The alarm and access panels, work with DC voltages (direct current) and traditionally have had within their control panels, the presence of a battery bank, which allow through the direct UPS (Uninterruptible Power Supply Systems) the continuity in the operation of the equipment when there are failures in the electrical fluid.
By Germán Alexis Cortés H.*
However, some subsystems such as video surveillance, and in general most equipment in the main control room, are not protected against this eventuality. The same happens with computers and servers that are outside the control room, as well as with some equipment of the system of support to searches and surveillance of articles.
Under the premise that we cannot sell or install an "insecure" security system; we must ensure that the energy from which electronic security resources are released must be continuous, reliable and clean. We can understand that ALL active devices that are part of a security system must be energized through an uninterrupted power system, called UPS (Uninterruptible Power Supply), to ensure their correct operation. It is the core component of any well-designed power protection architecture.
The conclusion is obvious: we should always include the UPS item in an economic offer.
The reality, however, is that we rarely offer the UPS. Some integrators believe that this does not correspond to them; others have no suppliers; others do not even know about the subject and in many cases it is the same end users who oppose buying it. Sometimes because they already have one, at other times they think that since the basic equipment works without it, then it is not necessary or their presence is considered a luxury. With sadness I perceive, that electrical protections become a secondary accessory.
But there is nothing more important to a security system than its own safety. Variations, discharges and cuts of the electrical fluid are not only inevitable but are capable of damaging valuable equipment and putting at risk the entire safety scheme. Prepare for the worst: ...crime knows it.
Designing, planning and implementing a robust power protection solution is absolutely vital; it is part of the electrical protections, which we have talked about on other occasions.
Do not allow it to be left to buy later; we all know that there is nothing more permanent than what we call temporary. So my recommendation is to always acquire a UPS for the security system, within the first phase of any security installation with technological means.
But be careful, not just any UPS works, some recommendations to keep in mind are:
1. Exclusivity
The UPS must be exclusive to support the energy required by the devices that make up the electronic security system (CCTV, alarms and access, among others).
They should not be shared with other traditional subsystems, such as to power regulated sockets used in laboratories or the base energy for workstations and other computer equipment. Nor should it be the same UPS of the Data Center, nor that of the active telephony or networking equipment. In each case the requirements, expansion capacities and loads may be different.
If a UPS already exists on site, a separate UPS must be placed for Electronic Security. If there is a UPS that provides total replacement to the building, it must be verified that it is of the appropriate type, with the necessary power and autonomy, including expansions. Even so, in many cases it is better for manageability and security, use an additional lower capacity, exclusive for security, this provides redundancy and autonomy.
In the case of connecting two or more UPS in cascade, special care must be taken with the issue of harmonics and DHT (total harmonic distortion), the advice of a specialized electrical engineer becomes indispensable, trying to specify the detail required.
2. Power (Rating)
It must be calculated, adding the powers of all the equipment within the control room, the interconnection rooms and obviously all the electronic devices distributed in the project.
In the technical specifications of each equipment, the consumption expressed in Watts (W) or Volti-Amps (VA) is found. You must pass everything to the same unit (1VA = 0.707W or 1W = 1.414VA) and add.
A team expansion of at least 30% of the maximum considered at that time must be taken into account. Remember that if security systems are installed properly, the end user will continue to buy more equipment to cover more area and internal activities.
Finally, 25% tolerance and efficiency must be added. A UPS model that is above the calculated final value must be chosen. This depends on the brands available in each nation.
3. Autonomy
It is the time that the UPS must generate alternating energy at its full load, using exclusively its own batteries while there is no electric power service in the area.
It depends on many factors, among the main ones we can mention if there is a backup electricity generation system (gasoline or gas power plant), if there is an automatic transfer system that turns it on, if in the area there is good public service of electric type.
The more power outages routinely exist in the area, the more autonomy is required in the UPS. However, in many cases the UPS is calculated with a short autonomy (5 to 15 minutes), due to the security of a means of automatic generation of backup.
In case of needing greater autonomy You should not increase the power of the UPS, it is only recommended to increase the capacity of the battery bank, according to the tables of each manufacturer.
4. Scalability and modularity
We already know that a 30% expansion must be taken into account as a reserve in the power of the UPS, but due to the way security systems grow today, it is highly recommended that a brand be acquired that allows modularity in the devices and be able to modify their capacity through modules that alter both the power (W) and the autonomy (min.) of the electrical power system.
In this sense and depending on the capabilities in various brands, there are modules to be located inside racks or external in independent units. Compatibility between the various modules, batteries and control electronics must be total.
Depending on the physical size, it is possible that a different space is required than the equipment, dedicated exclusively to the electrical part, especially when they are independent units. In this case an air conditioning system (HVAC) may be required with different conditions than the equipment or operators.
5. Technology
There are several UPS technologies, unfortunately we do not have the space to detail and understand the benefits and limitations of each. We will only treat the two most common:
A) Standby, which waits for the electric service to be suspended to start taking DC power from its batteries, converting it into AC and delivering it in a regulated manner. This is the most common of all existing technologies. Its output wave is not an exact sine wave, but rather square, therefore it is composed of many harmonics that can affect the performance of the load. For a few milliseconds the load is de-energized.
B) On Line of Double Conversion. They are suitable for Electronic Security, especially for video systems. Regardless of whether there is public power or not, this technology always generates an electrical signal from your batteries. Due to its internal electronics, it produces an almost perfect sinusoidal signal, fully regulated and with transfer times equal to zero. They are really a total filter that prevents transients, peaks and over voltages from passing from the street to the load. Its only limitation is price.
6. Maintenance
Maintenance-free batteries (VRLA/VLA) should be used and with an efficient charge management policy, which prevents drip damage or decreases their life time by charging storage memory. The service life of a good quality UPS is greater than 15 years; but this is only achieved by using brands with adequate technical support and an efficient maintenance service (preventive, predictive and corrective).
7. Monitoring
UPSs for electronic security systems must allow monitoring all their basic parameters, to facilitate maintenance, anticipate possible failures, prevent quality errors in the power supplied or at least, take the necessary safety measures in time, in case the power outage is imminent. Nowadays it is essential that the UPS (even small) has a communications module and that using an open and known protocol (SNMP, XML, ModBus, among others), it can provide us with the necessary data to make a true monitoring and remote control, of parameters when necessary.
The presence of communications and monitoring software allows you to automate notifications through SMS, email, to anticipate possible failures and be able to integrate into a BMS/ BAS system.
They begin to use in the control center, software packages that make an automatic shutdown of loads (equipment), in case of power outages and low battery level.
8. Redundancy
When electronic safety systems are considered mission critical ,in many cases they are considered so), there must be redundancy in the UPS, it must have elements that can be changed without deenergizing (hot swappable) and to give greater stability cross power distributors (PDUs) must be used in redundant configurations that take electrical power from two different circuits. This is true both for the cabinets in the main control center and in the interconnection rooms. Topologies can be zonal, parallel, and serial (cascade).
Remember that a good measure of redundancy in the electricity generation system is given by the presence of an electric generator that is powered by natural fuels with a power of 1.5 to 3 times the power of the UPS.
9. Accessories and installation
A manual bypass board must be installed next to the UPS that allows in case of failure of the same UPS, to keep the power circuits of the entire safety system fed.
The UPS must be fed directly from the main distribution board and at the outlet must feed a regulated board that has the breakers and other protections, to energize the electronic safety equipment. The UPS exit board must be within the area protected by an access control system.
In the market there are three-phase, biphasic and single-phase models. Regardless of which one is acquired, we must remember that to avoid ground failures and maintain synchronism in all safety systems, we must always power all electrical devices of the same electrical phase, already supported by the UPS.
10. System topology
In small systems, it is customary to centralize all the capacity of the UPS in a single unit, but in large systems it is normal for smaller capacity UPSs to be distributed, which feed from the interconnection rooms some areas of devices and equipment. The benefits of the distributed option are lower costs and avoiding a single point of failure.
By space limits, we cannot describe more data. I hope you will continue to research and learn more details that will allow you to have an excellent electrical power system for your security systems.
* Germán Alexis Cortés H. is a Colombian Electronic Engineer, with a postgraduate degree in Engineering Management Systems. Consultant of the National Institute of Standards and Technology – NIST, in Electronic Security and Building Automation. CCP of ASIS, and CISSP of ISC2. He has over 20 years of experience in the electronic security industry. Renowned lecturer and university professor on high-tech issues at the Latino level. He has been a director of several companies in the sector and is currently a partner and directs Insetrón Ltda, an engineering and technical consulting company in electronic network projects for security, communications and automation. He has successfully participated in more than 150 projects at the Latino level. Contact him in the email [email protected]
