality of power from an on-line UPS is better than
off-line and line-interactive type. While the latter two reduce the impact of
spikes, surges and sags by boosting power or switching to battery back-up, the
on-line completely regenerates the waveforms.
UPS and |
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Network Problems |
Possible |
Offline UPS Protection |
Line Interactive UPS Protection |
OnLine UPS Protection |
|
Network hanging |
Power outage Power Interruption |
80% | 90% | 100% | |
Harmonic distortions Distortions that occur at multiples of fundamental wave |
0% | 0% | 100% | ||
Hardware damage (SMPS burnout, motherboard failure) |
Voltage surges Brief intense surges of voltages of 100% or more above normal. |
50% | 50% | 100% | |
Modem malfunction (reduced speed, frequent transfer to self check mode) |
Frequency variations Fluctuations in number of cycles per second |
0% | 0% | 100% | |
System hanging, keyboard lockup, monitor malifunction |
Voltage sags and swells short term low and high voltage of the order of +10% |
50% | 100% | 100% | |
Electrical noise, unwanted electrical interferences |
90% | 95% | 100% | ||
Unintended server shutdown on DG startup |
UPS non-compatible with DG set |
Non Compatible |
Non Compatible |
Fully Compatible |
In case of off-line and line-interactive, most of the power
fluctuations are left un-rectified. On-line UPSs also provide frequency
regulation and control harmonic distortions which are essential for use with
back-up generator systems.
The bottomline is, whatever be the technology, partners
should first understand the nature of power discrepancies, assess the consumer’s
power requirement and then accordingly suggest the kind of UPS with a rating
that best addresses the user’s needs.
GOLDIE in Mumbai