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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Premises Security (part 10) Power Protection and Security

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An Example CalculationFollowing on from my last entry, let's work through an example of estimating your UPS size..

* Your security panel is a wireless model.
* It does not support the addition of external batteries.
* It has an internal backup battery which is stated to support the system for 2 hours.

Note; unless otherwise advised, the battery spec is always based on new batteries.

Battery LifeAll rechargeable batteries loose their ability to support load as they age, regardless of whether they are kept "fully charged" or not.
Depending on the type* of battery, this decline will start to become apparent any time from about 2~3 years onward and accelerates each year thereafter.

For example, a Sealed Lead Acid (SLA) battery will be nearing end-of-life after about 4~6 years

* Your panel has an external power-pack which has a rated output of 12V 1.5A.
Volts x Amps = Watts so 12x1.5=18W

Now it is entirely unlikely that your system will actually draw this much power, but if you can't find the rating visible anywhere on the system and don't have a manual which lists those specs, then run with the above as a rough estimation.

Decide Your "Run-time"Now let's say you want to be assured that your system will operate for a full 24hrs without electricity.

Again using VERY rough calculations, 18W x24hrs = 432W required.
Build in a value for Power Factor of 0.04 and you'll need approx 450W.

Remember too that the batteries will start to loose their capacity after the first couple of years so build in some redundancy there too.
My rule-of-thumb is either double or at-least half as much again as your calculated requirements.

Given that we're talking about a very small UPS in this example, let's double our requirements so 450W x2 or 900W.

Now it's shopping time.

Preferred UPS Brands
Although there are many brands of UPS on the market, my experience of selling, installing, servicing and refurbishing power security devices such as these, has led me to favor three brands.
Powerware, APC, Emmerson.

Although you could now break-out the search-engine and do some research, searching for "UPS" can be somewhat frustrating, as that sequence of letters is used by a lot of NON-electronics related companies. (Eg. United Postal Service)
Probably the easier way to start your research is to select from some of the ads you'll find in this blog

Common RatingsAs you do your research, you'll find that UPS' come in "common ratings"
Typically these are;
100;150;300;500;1000;1500;1750~1800;2000~2200,3000;5000VA and upward.

Two Price Scales
You might also notice that there are two different price ranges for roughly the same VA ratings. For example one 2200VA may be $1600 yet another 2000VA may be $2500! Why?
Because there are different types of UPS.

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Premises Security (part 9) Non-video surveillance

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In summary to-date
Part 1 discussed the different types of security systems.
Part 2 explained the differences between Local and Monitored alarms and Perimeter vs. State-change detection along with a look at some different video security surveillance cameras.
Part 3 looked at wireless vs. wired security systems.
Part 4 looked at setting up a video security installation
Part 5 covered remote monitoring of the video installation and security risks associated with that. It also considered using Motion Detection.
Part 6 Began an overview of NON-video surveillance devices.
It covered;
The “closed loop”, Micro/Magnetic-Reed/Thermatic & Pressure Mat switches
Part 7 Continued the overview of NON-video surveillance devices.
It covered detection of environment change rather than physical switch operation
It considered;
Pulsed Infra-red beams, Passive Infra-red (PIR) movement detectors, Proximity detection
Part 8 Completed the overview of NON-video surveillance devices.
We considered that security is more than just Intruder Detection so then looked at Temperature and Light/Darkness security sensors such as;
Thermal Fuses, Thermistor or semiconductor temperature monitors, LDR or Semiconductor light sensors.
And so to Part #9 of the series where we return to finish considering the two points raised in Part #1 of this series.

The first point was the trade-off of cost & size vs functionality, risk and aesthetics which led into the discussion of the various types of security system and the devices used (Parts #2 thru #8)
The second point was the possibility of having the "best of both" in a small easily installed surveillance system AND extended power coverage by use of a "UPS" for power assurance.

Let's now look at this second point.
The Trade-off

As I stated in Part #1, there is often a trade-off by the manufacturers of Digital Security systems, between size, cost and reliability. To keep size and cost down, battery capacity is minimised. Which is fine for 80-90% of the time.
We often have short-term power outtages of less than 2 hours and the supplied internal backup batteries work just fine.

Impact on Wireless Installations

In a wireless based security installation it is much less of a problem since the sensors all have their own battery power and are designed to operate 24x7 for many months on a new set of batteries.

Impact on Wired Installations

In a wired installation the sensors often source their power from the security control panel. If that is not the case then they derive their power directly from the mains supply.
In either of these scenarios, an extended loss of power supply can potentially render the system either totally inoperative or partially compromised.

Wireless or Central-Power Solution

If the system is wireless or all detectors source their power from the central panel, overcoming this weakness is relatively straightforward.
There are at-least two ways in which this can be addressed. Unfortunately both are quite bulky solutions sinc they both require the use of additional batteries.

1. Using Battery Extender Packs

If the system supports, or can be easily adapted to support, an external battery pack, then this is by far the cheapest, easiest and most efficient solution.
Essentially all that is required is some form of well-ventilated and secure housing for the desired quantity and capacity of batteries.

Technical Considerations

Technically you will need to consider the distance from the additional batteries to the security panel because of voltage loss over longer runs of wire. You will also need to stay within the manufacturer's specification for their battery charging circuitry.

Physical Considerations

The housing should be of sturdy construction capable of inhibiting fire and containing any possible battery explosion or leakage of battery acid.
Because batteries under charge give off explosive gases, the housing also needs to be well ventilated.

2. Using UPS Power Security

If your security system does NOT allow for attachment of additional battery capacity, an alternative may be to run the system off a UPS.

A UPS or Uninterruptible Power Supply generates utility-grade power (in many cases of superior quality) in the event of loss of supply to the premises.

UPS Ratings

UPS' come in all shapes and sizes and are rated in VA or Volt Amp units.
This measure is roughly equivalent to Watts which is the rating more commonly found on household appliances.

For the more technical readers, the VA rating takes into consideration Power Factor efficiency so the VA rating will always be higher than the Wattage rating (eg. a 1500VA UPS will deliver about 1200W)

Units start as small as 150VA but these are primarily designed to provide only a couple of minutes run-time on battery, sufficient only to automatically shutdown a small computer.

Calculating Your UPS Capacity

To calculate the UPS capacity required to support a system, an approximation can be made by taking the current draw of the system (either rated value or measured draw) then deciding how long you want the system to operate.

In the next installment, I'll work through an example calculation as we consider required run-time, battery life, and the different types of UPS.

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