How to measure the insulation of submersible pump

The important factor is the electric submersible pump application, in this situation, the relevant considerations it is unavoidable, so to do insulation treatment, then how to measure the insulation of submersible pump?
The submersible pump is generally a four core cable with a multimeter to test, the multimeter to the resistance profile, because the three-phase winding is connected in star, so you can use a multimeter to measure three lines are open, the resistance value are smaller and are basically the same, Ohm resistance. This means that the three-phase winding is basically normal. The string to the rest of the same with submersible pump shell, said wire is also connected to the ground, but also in the rest of any of the three thread in a cable with in measuring the resistance, under normal circumstances, should be infinite, which is between the measuring winding insulation with wire, the more better.
In addition to explain the use of multimeter can probably check the submersible pump on insulation, because universal battery voltage meter is not high, so the submersible pump insulation with 500V insulating shake table to detect, at least to normal value greater than 0.5 to be qualified.
In order to better use the submersible pump, we need to do a good job diving pump insulation detection, so as to ensure the safety of our use, so that the work can be carried out smoothly.