How to choose power supply for door access control system?
In order to meet the needs of the access control market, door access control systems suppliers and manufacturers, including supporting optical transceivers power supplies, etc., are optimizing their access control product solutions according to the specific needs of the door access control system market. To make their own can be more competitive in the market.
This article is mainly for the characteristics of access control system applications, combined with their own actual access control system project engineering experience, to share in the actual project selection, how to choose and judge the door access control power supply.
The importance of access control power supply
There is no doubt that the access control power supply is the basis for ensuring the stable operation of the entire door access control systems. The choice of the power supply can directly determine whether the access control system integrator or installer can earn as much profit as possible when implementing the project, and at the same time, t can also reflect the ability of the engineering firm to control the quality of the access control project from the power supply choosing.
Unfortunately, when investigating the macro market of the entire access control, it was found that more than 90 system failures were caused by improper selection of power supplies, and some failures may have affected the smooth promotion of the project. In summary, the faults caused by the power supply are mainly manifested in the following aspects:
- After using for a while, there is a problem of insufficient power supply.
- After a thunderstorm, a large-scale power failure occurred.
- There is a power failure in hot and cold weather.
- The battery is often broken and does not have the ability to power down to maintain normal operation of the system.
- The short circuit caused the power to be burnt out.
- During the peak period of power consumption, there is a problem of insufficient power supply.
How to choose a power supply for door access control system?
1, Measure the actual output power of the power supply
The door access control system involves a lot of equipment to be powered. To ensure that all access control devices can operate normally and stable, the power supply needs to have enough power to supply power to each device. When purchasing the access control power supply, paying special attention to the nominal value of the power supply, and it is best to test the actual parameters in the field, because there are some low-cost access control power supplies on the market that often fail to reach the nominal value in practical applications, which seriously affects the access control. The system operates normally and stable.
It is recommended to select the access control power supply manufacturer with the standard technical parameters, reliable quality, good reputation and suitable for the gate access control system. At present, some access control system manufacturers, the power supply is sold together with the access controller. Generally, such manufacturers consider the actual application of the project for the power supply selection and have better protection for the overall quality of the system.
An easy way to test the output power of the power supply: add the load corresponding to the power output of the power supply (such as cement resistance), run for more than 48 hours, measure the actual output voltage and current of the power supply with a multimeter, and compare it with the nominal value to Is the voltage output after the load is detected stably? Is the calorie normal? It is best to be able to install the test run in the field.
2, Effective lightning protection
Due to the particularity of the access control system project, the bad access control system installation environment (farmers’ houses, rented houses), the outdoor lines are intertwined, and it is easy to attract lightning, the lines connected by the power supply are inevitably appearing outdoors. Therefore, the power supply is required to have strong and effective protection measures against lightning protection.
Whether the product has lightning protection judgment:
- Visually check if there is a protection circuit design on the power supply. (This method is suitable for researchers on circuit hardware).
- Understand whether the manufacturer has accumulated technology in lightning protection technology, such as the actual demonstration of product reliability. Lightning detection reports for related products, etc.
3, Wide temperature adaptation range
If the access control system power supply device does not have a wide range of adaptation to high and low temperatures, the reliability of the whole access control system is not guaranteed, especially the power supply part, so the product should be selected according to the access control system installation environment.
In general, the temperature adaptation range is -40 degrees – 85 degrees.
4, Intelligent charge and discharge management of backup battery
In some special environment, to keep the whole door access control system running normally and correctly at any time, the specifications for building access control systems are everywhere. For the battery life of the backup battery will be specific requirements, generally, require that the system can maintain normal operation for 4-6 hours after power off, the power supply has charge and discharges management functions.
The charging and discharging management function of the power supply mainly prevents the battery from being overcharged and damages the battery, and does not recharge after over-discharging. The charging current is too large to lower the current supply of other devices, resulting in unstable system.
5, fault isolation, to avoid damage to individual equipment and affect the overall stability of the system
Due to the diversity of hardware devices in the access control system, it is bound to involve a power supply to provide a unified power supply to multiple devices. It is necessary to pay attention to the optional power supply with multiple output terminals for independent power supply output, and the power supply can intelligently judge the output current. This can solve the power supply centralized power supply or when the output of one power supply fails, it will not affect the power supply output of other circuits. Even if the output of one power supply is directly short-circuited, it will not affect the output of other ports. Of course, the power supply will not be burnt out due to a short circuit on one port.
6. Wide voltage adaptation range, stable power supply output
Mains voltage fluctuations often occur, either high or low. Therefore, the power supply must have a wide range of mains voltage fluctuations, and the output voltage can be stabilized at a 12V output, avoiding unstable power supply caused by fluctuations in the mains voltage, and affecting the normal and stable operation of the access control system.
7, On the choice of switching power supply or linear power supply
In the actual access control system application, whether to choose switching power supply or linear power supply?
Advantage: stable performance without the interference of high-frequency ripple.
Disadvantage: heating, low use ratio of power without any superpower to select.
Switching power supply
Advantage: high power supply is easy to supply the power for it. And it shows a better cost-performance ratio. Small size, lightweight and many options for brands and models.
Disadvantage: low-quality power supply and uncontrollable high-frequency ripple will cause the access controller crashed and the door is unable to be opened which has a poor anti-interference.
But many access control system engineers have no way to start, in fact, just grasp two points:
- In a hot area, if a linear power supply is selected, it is not recommended to place the linear power supply and other types of equipment in the same equipment box, because the consumer of a linear power supply is high, and if other types of equipment are in one equipment box. If the heat is not delivered in time, it is likely to cause unstable operation of other access control devices. And if the linear power supply is equipped with a dedicated cabinet, it will bring some cost increase.
- Low-cost linear power supply generally does not have battery charge and discharge management function, which can easily cause battery damage.
8, Finally, 5 Tips to choose a suitable access control power supply
12V DC is used on most access system, which means the power could be evaluated by a parameter of current. On consideration of its impact resistance and steady operation, suggestions are made as follows:
Tip A, If a linear power supply is preferred, a controller with 4 NONC, a nominal 5-7A linear power supply is suggested.
Tip B, If a linear power supply is preferred, a controller with 1 NONC, over nominal 3A linear power supply is suggested.
Tip C, If switching power supply is preferred, a controller with 4 NONC, a nominal 4-5A linear power supply is suggested.
Tip D, If switching power supply is preferred, a controller with 1 NONC, over nominal 3A linear power supply is suggested.
Tip E, If there are 8 NONCs or 6 mag locks with a controller, over nominal 10A switching power supply is suggested.