Why 24 Volts DC Power Supply is Used?

This article describes reasons for the use of 24 volts DC power supply in electronics, instrumentation, and automation. As we know, all major industrial automation and control systems use a 24V DC power supply. Most of the sensors, instruments, and control devices use the 24V DC power supply. Today in this article we will discuss 24V DC supply’s advantages, disadvantages, and reasons for the use of DC supply.

Advantages of 24 VDC Power Supply

Why 24 Volts DC Power Supply is Used?

The followings are the advantages of a 24 VDC power supply.

  • The first and main advantage of a 24V DC supply is less arc generation. AC supply of 120V or 230V could be risky considering that it will produce a good amount of electric sparks and arc. This can be dangerous for the surrounding personnel and/or the environment.
  • The second advantage is the risk factor is very less in the 24V DC power supply because it produces less and sometimes negligible amounts of electric arc and electric spark. Due to such low voltages, there are hardly any chances of a person getting an electric shock when touching it.
  • The third advantage is that the current carrying capacity of the DC supply is limited. But this does not mean that it will not be able to drive an instrument. The current is enough to power the device.
  • The fourth advantage is that the 24 Volts DC supply does not need a fuse. Whereas, the AC supply always requires a fuse. When a short circuit takes place, it simply cuts off the supply to the instrument because of its limitation. It seems like fuses are not needed for DC supply. But it is used in many applications based on the requirement of the user to provide additional protection to the device.
  • Because of the normal behavior of the DC supply, it is possible to reduce the size of the instrument or power supply. This will reduce the cost and complexity of the system. On the other hand, bulky and oversized instruments for AC supply are not easy to handle and require a lot of space.
  • The heat dissipation of AC devices is more. These days, semiconductors function at nano-sized levels, and reduced DC supply size makes it helpful in increasing reliability, decreasing cost, and increasing the efficiency of the instrument.
  • The output of DC voltage is more constant and less prone to fluctuations as compared to AC voltage. Hence the instruments get a fixed voltage at a much higher percentage rate. When the fluctuations are less, the performance is also higher. The higher rate of fluctuations or short spikes in voltage at the upper level may damage the circuitry. Therefore, 24 Volts DC power supply is good for instruments.
  • The instruments having a 24V DC supply can drive 500-600 ohms of load resistance. This is enough for a valve positioned also which is heavy in operation. Hence, the load-carrying capacity of the DC supply is also good as compared to the AC supply.
  • The DC supply has more noise redundancy as compared to the AC supply.
  • Electricity can be stored in DC power. So, UPS or batteries use a DC power supply.
  • DC power can help in reducing the risk of electrical fires or other hazards.
  • DC power systems are safe and efficient.
  • By using DC power, the overall efficiency of the plant can be improved by reducing the amount of energy lost in the form of heat during transmission.


  • The major disadvantage of DC supply is that it cannot be used for longer distances. It faces a reduction in signal capacity over long distances.
  • The 24V DC supply cannot be used for driving high current loads.

Looking at the numerous advantages of the use of 24 volts DC power supply, it is preferred for electronics and instrumentation devices.

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