How to check the insulation of wires

You will need
  • - megohmmeter;
  • - Electrician with a security group III or IV.
Instruction
In order to checkisolationwires, find experienced electricians with a safety group of at least III or IV. When carrying out all the work, be guided by the Rules for the Installation of Electrical Installations (ПУЭ) and the Rules for the Technical Operation of Electrical Installations of Customers (ПТЭЭП).
Pick the right device. To measure the insulation resistance of the cable section of less than 16 square meters. mm, take a 1000 V megohm meter, and a 2500 V for a thicker or armored cable. The insulation of any wire can be measured with a 1000 V megohm meter.
To checkisolationelectrical wiring with an insulation resistance of less than 1 MΩ, test them with alternating current voltage of 1 kV of industrial frequency. In order for the measurement results to be official, the instruments must pass an annual verification in the bodies of the Gosstandart of the Russian Federation.
Please note that measurements should be carried out at an insulation temperature above + 5 ° C and with a low degree of moisture. To find out the degree of moisture, calculate the absorption coefficient by dividing the measured insulation resistance one minute after applying the voltage of the device to the insulation resistance 15 seconds. This ratio should not differ from the factory data by more than 20%.
Connect the megohmmeter to the wire using flexiblewireswith restrictive rings in front of the contact probes and handles at the ends for insulation. The smaller the connecting wires, the more accurate the measurements, the resistance of their insulation should not be less than 10 MΩ.
Before starting the measurements, check the test object, there should be no voltage on it. If necessary, carry out grounding (after connecting the device).
At the point of connection of the device, cleanisolationfrom dirt and dust. Connect the wire to the sockets of the megohm meter. Select the output voltage that will match the test wire or cable.
If you measure insulation resistance using a generator-type device, rotate the generator handle at a speed of 120-140 revolutions per minute.To start the digital meter, just press the button.
Take readings and record. If there are several measurements, after each remove the capacitive charge, grounding those parts of the object to which voltage was applied.


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