Premises Security (part 11) Power Protection and Security

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There are in-fact three major types of UPS.

• Standby
• Line Interactive
• On-line

Standby UPS
While the first variety is by far the cheapest, very rarely these days, do you see standby UPS' on sale.
This is partly because of the way a standby unit works. This type of UPS does not participate in providing power for the load AT ALL unless the mains supply goes severely over or under voltage or frequency.
At that point the load is "cut-over" from the mains supply to power supplied by the UPS from it's batteries.

In today's high speed digital electronics world, equipment doesn't take kindly to severe over or under voltage conditions. Add to that the power spikes and short (millisecond) power loss which occurs at UPS cut-over, and you have a recipe for disaster !
In the digital electronic security world this also equates to lots of false alarms and damaged equipment.

Line Interactive UPS
Bring on the Line Interactive design.
The power for the load constantly passes through a transformer which is also constantly electronically adjusted so that the output voltage never gets excessively high nor low and if the frequency starts to deviate or the voltage is outside of what can be controlled by the transformer, the UPS starts supplying its own power to the load via that same transformer so there is no actual break in supply.

These are the lower priced of the two UPS types you will typically see available today, and are often about 52c per VA (so a 1000VA will cost approximately $520)

The more expensive of the two will most likely be an on-line or "full conversion" UPS.

On-Line UPS
On-line UPS' are sometimes referred to as "full conversion" UPS'

The reason for these names is that the UPS is always 'on-line'.
The 'load' (equipment) protected by the UPS is always supplied by power generated by the UPS' electronic "inverter" circuitry thus it is "fully converted."

The way these UPS' work is that the utility power runs what is essentially a high powered battery charger circuit to keep the UPS batteries charged at all times.
The inverter in the UPS gets it's power from the batteries and from that generates a constant, smooth, noise-free source of mains electricity.

This is similar to the way "switch-mode" power supplies in sensitive electronic equipment operate to protect data and video signals from becoming corrupted.

So, back to the topic.
Our rough calculations showed we would probably want about 900W and the nearest common-value UPS will probably be a 1000VA (1kVA)

From here on it's really a matter of preference of supplier, UPS features, and how much you want to spend, as to which make and model you choose.

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