Q.E.S.
Frequently Asked Questions - Why
is there a need for Power Protection?
- What
are Harmonics?
- What
is a UPS?
- What
can a UPS do?
- What
is the difference between an Online and Offline / Standby UPS?
- What
are Gel batteries or SLA batteries?
- What
are battery ratings?
Why
is there a need for Power Protection?Over the last
20 years there has been a global explosion in demand for electricity, with national
distribution systems struggling to meet demand. This demand, along with
the increasing dependence on computerised systems, have highlighted the importance
of maintaining a continuous and high quality electrical supply. Computers,
telecommunications, industrial control systems and many other key applications
and services are dependant on power quality. Unprotected computers are subject
to electrical noise and high energy spikes, voltage or frequency variations, and
power interruptions. Power pollution will reduce the performance and shorten
the life of any system exposed to the raw mains supply Back
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What
are Harmonics?Harmonics results from distortions to the voltage
and/or current sine waves. Harmonics are commonly caused by ASDs, industrial
processes, certain electronic loads, and wiring connections. Harmonic problems
often can be corrected by filtering or resizing power system components. Back
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What is a UPS
?UPS is the abbreviation for Uninterruptible Power Supply. It is
a Power Conditioner with a Battery. By adding the battery it is possible
to offer protection against power failure or black outs. Even a UPS that
supplies power for just a few minutes is often enough to ride out power company
glitches or short outages. Back to Top
What can a UPS do?A
UPS normally performs the following functions: Absorb
relatively small power surges
Smooth
out noisy power sources
Provide
power for a period following a power blackout
Some
UPS systems provide the following additional functions: Monitor
the status of the power supply
Automatic
shutdown and restarting of equipment during long power cuts
Provide
alarms for certain error conditions
Provide
protection against short circuits
Back
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What
is the difference between an Online and Offline / Standby UPS?The
terms Online and Offline / Standby refer to the general state of the UPSs internal
inverter under normal mains conditions. Offline
UPSs are the simplest and least expensive.
When mains is present, it is routed straight through the UPS bypassing the inverter
to the output. A degree of filtering ensures limited protection against
spikes and other irregularities. The batteries are charged all the time,
but only in the event of a power failure will the load be fed by the inverter.
The switch from mains to inverter supply (generally referred to as Transfer Time)
usually takes a few milliseconds. Online
UPSs take the incoming AC mains supply and
convert it to DC which feeds the battery and the load via the inverter.
If the mains supply fails, then the batteries feed the load via the inverter with
no interruption to the output supply at all. An Online system, by nature
of the dual conversion design AC-DC / DC-AC), ensures a far higher degree of isolation
of the load from the irregularities on the mains supply. In general, Plug
N Play Online systems are more expensive than similar Offline solutions because
the inverter has to be rated for continuous operation. Back
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What
are Gel batteries or SLA batteries?Gel or Sealed
Lead Acid batteries are basically the same chemistry as a wet (flooded cell) battery.
The batteries' electrolyte is in a gelatin form and is absorbed into the plates,
and the battery is sealed with epoxies. These batteries may be used in
any position as the batteries are exceptionally leak resistant. These batteries
are used in UPS and DC Power Systems. These batteries are 2 volts per cell
so the common batteries are 4, 6 and 12 volt. Back
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What
are battery ratings?Some of the common battery ratings
are: Amp-Hour battery rating:
This is a common battery rating. Amp-hour rating of battery capacity is
calculated by multiplying the current (in amperes) by time (in hours) the current
is drawn. Amp-hour battery rating is commonly used on sealed lead acid batteries
used in UPS and DC Power Systems. For example: a battery which delivers
2 amperes for 20 hours would have a 40 amp-hour battery rating (2 X 20 = 40). Cold
Cranking Amperage battery rating:
CCA
is the discharge load in amps which a battery can sustain for 30 seconds at 0
degrees F and not fall below 1.2 volts per cell (7.2V on 12V battery). Back
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