Remote Communication Control—On the Rise, Future Promising
With the rapid development of electronic and software technologies, it is becoming increasingly common for electrical control systems involving long-distance control and monitoring to accomplish tasks using various communication protocols and corresponding equipment. For example, terms frequently mentioned by some industry colleagues, such as **Ethernet**, **RS-485**, and **RS-232**, all fall within the scope of this control method. Naturally, remote communication control technology based on wireless communication is also steadily developing and is bound to lead another new revolution in electrical control systems in the future.
Frequency Inverter (VFD)—King of the Electrical Control Arena
Due to the influence of technology and price factors of domestic Variable Frequency Drives (VFDs) over the past ten or so years, traditional step-down starting electrical control circuits, such as **Y/Δ (Star-Delta)**, **frequency-sensitive rheostats**, and **autotransformers**, have almost completely disappeared from actual electrical control systems! They have been replaced by VFDs of various brands—VFDs can easily handle the load starting process and satisfy the need for speed regulation, making them hard to resist! While replacing traditional step-down starting circuits, even the once-popular **Soft Starter** has been marginalized by VFDs—after all, most users are not experts, and coupled with the hype that "using a VFD definitely saves electricity," it's hard for soft starters to hold their ground!
Clustered Electrical Control Auxiliary Circuits—Bundled Wiring Becomes the Norm
The widespread adoption of control equipment like **PLCs (Programmable Logic Controllers)**, **HMIs (Human-Machine Interfaces/Touchscreens)**, and **VFDs** has led to the control auxiliary circuits (or secondary circuits) using increasingly thin and numerous wires. Consequently, to make the auxiliary control circuits neat and aesthetically pleasing, the auxiliary circuit wires are now often bundled together (clustered). Furthermore, the emergence of various types of **aviation plugs (circular connectors)** with flexible and diverse wiring methods, as well as **single and dual-row DIP (Dual In-line Package)** wiring components, has made the bundling of auxiliary circuit wires an inevitable trend.
Solid-State Relays (SSR)—Gradually Coming to the Fore
Due to the massive use of **PLC** devices, the **Solid-State Relay (SSR)**—an electronic semiconductor device for low-voltage, micro-current control that is contact-less, spark-less, and capable of high-frequency operation—has finally entered the fast lane of widespread use after more than twenty years of continuous development and refinement! In some of the large and medium-sized electrical control systems the author has encountered, the phenomenon of PLCs driving single/three-phase SSRs is becoming increasingly common—this is highly related to the SSR's ability for high-speed action response!
PLC—Completing the Upset and Rising Prominently
A few days ago, when the author was repairing an electrical control system for a boss, I was surprised to find that even circuits as basic as **forward/reverse rotation** and **timed starting** were being completed in their control system using a certain high-imitation Mitsubishi PLC—it was supposedly cheaper and simpler this way. Through this example, it is not difficult for everyone to see how high the current penetration rate of PLCs is! Aside from the price advantage of domestic independent PLC brands, the author feels that the increasing use of PLCs can be attributed to two main factors: firstly, the growing demand for **automated production**; and secondly, the increasingly high **PLC technical proficiency** of most practitioners—I believe no colleague wants to do extra wiring!