Built-in Power Supplies; Output current:50A

Built-in power supplies are just one of many power supply categories present on the market. As the name suggests, built-in power supplies are designed for further integration or incorporation into a larger system. They can be used to power all kinds of devices, machines, circuits created by hobbyists, such as 3D printers, as well as specialized robots, which are increasingly often implemented in many industries.

Choice of power supply solutions

When selecting a power supply, the most important thing is to know what it is supposed to be used for and to determine the parameters of the circuit it will power. The most important aspect is the output voltage, given in volts [V]. The majority of such devices, excluding those designed for special applications, have DC (Direct Current) at their output. This is because the vast majority of electrical and electronic equipment and devices are powered by this particular type of energy. Too high or too low output voltage can lead to damage to the powered components or to the power supply itself. Some of the power supplies can adjust the output voltage, so that it can be matched to the specific system. Output voltage adjustment in such power supplies can be done through an external control signal, often in the range of 1 to 5.5VDC or through a simple potentiometer. Of course, the supply voltage of the power supply itself is equally important, but most often it will be the AC (Alternating Current) with a voltage of 230V, coming from the electricity grid.

The current at the output of the power supply is another important parameter. The maximum current capacity, given in amperes [A], indicates the maximum electric current that a given power supply is able to generate while still working properly. This value should be greater than (or, in some extreme cases, equal to) the current required by the system that is being powered. A power supply operating within its maximum output will generate a significant amount of heat, which can damage its components under prolonged exposure, especially if there is no overload or overheat protection. It is recommended to choose a power supply with a higher current capacity than required, first of all so that it does not operate at the upper limit of its current capacity, but also so that, if the system is extended, it does not lead to a situation where it is necessary to replace the existing power supply with a new one with a higher current capacity.

The parameter that is closely related to the output voltage and the maximum amperage is the power, which is given in watts[W]. In the case of DC voltage, it is nothing else than the product of the voltage and the output amperage of a given power supply. For AC, remember to multiply the RMS values of these parameters by each other. Wattage is almost always given for easy comparison as to which power supply is more efficient.

Another aspect that is sometimes overlooked is the temperature range in which a given power supply can operate. Most built-in power supplies will most probably be placed in stable, friendly conditions, close to room temperature. However, some applications may require operation in sub-zero temperatures or in an environment where the temperature will be significantly higher. There are power supplies that can operate efficiently at -55°C or 85°C. If your power supply is likely to be subjected to these conditions, do not overlook this aspect when making a selection.

Built-in transformer power supplies

The main two types of DC power supplies are switching power supplies and transformer power supplies. This division is due to the differences in their construction and the way they process current. A transformer power supply, often called a linear power supply, is based, as the name implies, on a transformer, which, right at the input of the power supply, scales AC voltage, usually 230V AC, to the AC voltage of a lower value. Then, it is rectified by a bridge rectifier in order to obtain direct current, filtered and appropriately controlled by internal systems that provide a constant output voltage with the least possible interference. These types of power supplies have a low output ripple and noise and, especially the lower power supplies, are relatively inexpensive. Their biggest disadvantage is their large size and weight, as they are several times heavier than switched-mode power supplies and definitely larger, at the same unit power. They are also less efficient due to the heat loss associated with eddy currents in the transformer core.

Built-in switched-mode power supplies

In switched-mode power supplies, the input voltage is immediately rectified to obtain high-voltage direct current, which is then filtered and switched at a frequency of 10 to 100 kHz through power transistors to generate AC pulses. It is obligatory, because in the next step this voltage is applied and scaled via a relatively small transformer to a much lower AC voltage. Then, in order to smooth it as much as possible, before leaving the power supply, it is rectified again and filtered through an LC filter (inductor-capacitor). The proper course of these operations is ensured by an appropriate internal control system. The undoubted advantage of switching power supplies, compared to transformer power supplies, is a much lower weight and a smaller size. They also have a higher current efficiency for each of the possible output voltages, i.e. high power density, and they are cheaper when it comes to the manufacture of higher-power supplies. The disadvantage of these devices may be higher noise and ripple at the output, especially when it comes to high-frequency interference.

Built-in buffer power supplies

Buffer power supplies are special types of built-in power supplies. They have an additional input which is used to connect rechargeable batteries, often in the form of a classic lead-acid battery. It is capable of maintaining the operation of the powered device in the event of disturbances, fluctuations and drops in the supply voltage from the power grid. Power supplies of this type are most often used in various branches of industry and in factories in order to provide uninterrupted power supply to systems like access control, work time registration or electronic door locks, ensuring uninterrupted access to rooms in a building. There are models that are sold in specially designed housings for a battery with a specific capacity, so you do not have to worry how to fit them in the system.

Power supplies and emergency power systems

Another specialized type of power supplies are power supplies and emergency power systems. Like the buffer power supplies, they have an additional battery slot that serves as a backup power source. As a result of detecting a power failure from the grid, the power supply unit automatically switches to battery operation, transforming low-voltage direct current into high-voltage alternating current, and thus maintaining the power supply to the devices connected to it. When this type of power supplies is discussed, you can often come across the term Pure Sine Wave. It is often used when describing devices converting direct battery current to 230V alternating current, which is used to power most electrical and electronic devices. The devices whose documentation does not mention Pure Sine Wave most often generate 230V alternating current in the form of a trapezoidal signal, which in fact only mimics the sinusoidal waveform of the power grid, so some devices may or may not work incorrectly.

Built-in industrial power supplies

We can also distinguish industrial power supplies which resemble standard desktop computer power supplies in terms of their structure and terminals. They have outputs with DC voltages of -12V, -5V, 3.3V, 5V, 12V and ATX motherboard plugs, as well as MOLEX or AMP connectors. These are mainly used to power industrial computers that must meet specific requirements in terms of reliability, resistance to interference and other undesirable external factors.

There are different types of mounting for built-in power supplies, which can sometimes make a significant difference. Industrial applications will most often use power supplies that will be mounted on a DIN rail, while for domestic applications, (such as powering LED lighting) you can find power supplies in a housing designed for flush mounting. Buffer power supplies will most often be placed in a special housing, adapted for wall mounting, there are also transformer power supplies intended for screw mounting. In addition, there are panel-mounted devices as well as PCB-mounted devices available.

The majority of power supplies will incorporate various types of protection. Here, we can distinguish protection against overload, short circuit, overheating, overvoltage, and (in specialized power supplies) also protection against reverse polarity of the connected battery, its excessive discharge and overcharging.

Power supplies can have various electrical connections, such as terminal blocks or integrated cables, as well as additional functions and accessories. There are many ways to configure a dedicated power supply – everything depends mainly on the intended use, operating conditions, the other components in the system and devices to be powered, so you should consider a number of factors that will help you choose a power supply that meets as many predetermined guidelines as possible.