Medium-voltage motor

Due to the high power requirements of large extruders, medium-voltage motors are utilized that differ in many aspects from the low-voltage motors utilized in low to mid-range extruders. That is why we distinguish here among different sized extruders. 

Shaft grounding serves to avoid low-frequency bearing currents. It is generally used only on medium-voltage motors. It is expensive and requires frequent maintenance. 

Thanks to their much lower current requirement, medium-voltage motors require conductors with notably smaller cross-sections and can thus be built much more compactly. 

However, because of their notably higher operating voltage, the insulation requirements of medium-voltage motors are considerably higher. 

Figure 17.13 Water-cooled medium-voltage motor with air/water-type heat exchanger...

E16 151P, PROCESS ELECTRICAL EQUIPMENT MEDIUM VOLTAGE MOTORS, ALTERNATING CURRENT. 

Bressani, M., Bobig, P. and Secco, M., A support experimental program for the qualification of safely-related medium-voltage induction motors for nuclear power generating stations. Presented at the International Conference on the Evolution and Modem Aspects of Induction Machines Torino, July (1986). 

Motor efflciency dues not vary much with load. The variation is probably 2-oCf for medium-sized motors (flfl-flOO hp) and for pi-actical purposes can be considered consUmt. So can the power factor and voltage. 

The voltage at which the supply is taken or generated will depend on the demand. In the United States, power is usually transmitted over long distances at 135, 220, 550, or 750 kV Local substations step the power down to 35 to 69 kV for medium voltage transmission and then to 4 to 15 kV local distribution lines. Transformers at the plant are used to step down the power to the supply voltages used on site. Most motors and other process equipment run on 208 V 3-phase power, while 120/240 V single phase power is used for offices, labs, and control rooms. 

Performance tests are those tests that need to be carried out on combined equipment such as a gas-turbine driven generator or a pump driven by a high-voltage motor. In such cases the dynamic relationship between the various equipments is of interest. For example, rotor vibration, critical speeds, run-up time to full speed, starting up and shutting down sequences, full-load and over-load performances, heat dissipation and cooling medium performance. 

Other objeas may be used to describe the function of a motor or drive, a medium voltage circuit breaker, or a heat exchanger a complete reactor may be described as a collection of objects. Emerging standards such as STEP (the Standard for the Exchange of Product Model Data, ISO 10303 [5]) are defining modeis for the interchange of electronic data desaibing all types of... 

The induction motor has been used rehably for production hoists for over 20 years. When it is fed by modern medium voltage PWM drives it provides an ideal solution for hoisting applications. Combined, they provide improved system reliability as well as providing many benefits for the design of the electrical power systems. 

The hoist drive solution presented in this work, which is based on the Ingedrive MVlOO medium voltage AG frequency converters, contains two completely independent Active Front End Rectifier and Inverter sets under the well-known AC-DC-AC topology. The entire drive system solution allows the operation at full speed and full load (then full hoist performance, with no limitation) even in the case that one frequency converter (AG-DC-AC set) is unavailable. The solution presents some extra benefits comparing to the original hoist system solution that was based on two slip ring rotor wound induction motors in which the speed control... 

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