log details

NPM is polling the physical hardware sensors on the router so it can alert about any problems. The ones shown in these screen shots are watching for any power levels (voltage) outside of normal ranges for the router. Voltage going too high or too low could damage the device. 

The second screen shot is monitoring the internal temperature of the router at several points. Temperatures going too high would indicate a possible problem or warn of when high temperature could cause physical damage to the components. 

Being all green/healthy in your case, it doesn't look like there is actually a problem.