In the past, it was standard practice for customers to request the use of a transformer to provide isolation for the control circuit from the rest of the equipment. Typically, a transformer would be used to convert 480V to 120V, followed by a power supply to convert 120VAC to 24VDC for circuits. However, the trend now is to use 480VAC to 24VDC power supplies more frequently. Do transformers still offer an added layer of isolation that power supplies do not? Are there any other advantages to using a transformer before stepping down to 24VDC? Is there a technological advancement in power supply construction that has made transformers unnecessary when 120VAC is not required? When I first entered the industry, 24VDC circuits were just gaining popularity. It was common to see HMIs and PLCs powered by 120VAC, even if IO cards operated on 24VDC.
While working on machines with 480/24 VDC power supplies, I've noticed a recurring need for a 120Vac power source. To address this need, I now rely on a transformer with a 480/120 voltage conversion capability for any potential future requirements that may arise.
Many contemporary 24V DC power supplies now offer full isolation, depending on how the DC- terminal is utilized. They also come equipped with multiple protective and over-boost features, marking a significant advancement from traditional setups involving transformers, rectifiers, and large capacitors.
Nowadays, a majority of power supply units (PSUs) use switchmode technology with a transformer for isolation. The mains supply is rectified, chopped at a high frequency, and then sent to the transformer, which is typically smaller due to the higher frequency of the switched supply. This results in fewer turns being required. In essence, most PSUs with voltage outputs ranging from 415-120v to 24V DC are isolated. Additionally, these PSUs provide superior crowbar protection against peaks and overloads.
It's important to have the control circuit supplies properly grounded to prevent voltage differences that could lead to dangerous situations. Make sure that one of the output terminals of the power supply or transformer is connected to 0V, either through the installation's neutral or a neutral line created and connected to ground. Isolating control circuits can result in significant voltage variations that pose risks of up to thousands of volts.
A common question posed by controlsgirl is whether a transformer offers an additional layer of isolation that power supplies do not. The answer is yes - transformers do provide an added layer of isolation, although it should not be confused with added protection. It is possible to achieve multiple layers of isolation by feeding a 24V supply through a series of transformers. However, it is important to note that having multiple transformers in the system may not necessarily offer any extra benefits. Another query from controlsgirl is inquiring about the advantages of using a transformer before stepping down to 24VDC. One benefit is the ability to install an outlet for devices like laptops. However, caution should be exercised as the outlet may become unusable if overloaded with high-powered tools or appliances. Lastly, controlsgirl wonders if advancements in power supply technology have made transformers obsolete when 120VAC is not required. The answer is yes - switch mode power supplies are more energy efficient and cost-effective than traditional transformers. Additionally, these modern power supplies can be equipped with intelligent protection features to prevent downtime caused by power interruptions.
Transformers indeed offer an added layer of isolation as they can break the electrical connection between the source and load, enabling safer interaction with sensitive equipment. That said, advancements in power supply technology have significantly improved the efficiency, compactness, adaptability, and safety, making the direct step-down to 24VDC from 480VAC feasible. Moreover, using a transformer to first step down to 120VAC adds extra cost and complexity to the panel. You can get power supplies with reinforced isolation to increase the safety of your control circuit from the rest of your equipment. However, the choice between the two really depends on the additional protection needed, existing set up in your factory, and the budget. The growing trend towards 24VDC is likely due to these developments and the overall demand to reduce costs and simplify the designs where practically possible.
Transformers indeed offer an isolation aspect that straightforward power supplies typically don't. However, the surge in popularity of transformer-less power supplies comes with their own set of advantages. For one, they're cost-effective, space-saving, and generally more efficient in terms of energy consumption. More importantly, power supplies have significantly improved in reliability and safety features. The development of Power Supply Units (PSUs) that directly convert 480VAC to 24VDC, for instance, now incorporate protective measures such as short-circuit, overload, over-voltage and over-temperature protections, effectively sidelining the need for a transformer in most circumstances. Yet, in highly sensitive applications like certain medical equipment, the additional isolation provided by a transformer could still be a crucial factor.
Certainly, your point about isolation is still valid in some areas - transformers can offer an additional layer of protection for sensitive electronics by disconnecting the control circuit from the power supply, reducing risk from surges or faults. However, the current trend towards 480VAC to 24VDC power supplies is driven mainly by efficiency and space-saving - these units convert power in one step without the need for a transformer, and typically have a smaller footprint. It's also worth noting that modern power supplies have significantly improved in terms of their built-in protections against spikes or overloads, so in many cases, the extra isolation provided by a transformer is no longer as crucial as it used to be. But, this comes down to the specific requirements of your setup - if you're working with extremely sensitive equipment, or in environments with unstable power, using a transformer might still be the best option.
It's interesting to see how the industry has evolved! While modern 480VAC to 24VDC power supplies are more compact and efficient, transformers still provide that critical isolation which can protect sensitive control circuits from surges or spikes. This adds an extra layer of safety that’s hard to overlook, especially in environments with heavy machinery. Moreover, transformers can offer some level of voltage regulation and noise filtering, which can be advantageous for particular applications. That said, advancements in power supply technology, like improved switch-mode designs, are indeed making it feasible for some setups to bypass traditional transformers, particularly when you're confident in the quality of your incoming power. Ultimately, the choice really depends on the specific application and the level of risk tolerance for electrical disturbances.
Great points! While modern 480VAC to 24VDC power supplies are definitely more efficient and compact, transformers do provide that additional isolation which can be critical for protecting sensitive devices from surges or other electrical noise in the system. Moreover, transformers can help mitigate issues related to ground loops and electromagnetic interference, which can be especially important in complex control systems. However, with advancements in power supply technology, such as better filtration and built-in safety features, many applications now find that transformers are often unnecessary, especially where space and efficiency are priorities. It's fascinating to see how quickly the industry evolves, though—I remember when every control system seemed to require an extensive transformer setup!
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Answer: - Yes, isolation transformers offer a dedicated layer of isolation that power supplies may not inherently provide, helping protect control circuits from electrical interference and ground loop issues.
Answer: - Transformers can help provide galvanic isolation, reduce noise interference, ensure safety by isolating circuits from higher voltages, and offer better protection for sensitive components.
Answer: - While advancements in power supply technology have made direct conversion from 480VAC to 24VDC more feasible, transformers are still preferred for certain applications where isolation, noise reduction, and circuit protection are critical.
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