Are there many two-wire electromagnetic flowmeters?
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Are there many two-wire electromagnetic flowmeters? Do I still need external power supply when entering DCS?
There are two-wire and three-wire electromagnetic flowmeters, and signal transmission includes 4-20MA and RS485. You can check online for details.
There are not many two-wire systems, but there are many four-wire systems.
There are many electromagnetic four-wire systems. If it is used in the control system, it needs a separate power supply, that is, two-core signals and two-core power supply.
There are very few two-wire ones, because it needs to provide the excitation power of the coil, and it is difficult to achieve a power consumption of less than 4MA. Most of them are four-wire, two power wires (can be 24V or 220VAC), and the other two signal wires. If it is a separate type, there is a special cable connection between the sensor and the transmitter. reminder: Electromagnetic flowmeters have strict grounding requirements. This post was last edited by hxmhn on 2009-2-21 16:15 ]
Yokogawa Electric launches the ADMAG AXR two-wire electromagnetic flowmeter with dual-frequency excitation. It is the world's first two-wire electromagnetic flowmeter using dual-frequency excitation. The product went on sale in February 2009. When two-wire instruments enter the DCS system, DCS needs to provide DC24V loop working voltage.
Those powered by lithium batteries can be two-wire systems, and basically use four-wire systems.
There are many electromagnetic four-wire systems. If the signal line enters the DCS, it needs a separate power supply. The signal line needs to add a safety barrier when entering the DCS.
There are many electromagnetic four-wire systems. If the signal line enters the DCS, it needs a separate power supply. The signal line needs to add a safety barrier when entering the DCS.
Because electromagnetic flowmeters require excitation voltage and consume relatively high power, most of them are 4-wire systems. In recent years, with the development of science and technology, some manufacturers have been able to make some small-diameter flowmeters into two-wire systems. However, large-diameter and high-power flowmeters are still four-wire systems.
E+H's 23 series electromagnetic flowmeters are all 2-wire, with diameters ranging from DN25-DN200.
What you said above is good, this is what we use.
Most electromagnetic flowmeters adopt a four-wire system, with separate power supply and signal transmission. There are also a relatively small number of manufacturers that produce two-line systems.
We use a four-wire system, but now we have an accurate one. We are looking into the cause.
Most of the electromagnetic flowmeters I have seen are three-wire or four-wire. In fact, the third and fourth lines are basically the same. Because the power supply needs to supply power to the excitation coil of the electromagnetic sensor, the general two-wire system cannot meet its load.
We use two-wire systems here, and we also have four-wire systems.
Generally, a four-wire system is used, and external power distribution is required to enter the DCS.
Is the grounding bad? You can try grounding the neutral wire.
There are not many two-wire systems. Electromagnetic flowmeters require excitation. Two-wire ones are more difficult to make, but they are indeed available on the market. I have seen E+H ones, the ones mentioned above.
There are very few two-wire ones, because it needs to provide the excitation power of the coil, and it is difficult to achieve a power consumption of less than 4MA. Most of them are four-wire, two power wires (can be 24V or 220VAC), and the other two signal wires. If it is a separate type, there is a special cable connection between the sensor and the transmitter. reminder: Electromagnetic flowmeters have strict grounding requirements. The four-wire system can also be artificially converted into a three-wire system. Then there will be one wire that can be shared. Generally, there are very few in the two-wire system.