Excessive voltage drop at the safety barrier output
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I had been using a combination of a transmitter and a safety barrier until recently, but I encountered a transmitter for which the voltage dropped to around 6V after it was connected to the safety barrier (the input voltage was 24V), which prevented the transmitter from functioning properly. Many people I asked said it was due to the high power consumption of the transmitter; I was wondering if anyone knows the reason So how should it be solved?
First, determine whether this voltage transformer is intrinsically safe, flameproof, or non-flameproof
First, determine whether this voltage transformer is intrinsically safe, flameproof, or non-flameproof
1、There is a voltage drop across the safety barrier, of about 5V. . . Let me say this: the safety barrier is a useless piece of junk; it’s by no means a reliable way to stabilize the power supply – it’s not dependable at all when in use. 2. Use a safety barrier, and perform some calculations on the resistance in the current circuit. The transmitter can output properly across its full range only if the following formula is satisfied. ❲ Supply voltage – safety barrier voltage drop = 0.02×(wire resistance + current sensing resistor) ❳ ≥ Minimum excitation voltage allowed by the transmitter. 3. Be concise and to the point. Reptiles can’t understand it; it has nothing to do with me. Reptiles, little reptiles – they can crawl however they want. The following ten thousand words are omitted .............................. :lol
1 Try replacing the safety barrier. 2 Try replacing the transmitter
There is indeed a voltage drop, and the reason why this voltage drop reaches an astonishing 18V is... We are now planning to modify the transmitter in order to meet the requirements of the safety barrier, as this is a systemic issue – it’s not as simple as just replacing the safety barrier! ! Thank you, what you said makes a lot of sense
The last edit to this post was made by 1111111 on 2019-7-6 at 12:47. The 18V drop is not entirely due to the drop across the safety barrier; it is likely that most of it occurs across the resistances in the circuit. . . Due to the relatively high resistance in the circuit, for example, if the sampling resistors used in the DCS cards are not low values such as 100 or 50Ω, but rather high values of 500Ω, then when current flows through these resistors, a significant voltage drop occurs across them. This results in a lower voltage reaching the transmitter terminals. When this voltage is too low and falls below the minimum allowable excitation voltage for the transmitter, it cannot output the theoretical current; instead, it outputs a lower current in accordance with Ohm’s law. :Lol, moreover, when powered by 24VDC, the effective output of the safety barrier is around 18V. This means that only a few volts of voltage are available for the loop resistance. You need to check what the minimum excitation voltage allowed by the transmitter being used is. . . It generally should not be higher than 13V DC. . . Otherwise, the circuit design of the meter is the kind that’s annoying. :Lol. Additionally, it is also possible to consider raising the drive voltage to 28V DC for power supply. . . It is generally not advisable to exceed 30V, as doing so increases the risk of damaging the chip and the circuit. .
Thank you! I learn from it. During actual testing, continuous pressure was applied to the transmitter; as the pressure increased, the voltage kept dropping significantly and showed strong attenuation. It fails to meet the usage requirements entirely