Recently in one of our facility, use of aluminum conductor for the incoming TPN isolator has developed loose connection in Neutral line and eventually got opened. Which finally resulted in failure of many single phase equipments. How to avoid it and protect these equipments.

In Hazardous area. ATEX (Flame proof) socket are used. where chances of loose supply are open wire is rare. Proper trained wireman / electrician required to do the work. If workmanship poor we that is not in designers hands. That is Quality of Workman ship.

CK,

You need a "Neutral to Ground Voltage Monitor", that will alarm and/or trip when this voltage exceeds your limits indicating that the integrity of the neutral to ground connection is in question. Since we do not know your exact system configuration I suggest that you Google on the above phrase and choose a product that meets your requirements.

Alan

In most cases an Infrared Thermographic Scan will show overheating due to a loose connection and should be performed periodically on your electrical distribution system.

When possible, It is advisable to Earth Neutral at multiple places all along its travel from start to end.
You can connect Neutral to Earth in Every Distribution board and Sub-distribution board and in switch boards.