Magnetic and non-magnetic effects on cable current carrying capacity
Magnetic and non-magnetic influence on cable current carrying capacity atltech P magnetic and non-magnetic's impact on cable current carrying capacity, steel tape armoured single-core power cable in use there are a lot of limitations, is unreasonable in the structure, concrete analysis is as follows.
By 'electromagnetic field', when the normal operation of steel tape armoured single-core cable, the conductor will be through a lot of alternating current (
Frequent start-stop dc cable line is also quite so by alternating current)
, so will produce a lot of alternating electromagnetic field around the cable, and armoured with steel belt has a good permeability performance, in operation, the steel belt and secondary coil conductor is similar to the current transformer is Lord, when have alternating electromagnetic field through the steel belt, will be induced, alternating current and the resistance of the steel belt itself has is larger, cause fever itself, thus in the steel belt formed in the eddy current loss and magnetic hysteresis loss, so in a very short period of time, and the steel belt can produce high temperature, plus a conductor of heat generated during normal operation, if not timely heat out (
Such as buried)
, cable insulation layer melts or will lead to accelerated aging, damage the insulation of the cable, which result in cable breakdown or scrap in advance.
At present, there are a number of domestic enterprises for single-core armoured by steel wire armoured cable and wire isolation structure, actually this kind of 'magnetic isolation structure is not reasonable, the structure of the magnetic separation purpose is to increase the magnetic resistance of magnetic circuit, reduce the wire in the magnetic induction intensity, so as to reduce the wire loss, but in actual operation, the copper wire can cause the distortion of field lines, and not break lines, that is to say and can't achieve the goal of increasing the magnetic resistance, concrete analysis can be found in the Shanghai electric cable research institute, a senior expert professor guo-dong ma's thesis the structure of steel wire armoured single-core power cable armoring of study' and 'wires carrying capacity'.
In the electric wire electric cable current carrying capacity 'professor guo-dong ma through a large number of trials show that single core cable using steel wire armoured with copper wire isolation structure will reduce the carrying capacity of the cable (
Note: the water low cable laying out of place in the discussion)
, but due to the steel wire armoured cable are able to sustain large tensile stress, is still widely used at present.
Therefore, for single core cable, we can not use a magnetic material armoring, and should consider to replace with nonmagnetic materials, such as copper wire (
, stainless steel wire,
, aluminum alloy wire (
And so on.
To this, the sales department during the process of contact the customer, if there are any customer to require the use of steel tape armoured single-core cable structure, single core cable should be as far as possible to the customer stated, reason why cannot adopt steel tape armoured and armoured cable preferred recommended the use of magnetic materials.
The Caledonian gloria Tony cable co. , LTD. , Shanghai office contact person: ms zou Websitehttp / / WWW.
Com sohu blog: HTTP / / caledonianpenny.
Com [atltech edited]