In a three phase power supply with four wires, the wires are coupled to {HEAD ~ three large star connected resistors} having {TAIL ~ different resistance values} 
having
In a three phase power supply with four wires , the wires are coupled to { HEAD ~ three large star connected resistors } having { TAIL ~ different resistance values }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL