Retorque Check
This is retightening all power connections some time after first commissioning. Conductors settle during the first load and temperature cycles, stranded cores flatten slightly and the pressure from the initial tightening drops. This single maintenance step prevents a large share of faults caused by loose terminals.
A newly made connection settles mechanically during the first hours. Core and terminal surfaces embed into each other at micro scale, and temperature cycles expand and contract the material. As a result the contact pressure from the initial tightening decreases somewhat.
- Timing: the first retorque is done after the system has run at its real load. Common practice is a check in the interval from the first day up to a week; after that it goes onto the periodic maintenance list.
- Torque: follow the torque value the manufacturer gives for the terminal or lug and use a torque wrench. There is no universal torque table; the value varies with terminal type.
- Overtightening: forcing the screw strips the thread and cuts into the stranded core, reducing its cross section. Tighter is not always better.
- Records: note which connections were tightened and when.
Combining the check with a voltage-drop measurement is the most efficient approach: measure under load, tighten the points that come out borderline and measure again.
The context in which this term is used: Installation, redundancy and field continuity