The rated voltage and insulation voltage of control cables are two important parameters related to the electrical performance of cables. There are significant differences in their definitions, purposes, and emphasis, as follows:
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Rated voltage (U ₀/U)
The rated voltage is determined during the design and use of control cablesReference voltage parametersThe maximum voltage value that a cable can operate safely for a long time, usually expressed in the form of "U ₀/U" (unit: kV).
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among which,U₀The voltage between the cable conductor and the shielding layer (or grounding part);
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URefers to the voltage between the conductors in a multi-core cable (or the ground voltage of a single core cable in a system).
For example, the common rated voltage of control cables is "0.45/0.75kV", which means that the conductor and shielding layer can withstand 450V for a long time, and the conductor can withstand 750V for a long time.
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Insulation voltage (Ui)
Insulation voltage is a measure of the insulation layer of a cableAbility to withstand short-term overvoltageThe parameter refers to the maximum test voltage that the insulation layer can withstand under specified conditions (usually short-term power frequency voltage or impulse voltage), used to verify whether the insulation strength of the insulation material is qualified.
It does not directly correspond to the long-term operating voltage of the cable, but reflects the insulation layer's resistance to breakdown during faults or tests.
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Rated Voltage：
It's about cable selectionCore BasisIt directly determines whether the cable can operate stably in a specific circuit for a long time. For example, when the working voltage of the control circuit is 220V, a control cable with a rated voltage not lower than this value (such as 0.3/0.5kV) needs to be selected.
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insulation voltage：
mainly used forInsulation performance verification and safety designEnsure that the cable does not break down when encountering short-term overvoltage (such as operating overvoltage, lightning induced overvoltage). For example, a cable with an insulation voltage of 1kV needs to undergo a 1kV power frequency withstand voltage test (usually lasting for 1 minute).
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Normally, cablesInsulation voltage higher than rated voltageThis is because the insulation layer not only needs to withstand long-term operating voltage, but also needs to withstand short-term overvoltage, so there will be a certain margin of insulation voltage in the design.
For example, a control cable with a rated voltage of 0.45/0.75kV may have an insulation voltage of 1kV or higher.
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When selecting, attention should be paid to both: the rated voltage should match the long-term operating voltage of the circuit, and the insulation voltage should meet the system's tolerance requirements for short-term overvoltages to avoid safety accidents (such as short circuits and leakage) caused by insufficient insulation.
This article is generated by AI