At the heart of any electrical supplyA modern measuring system is a 24V power supply. Without the participation of this element it is impossible to imagine the work of any current loop. The principle of its operation is the following: all electronic devices are assembled sequentially into one large ring, through which current is circulated (most often it is 4-20 mA). The 24V power supply is a voltage source. The magnitude of the current changes the sensor depending on the parameter. And as the receiver serves the analog input
Circuit Implementation
The structure of any such device includes the following modules:
Вставка плавкая – это предохранитель, который protects the device from overload. Once a high current value is applied to the input, it burns out, resulting in the entire system being de-energized. At the same time, all its components remain functional. The transformer consists of two windings. The first of them is the primary one (220V is supplied to it), and the second one is secondary, on which 24V is obtained. That is, it just just lowers the tension. The diode bridge from the alternating signal makes a constant. The filter stabilizes all output parameters by smoothing various pulsations. The last component - the control unit - can be found only in modern devices such as a 24V power supply. It measures
Specifications
The first two parameters are interrelated.For example, if the maximum current of 22 mA is allowed at the output, then the power of the block will be 5.28 W (multiply by 22 mA by 24 V, current by voltage). To minimize the space occupied by such devices in measuring cabinets, multichannel sources are used. This is justified in cases where there are many measuring parameters in the system. The degree of protection of the case is denoted by the letters "IP" and a digital index. The bigger it is, the more secure everything inside is protected. It is necessary to pay attention to this value in cases when operation is to be carried out in a hostile environment (for example, in the chemical or metallurgical industry). According to the type of mounting such devices are of two types: screw and DIN-rail. The first of these are outdated modifications, which are gradually disappearing from use. The latter are installed on a special rail, and this has now become the de facto standard. The last parameter that characterizes the power supply
How to choose?
The algorithm for the selection of such devices is as follows.Determine the number of consumers and their total capacity. Suppose it is supposed to work with a powerful solenoid valve per 100W and with a current at peak load of 5A. It is recommended to take power margin of about 20%. To do this, we multiply 100W by 1.2, we get 120W - power, indicating that our 24V 5A power supply unit (120W / 24V) will have just such indicators. It is from devices with such characteristics and you need to choose. Further, it is necessary to consider the operating conditions and temperature conditions, if necessary.
Let's sum up the results
24V power supplies are very important components.modern automated process control systems. Without them, it is impossible to imagine the full operation of any measuring system today. Their choice must be approached very thoroughly. In the event of a breakdown of such a component, failure of other parts of the system is possible.
