Measuring the insulation resistance of power cable

1, the measurement of 10kV power cable, the choice of megohmmeter? Use should be made before check?
Select the 2500V megger one (with the test line), the megohmmeter horizontally, first instrument appearance inspection and open circuit and short circuit test did not confirm the connection before, megger intact.
Shake the wiring method measured should be correct (first discharge should be prior to connection).
The shake test project is on the interphase and insulation resistance value, namely U V, W, V, W, U; U, V; W, to. A total of three times.
Measurement of 10KV power cable connection
2, for 10kV power cable insulation resistance are required?
The judgment standard of qualified shall be as follows:
(1) length in 500m and below 10kV power cable, measured with 2500V megger shake, in cable temperature of +20 DEG C, the value of insulation resistance should be not less than 400M.
(2) among the three, the value of insulation resistance is consistent; if it is not consistent, then the unbalanced coefficient of not more than 2.5.
(3) determination of the numerical value and the last measured, converted into the same temperature. The value of not decline more than 30%.
3, the measurement of 10kV power cable in a run in the whole course of the (by operating sequence answer, including judge the cable whether can continue to run. Safety measures should be sufficient).
Measuring methods and steps are as follows:
(1) cable after power failure, advanced by line phase discharge, discharge time of not less than 1min, cable longer larger capacitance is not less than 2min.
(2) used a soft cloth dry, clean, wipe the dirt near the cable core.
(3) connection according to the requirements, should be correct. Such as shake measure relative isolation, will be measured phase shield is connected to megohm table "G" terminal; the non measured phase two wire core is connected and then connected with the cable metal sheath after the common ground, and will lead the common grounding connection in megohm table "E" on the terminal; a test wiring in megohm table "L" terminal, the test line ("I." The other end of line) at this time is not the wiring core.
(4) the insulating part hold the "L" test line with a person, another person turn megohmmeter crank up to 120r/min, the "L" line and the line core contact for 1 minutes (a stable reading). Record the value of insulation resistance.
(5) the "L" line to evacuate the line core, stop turning the handle, and then discharge.
Shake the safety precautions in the test:
(1) shake measure before and after shake measure should discharge;
(2) megohm shake table handle, speed should be worthy of shoes keep ratings, more shall not be less than the rated speed 80%;
(3) the other end of the cable must be safety measures, do not allow the people close to the measured cable, not to cause reverse feeding electrical accident;
(4) in order to ensure the safety instrument. To do the megger shake to 120r/min, then the megohm table "L" line is connected with the measured cable core, evacuation test line "L" rear can stop shaking handle.