How is 'pressure test' cable SXXLJT P cable withstand voltage test is a kind of ac voltage test, also can call work frequency withstand voltage test.
Ac withstand voltage test is applied on the insulation of the cable products is higher than the working voltage is the rated voltage must be a multiple of voltage values, to keep the insulation of the cable within a certain period of time will not be breakdown.
For those that will be used in the insulation of the power transmission cable products, each product before the factory has to be a pilot.
Pressure test aim is to review the product under the working voltage operation reliability and relative timely in order to can find flaws in insulation.
But its main production technology in order to discover the defect point.
For example: on the conductor insulation of external injury, can make the electric field produces a sharp distortion of serious defects, and so on.
Pressure test voltage cable selected principle is: either found serious flaws in insulation, at the same time also will not cause damage to the insulating case, so that the direct cause insulation perceptible.
Pressure is about minutes of general cable products.
Pressure test equipment requirements: the frequency of the test voltage should be between Hertz to hz ac voltage, voltage waveform must close to the sine wave, the ratio between the peak and RMS values according to the test voltage value of the sample and product standards requirements of the pressure of time reference.
Next we learn about the pressure test of concrete operation method.
The first test sample preparation:.
Experiment method of the length of the terminal part and draft terminal head must ensure that the prescribed under the pressure test voltage cable there won't be along its surface discharge or internal breakdown happens.
If need within the tank experiment, experiment of two end out of the water can not be less than the length of the mm, and make sure under the specified test voltage along the surface discharge will not happen.
Withstand voltage test steps: test steps must meet the rules of operating the pressure test requirements can be performed.
When the withstand voltage test, pressure test the difference between the temperature and the temperature of the surrounding environment cannot exceed ℃.
Voltage should be started from the lower end, slow and relatively flat on the ground to the test voltage specified in value, and the pressure of time stipulated in the need to maintain.
In lower voltage, until reduced to the cable specified in % of pressure testing voltage value, and can cut off the power and the experiment is absolutely not allowed in the case of high pressure and down suddenly cut off the power supply, this is done to avoid overvoltage.
Voltage test evaluation: test cable continues to exert test within the prescribed time, as cable without any breakdown phenomenon occurs, you can think this experiment by the power frequency withstand voltage test.
But if during the process of test, or the end of cable terminal happened along its surface discharge or internal breakdown situation, also can allow the other to end connection, and repeated test.
Unless written has special provisions in the product standard, all the cable withstand voltage test process needs to be time.
When tested during the process, if because the power to suspend the withstand voltage test, when to continue the test, unless there are special provisions in the product standard, other experiments must time again.
Note: ac withstand voltage test.
Test equipment need on a regular basis to check;
Withstand voltage test loop should be equipped with fast overcurrent protection device, the purpose is to ensure the breakdown occurs when the pressure test and some special cases, can be quickly removed the power of the test.
In pressure test should be equipped with grounding metal fence around the area, the location of the inlet and outlet pressure test on the cable area have chain control, signal lamp and has 'the high voltage danger' warning signs, and so on a series of safety measures.
In the area of pressure test should be equipped with ground wire, earthing resistance must be smaller than the ohms.
The earthing end of the step-up transformer and test cable grounding at connection or attach electrodes can be reliable connection and grounding.
Above is the principle of small make up through the pressure test, equipment requirements, methods, and matters needing attention these four aspects of pressure testing cable pressure test are introduced in detail for you.
Believe that everybody on the experiment of know already, if there are any questions, welcome to our 'Shen Xing cable group' technology related consulting service.