Flex Testing for Lift Cables

Given the type of installations and equipment where lift cables are used, they need to be able to withstand constant and rapid movement and flexing without failure. This test is specifically designed to replicate that rapid back and forth flexing under electrical load to determine their suitability for the task.

The test apparatus sees two carriages mounted at the same height, with the cables attached to them moving horizontally towards and away from each other in simple harmonic motion. Both the carriages travel at the same speed, up to a maximum relative acceleration of 4m/s². The test criteria states that the cable must complete 1500 +/- 10 cycles per hour, with a cycle being determined as moving from the outermost position to the innermost position, and then back to the outer point again. 

The test is conducted over an extended period of time, with the cable subject to 3 million flexing cycles in total. The test is interrupted once per week to perform a high voltage test on each of the cable cores, with any flash-over or insulation breakdown regarded as a failure.

It is only after the 3,000,000 cycles are complete on the flex test, and where there are no open circuit failures on any of the conductors, that the lift cable can be considered to have passed the test.