High rupture fuses

The equipment and connections are simple and the starter is robust. The basic equipment will comprise an isolator, high rupturing capacity fuses, a contactor, overload devices and control switches. 

Main motors need starter overload and short circuit protection. High rupture fuses (HRC) will protect the motor against short circuit conditions, and will interrupt the electrical supply in milliseconds of the fault occurring. It is essential that fuses of this type are always fitted. Conventional overload protection, thermal or magnetic, can offer no protection to a motor with an extended acceleration time. Thermistor overload protection is the only true protection for a motor under these conditions. A thermistor is embedded in each of the motor s three windings and connected in series. The resistance of these thermistors is designed to increase rapidly at a set temperature, depending upon the insulation class of the motor. The thermistors are connected to an electronic amplifier control unit in the starter enclosure, and will trip the starter contacts when required. The device will not reset until the motor has sufficiently cooled. 

Properties Rupture modulus up to 50,000 psi, d 2.5, thermal shock resistance 900C, highest continuous-use temperature 700C. Glass ceramics lie between borosilicate glasses and fused silica in high-temper-ature capability. 

Methanolysis of sodium or lithium clavulanate provides a high yield of the pyrrole (79) 52,53,54). Since the enamine (78) has also been isolated a fairly well defined degradative pathway for the formation of (79) can be postulated further verifying the fused p-lactam-oxazolidine structure of clavulanic acid. Rupture of the P-lactam followed by fragmentation of the oxazolidine (76) would lead to the keto acid (77) decarboxylation provides... 

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