Development of a test bench for testing the power cable of electric pumps - Page 1
Forum section: electronics / projects

author: daniyl_rus
author_rank: Newbie
timestamp: May 08, 2025, 03:33:41 pm
content: Hey guys im about to graduate from MPEI so i wanted to ask you for some help with my diploma. My subject is to create a test bench for testing the power cable for electric pumps. Electric pumps that im talking about is those pumps that should be >200m deep in the water and pump oil or other stuff. The thing is that im already on a stage when i should start to draw electric schemes of my future stand, but i have no idea where to start and what should i actually draw. Im sorry for my not perfect english, but ill try my best to communicate correctly so you can understand what is the main point of my speech. If anyone would like to help ill appreciate it, or if there is someone who actually worked with some of these kind of oil pumps i would absolutely love to hear something about them that can help me with my diploma.

author: jwet
author_rank: Frequent Contributor
timestamp: May 08, 2025, 04:27:46 pm
content: I'll try to get a conversation started-Other than the obvious to measure resistance from end to end, I would also measure R at a moderately high current (a few amps up to your rated current)- this should show up workmanship issues.You might consider mechanical pull tests for strain relief, etc.HiPot leakage tests are a standard kind of test- look at Biddle or Megger for methods and equipment. You bascially put a high voltage on the wires and measure leakage current, sometimes over a period of time like 10 minutes, some of the failures develop slowly.Something that might look sexy to an academic audience would be Time Domain Reflectometry. You send a high frequency pulse town the cable and look for reflections, this should show up discontinuities, etc. You can build a TDR with an oscilloscope and a pulse generator. I built a portable one in the 90's that won Circuit Cellar's design contest. It was for network cabling.Good Luck- better get to work!

author: themadhippy
author_rank: Super Contributor
timestamp: May 08, 2025, 04:45:25 pm
content: As mentioned above insulation resistance and conductor continuity are the most important for power cables,but as the cable is meant for use ar depth youd maybe need to think about also simulating the environment the cables going to be operating in whilst testing.

author: SeanB
author_rank: Super Contributor
timestamp: May 08, 2025, 07:09:06 pm
content: Standard for insulation test on these cables is a bath of salty water, so you can find any pinholes in the insulation. You place the cable in the salt water with the ends out of the water, and do the high voltage insulation test between the conductors (both connected together at one end only) and the water in the bath, normally a stainless steel tub. any leakage of water will show up as a low resistance result, instead of the expected greater than 1M resistance at 500V that is the expected result for a good cable.Testing resistance at a current around the operate current is best, using a transformer, around 6VAC, and measuring the resistance using the voltage drop across the cable, and the current flow in it. Should be within the range for the manufacturer spec for that diameter and conductor type cable, a high or open showing the cable has been either bent and broken internally, or been stretched excessively. Test for a short between cores with the insulation test, as you typically do the resistance test with only one end, shorting the far end together, so a lower than expected resistance shows an internal short, even before the high voltage and cable insulation test, though all tests can be done with the cable in the bath, and with both ends out of the water, only opening the far side short for the insulation test between the cores.

author: daniyl_rus
author_rank: Newbie
timestamp: May 11, 2025, 12:57:38 pm
content: So what should my functional scheme should be including in themselves? At first ofc it is a voltage source, some kind of a hermetic chamber where we can reproduce conditions that our cable will be during expluatation (like salt water, high temperatures, and etc), current and voltage measurement, thermometer, and load. What else should be included, what do you think?