Insulation resistance is measured with a megger, which applies a high DC test voltage and reads the leakage resistance of the insulation between conductors; healthy insulation should give a very high value in megohms.

For a feeder in good condition the readings between the different phase pairs should be both high and reasonably consistent with one another, showing uniform, undamaged insulation.

Here the three readings are 60 MΩ, 58 MΩ and 61 MΩ, all large and within a few megohms of each other, which is exactly the pattern of sound, well-maintained insulation.

If insulation had broken down there would be a very low reading, often near zero, on the affected pair, so no low value here means no insulation fault and no need to replace the cable.

An open circuit is a break in continuity, not a fall in insulation resistance, so the megger cannot reveal it; that is checked with a continuity or resistance test instead.

An inter-turn short in the motor winding would show up as a very low resistance or a continuity/inductance change, again not as three uniformly high figures like these.

Hence, the answer is The insulation between phase conductors is satisfactory.