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How to ground the shielded cable is a common problem when people do electrical work. Many people ask us: Should a shielding cable ground both ends or one end? This answer is not very definite. Different situations need different analyses. This article will show some knowledge you should know about PVC shielded wire.
This article mainly includes three parts:
First of all, we should know what is a shield wire.
A shielded electrical wire structure includes not only a copper conductor, PVC insulation, and PVC outer sheath, different from other electric power cables, but also a shielding layer. This shielding layer makes it has an important shielding function. Shielded copper wire also includes double-shielded cable and single-shielded wire. Double shielding wire has two layers of shielding, single shielding wire has only one layer of shielding. The shielding layer can well protect the signal transmission from interference and safety. Below is a picture of shielded copper wire.
Next, we will introduce the shielding cable wire ground method.
Usually, there are three methods when grounding: single ground, double ends ground, and shield suspension.
Imagine the signal current i1 enters into the shielding wire from the conductor, after flowing through the load resistor RL, it will return to the signal source through the shielding layer. Since i1 and i2 are equal in size and opposite in direction, the magnetic interference they generate cancels each other out. This is a good measure to suppress magnetic field interference. At the same time, it is also a good measure to resist magnetic field coupling interference.
Since the current flowing on the shielding layer is the superposition of i2 and the ground ring current iG, it cannot completely cancel the magnetic field interference generated by the signal current. Therefore, its ability to suppress magnetic field coupling interference is also worse than that of single-ended grounding. Both the single-end grounding mode and the two-end grounding mode have the effect of shielding electric field coupling interference.
Only can shield electric field coupling interference, but not the ability to suppress magnetic field coupling interference.
Now, we will discuss should a shielded instrument wire ground both ends.
Whether a shield wire should ground one end or both ends, is not an absolute question. Under some circumstances, one end grounding is OK, but under other circumstances, both end grounding is OK. Here are some introductions about it.
At this point, the outer shield induces a current due to the potential difference, thereby generating a magnetic flux that reduces the strength of the source magnetic field, thereby essentially canceling the voltage induced without the outer shield. If it is to prevent electrostatic interference, it must be grounding at a single point, whether it is a layer or a second layer of shielding. Because the electrostatic discharge speed of single-point grounding is the fastest. However, there are two exceptions:
Now, you must understand the usage of shielded cable, if you still don’t know how to ground the shielding wire, you can enter Henan Shenbei Industrial Co. Ltd., which sells all kinds of control cable, house wiring cable, communication cable, and instrument cable. 24-hour customer services are also waiting for solving all of your questions.
We can design and manufacture various cables according to your requirement of special cable construction and special occasion and usage.