Wire and cable cable factory lots power cable for the arrival of the acceptance of knowledge
Cable wire and cable factory lots of power cable for the arrival of the acceptance of knowledge guangdong cable factory industrial co. , LTD. , after delivery of the cable due to the lack of professional knowledge in part of the construction and acceptance, and methods of improperly, often cause qualified acceptance in the construction and acceptance without cable through, for cable manufacturers and buyers are has brought many troubles and cable construction right before and after the acceptance method is each cable should be to master the necessary knowledge, the following will introduce you to the power cable line of rubber and plastic insulated power cable transfer experiment content of the project and some rules of the project: first, the experiment project of power cable line rubber insulated power cable handover testing project content: down 1)
Measuring insulation resistance for main insulation and outer sheath;
The main insulation ac withstand voltage test;
Outer sheath of dc withstand voltage test;
Check at the ends of the cable line phase;
Overlapping interconnected system test;
Cable system of the partial discharge measurement.
The delivery test is used only for ac single core cable.
Rated voltage U0 / U for up to and including 18/30 kv cable, when does not have conditions allow use valid for 3 U0 0.
1 hz voltage applied 15 min or dc withstand voltage test and leakage current measurement instead of ac withstand voltage test.
Test items of part two, 1, measuring insulation resistance measuring insulation resistance shall meet the following requirements: a)
Measuring insulation resistance before and after the pressure test should be no obvious change;
Rubber and plastic cable outer sheath, lining layer of insulation resistance is not lower than 0.
Measurement with a megger insulation rated voltage, appropriate USES the following levels: 1)
Cable insulation measure appropriate USES 2500 v megohmmeter, up to and including 6/6 kv cable above 5000 v megohmmeter is also available.
Rubber and plastic cable outer sheath, lining layer measuring appropriate USES 500 v megohmmeter.
2, dc withstand voltage test and leakage current measurement, shall meet the following requirements: a)
Dc withstand voltage test voltage: 1)
Main cable type under dc voltage withstand test Ut can be used: for insulation (turn-key
: for split phase shield insulation: type: U0 -
Cable conductor to ground or metal test voltage as shown in the table below.
The main cable dc voltage withstand test unit: KV2)
Ac single core cable outer sheath insulation of dc withstand voltage test, can according to the provisions fork interconnected system test.
Test, test voltage can be divided into 4 ~ 6 stage booster, each stage for 1 min, and reads the leakage current value.
E. after test voltage to maintain 15 min, leakage current when reading 1 min and 15 min.
When measured, should eliminate the influence of the stray current.
The main cable leakage current of three-phase unbalanced coefficient (
The ratio of the maximum and the minimum)
Should not be greater than 2;
When more than 6 / l0kV and cable leakage current is less than 20 mu A cable leakage current is less than 10 and 6 kv and below, the unbalanced coefficient does not make the rules.
Leakage current value and unbalanced coefficient as a judgment of insulation condition of reference only, not as a criterion of whether can put into operation.
Other cable leakage current value does not make the rules.
Cable leakage current is one of the following circumstances, cable insulation may be flawed, and should find out the defective parts, and dealt with: 1)
Leakage current is very unstable;
A sharp rise in the leakage current increases with test voltage;
The phenomenon of leakage current with the extension of test time is increasing.