Issues regarding the insulation of the shield and armor layers of instrument cables
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Dear managers, recently, when inspecting the delivered cables, insulation tests were conducted using a 500V megohmmeter. It was found that the insulation resistance between the cable’s shielding layer and armor layer was less than 1 MΩ. Since many cables exhibited this issue, we sent a letter to the manufacturer requesting clarification and the return of those cables. However, the manufacturer replied that the standard it follows is “TICW/06-2009 Computer and Instrument Cables”, and this standard does not specify any requirements regarding the insulation resistance of the armor layer and shielding layer. Regarding this, I would like to ask the fellow sea users: 1. Should the standards for determining whether a cable manufacturer’s products are of qualified quality be based on GB, since national standards are the main benchmarks for such evaluations. 2. Are there any corresponding GB standards that provide theoretical support for the insulation testing of cable armoring and shielding layers? Could you please provide the names and numbers of such standards? Thank you. I kindly ask all of you to give your strong support in this regard
What is the armor layer of a cable? I really don’t understand
Why is it necessary to measure the insulation of the armor layer and shielding layer? Armor also has a shielding effect, so what is the purpose of testing their insulation? I want to learn * it too
What this article emphasizes is the value of the insulation resistance.
1. The standard for ensuring that products manufactured by cable manufacturers meet quality requirements is that GB standards must be followed. 2. As for the insulation testing of the cable’s armor and shielding layers, it is necessary to verify whether there are corresponding GB standards to provide theoretical support for this; a response can only be given after this has been confirmed
It’s kind of interesting. I think the armor and shielding are in direct contact sometimes, so the insulation resistance isn’t very high.
Thank you to all our customers for their support. Here is some clarification: 1. Armored cables are used for direct burial installation. 2. There is an insulating layer between the armored layer and the shielding layer. 3. The insulation between these two layers is important because their grounding systems are different; if this insulation is inadequate, it may cause problems with the control system
Armored instrument cable: the armor layer is connected to the safety ground in the control room, while the shielding layer is connected to the instrument ground. Safety and instrumentation are essentially combined, and an insulation resistance of around 1 M ohms should not have any impact on the control system.
Don’t you have a technical agreement for cable procurement at your company? Wasn’t the applicable specification agreed upon? If nothing has been done, it doesn’t matter, because computer cables need to comply with the manufacturer’s specifications. I don’t recall any specific provisions in the standards regarding the insulation between the shielding layer and the armor layer; what exists between them is a jacket layer, not an insulating layer. A value of 1 megohm is already very good – what more is expected? The motor can operate fine with a value of 0.5 megohm.
The shielding layer is not grounded; he didn’t even finish high school. It’s the magnetic field of the shielding layer that affects the cable, so it doesn’t matter whether the armor layer is grounded or not. Which damn standard requires grounding of the armor layer? If it really needs to be connected to the manufacturer, copper wires have to be designed for this purpose – have you seen that?
Whether the tube is insulated or not – as long as it doesn’t kill anyone with electricity, that’s fine. But if it does kill someone, there are insurance companies that will cover the costs. Right? :P. . .