【Daily Question 20090223】DC Signals and AC Signals
Thread Content
In the production process, instruments often use DC signals for transmission. Do you know what advantages DC signals have over AC signals? Summary: 1. During the signal transmission process of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ； This post was last edited by baodingzhai on 2009-2-24 08:58]
1. During the signal transmission process of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator.
The input/output signals of industrial automation instruments are mostly DC signals, which have the following advantages: 1. During the signal transmission process in the instrument, DC signals are not affected by alternating current induction, making it easier to address the issue of interference resistance in such instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ；
The issue of interference resistance in instruments can be easily addressed during signal transmission, and the corresponding hardware must also be consistent; that is to say, items such as handheld controllers, safety gates, I/O cards, surge protectors, and isolators
1. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying the wiring. 2. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 3. DC signals are not affected by AC induction, making it easier to address the issue of interference resistance in instruments. 4. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc.
The input/output signals of industrial automation instruments are mostly DC signals, which have the following advantages: 1. During the signal transmission process in the instrument, DC signals are not affected by alternating current induction, making it easier to address the issue of interference resistance in such instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ；
The input/output signals of industrial automation instruments are mostly DC signals, which have the following advantages: 1. During the signal transmission process in the instrument, DC signals are not affected by alternating current induction, making it easier to address the issue of interference resistance in such instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ； That’s the standard answer, I guess
During the signal transmission of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments. For example, the pressure being measured is converted into a force through sensing elements such as spring plates, bellows, and diaphragms. This force causes the main lever to shift, which in turn causes the secondary lever to deflect; simultaneously, this induces a displacement in the detection element. Such displacement is amplified by a transistor-based detector, resulting in a DC electrical signal ranging from 0 to 10 mA. This current passes through the moving coil in a permanent magnetic field; the motion generated thereby produces a feedback force that balances the acting force. Once balanced, the detector no longer moves, and at this point the current output by the amplifier is the output current of the transmitter, which is proportional to the input pressure.
The input/output signals of industrial automation instruments are mostly DC signals, which have the following advantages: 1. During the signal transmission process in the instrument, DC signals are not affected by alternating current induction, making it easier to address the issue of interference resistance in such instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ；
Voltage and current signals with constant direction are called DC signals； Voltage and current signals that change direction and exhibit periodic variation are called alternating current signals. In a diagram of a sawtooth wave generator circuit, the capacitor’s actual function is to convert a square wave into a sawtooth wave; this merely reflects its property of blocking direct current while allowing alternating current to pass through, and it is not a rectification function. Rectification converts the “negative parts” in an alternating current signal into “positive parts”; it does not have a function of blocking or allowing passage. The \"block DC and pass AC\" property of a capacitor means that it presents significant resistance to the passage of DC signals, preventing them from passing through (i.e., \"isolating\" them), while it offers less resistance to AC signals, allowing them to pass through more easily. In a sawtooth wave generation circuit, the voltage‑filtering effect of the capacitor is manifested in the increase in the voltage across the capacitor, which is what is known as \"charging\". When analyzing analog and digital circuits, the direction of signals is primarily based on the voltage direction, as the voltage values in these circuits are generally higher than the current values. This is especially true for low-power circuits, where the voltage is high while the current is relatively low. Moreover, the current in these circuits is generated due to the presence of voltage; that is, voltage comes first, and current follows.
1. DC signals are not affected by AC induction, making it easier to address the issue of interference resistance in instruments. 2. DC signals do not have the issue of phase shift. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance
1. During the signal transmission process of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ； The above content is basically the standard statement.
The input/output signals of industrial automation instruments are mostly DC signals, which have the following advantages: 1. During the signal transmission process in the instrument, DC signals are not affected by alternating current induction, making it easier to address the issue of interference resistance in such instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ；
1. During the signal transmission process of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments； 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift; therefore, the wiring is simple ； 3. DC signals are suitable for analog-to-digital and digital-to-analog conversion, thereby enabling instruments to be easily connected to data processing devices, computers, etc ； 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance.
1. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying the wiring. 2. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 3. DC signals are not affected by AC induction, making it easier to address the issue of interference resistance in instruments. 4. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc.
1. During the signal transmission process of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ；
1. During the signal transmission process of instruments, DC signals are not affected by AC induction, which makes it easier to address the issue of interference resistance in instruments. 2. DC signals are not affected by the inductance and capacitance of the transmission lines, and there is no issue with phase shift, thus simplifying wiring. 3. DC signals are easy to convert between analog and digital forms, which enables instruments to be easily connected to data processing devices, computers, etc. 4. It is easy to obtain a reference voltage for DC signals, such as the setpoint of a regulator. 5. A standard 4-20mA DC current signal can also reduce losses caused by wire resistance ；