Insulation requirements for the armor layer and shielding layer in armored control cables and armored signal cables
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The cable models are: KVVRP22 and KYJVRP22, 450/750V steel-sheathed shielded cables. PS: The insulation between wires, between wire pairs and shielding, and between wire pairs and the steel armor is all infinite. The current issue is that the insulation between the steel armor and the shielding layer is 0. Are there any relevant specifications or standards that set requirements for the insulation between the steel armor and the shielding layer? These national standards—2952, 9330, 50217, 50057, 50150, and 50093—do not provide any clear specifications. I would appreciate advice from those with more experience.
An insulation value of 0 between the steel armor and the shielding layer is normal; one serves a shielding purpose while the other provides mechanical protection. Since they are in close contact, no insulation is required between them
There must be insulation between the steel tape armor and the shielding layer of 10kv high-voltage cables； No insulation is required between the steel tape armor and the shielding layer of the shielded control cable.
However, based on the grounding details provided by the design institute: the steel armor is connected to the protective ground, with grounding at both ends; the shielding is connected to the working ground, with grounding at one end. If the steel armor and the shielding are connected together, then is it considered multi-point grounding? ?
Under normal circumstances, the steel armor and shielding are connected to each other, as there is a common grounding point at one end of the distribution room. Only by disconnecting the grounding wires can the insulation between them be tested, thereby determining whether there is insulation between the cable’s steel armor and shielding layer. If there is insulation, then the cable is in good condition; otherwise, the cable is damaged.
That can’t be right; the shielding layer and the steel armor layer of a cable must be insulated from each other, and there is an insulating layer between them. If both the shielding layer and the steel armor layer were conductive, then why go through all this complexity? Wouldn’t using steel strips alone suffice?