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An integrated fan drive system for a cooling tower comprising a high-torque, low speed permanent magnet motor having a rotatable shaft, a fan comprising a hub that is directly connected to the rotatable shaft and a plurality of fan blades that are attached to the hub, and a variable frequency drive

An integrated fan drive system for a cooling tower comprising a high-torque, low speed permanent magnet motor having a rotatable shaft, a fan comprising a hub that is directly connected to the rotatable shaft and a plurality of fan blades that are attached to the hub, and a variable frequency drive device in electrical signal communication with the permanent magnet motor to control the rotational speed of the permanent magnet motor. The high-torque, permanent magnet motor comprises no more than two bearings in operative association with the shaft. The variable frequency drive device has a variable frequency controller that has an input for receiving AC power and an output for providing electrical signals that control the operational speed of high-torque, permanent magnet motor. The variable frequency drive device also includes a user interface in electronic data signal communication with the variable frequency controller to allow a user to input motor speed control data.

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1. A drive system for driving a fan in a cooling tower, the fan comprising a fan hub and fan blades attached to the fan hub, the drive system comprising: a high-torque, low speed permanent magnet motor comprising a motor casing, a stator and a rotatable shaft, the rotatable shaft being configured fo

1. A drive system for driving a fan in a cooling tower, the fan comprising a fan hub and fan blades attached to the fan hub, the drive system comprising: a high-torque, low speed permanent magnet motor comprising a motor casing, a stator and a rotatable shaft, the rotatable shaft being configured for connection to the fan hub, the motor further comprising a dual bearing system consisting of a pair of radial bearings that locate and support the rotatable shaft relative to the motor casing; anda variable frequency drive device to generate electrical signals that effect rotation of the rotatable shaft of the motor at a rotational speed in order to rotate the fan. 2. The drive system according to claim 1 wherein the variable frequency drive device comprises electronic circuitry for receiving control signals that represent a particular rotational speed and generating electrical signals for the permanent magnet motor, wherein the electrical signals represent the rotational speed represented by the received control signals. 3. The drive system according to claim 2 further comprising: vibration sensors located within the motor casing to measure vibrations at the radial bearings and output signals representing the measured vibrations; anda plurality of heat sensors located within the motor casing to measure heat at the stator and at the radial bearings, the heat sensors outputting signals representing the measured heat. 4. The drive system according to claim 3 further comprising a processor for generating speed control signals for input into the electronic circuitry of the variable frequency drive device, wherein the speed control signals vary the speed of the high-torque, low speed permanent magnet motor, the processor being configured to process the signals outputted by the vibration and heat sensors to determine vibration level and stator heat, respectively. 5. A method of installing a new fan drive system in a wet-cooling tower having a fan assembly that comprises a fan hub and a plurality of fan blades that are attached to the fan hub, the wet-cooling tower also having a preexisting fan drive system for driving the fan assembly, wherein the preexisting fan drive system has a gearbox, a drive shaft that drives the gearbox and an induction motor that drives the drive shaft, the method comprising: disconnecting the gearbox from the fan hub and removing the gearbox;removing the drive shaft;removing the induction motor;providing a high-torque, low speed permanent magnet motor comprising a motor casing, a stator and a rotatable shaft, the motor further comprising a dual bearing system consisting of a pair of radial bearings that locate and support the rotatable shaft relative to the motor casing; andconnecting the rotatable shaft of the motor to the fan hub. 6. The method according to claim 5 wherein the permanent magnet motor has a plurality of heat sensors located within the motor casing to measure heat at the stator and heat at the radial bearings. 7. The method according to claim 6 wherein the permanent magnet motor includes vibration sensors located within the motor casing to measure the level of vibrations at the radial bearings. 8. The method according to claim 5 further comprising the steps: providing a variable frequency drive device to power the permanent magnet motor; andelectrically connecting the variable frequency drive device to the permanent magnet motor. 9. A wet-cooling tower comprising: a fan deck;a fan cylinder positioned upon the fan deck;a fan assembly located within the fan cylinder, the fan assembly comprising a fan hub and a plurality of fan blades connected to the fan hub;a basin for receiving water;a high-torque, low speed permanent magnet motor comprising a motor casing, a stator supported by the casing and a rotatable shaft, the rotatable shaft being connected to the fan hub, the motor further comprising a dual bearing system consisting of a pair of radial bearings that locate and support the rotatable shaft relative to the motor casing;a plurality of heat sensors located within the motor casing to measure heat at the stator and heat at the radial bearings and to output signals that represent the measured heat;vibration sensors located within the motor casing to measure the level of vibrations at the radial bearings and output signals that represent the level of vibrations;an air-flow sensor to measure the air-flow generated by the fan assembly and output signals that represent the level of air-flow generated by the fan assembly;a temperature sensor in the basin to measure the temperature of the water in the basin;a variable frequency drive device in electrical signal communication with the permanent magnet motor to control the rotational speed of the permanent magnet motor, the variable frequency drive device comprising electronic circuitry for receiving control signals that represent a particular motor rotational speed and generating electrical signals for the permanent magnet motor that correspond to the received control signals; anda processor to process the signals outputted by the vibration, heat, air-flow and temperature sensors and generate control signals for input into the electronic circuitry of the variable frequency drive device. 10. A cooling tower, comprising: a fan assembly comprising a fan hub and fan blades attached to the fan hub;a high-torque, low speed permanent magnet motor comprising a motor casing, a stator assembly supported by the motor casing and a rotatable shaft, the rotatable shaft being connected to the fan hub, the motor further comprising a dual bearing system consisting of a pair of radial bearings that locate and support the rotatable shaft relative to the motor casing; anda variable frequency drive device to generate electrical signals that effect rotation of the rotatable shaft of the motor at a rotational speed so as to rotate the fan. 11. A wet-cooling tower comprising: a fan assembly comprising a fan hub and a plurality of fan blades connected to the fan hub;a high-torque, low speed permanent magnet motor comprising a motor casing, a stator attached to the motor casing and a rotatable shaft, the rotatable shaft being connected to the fan hub, the motor further comprising a dual bearing system consisting of a pair of radial bearings that locate and support the rotatable shaft relative to the motor casing;a plurality of heat sensors located within the motor casing to measure heat at the stator and heat at the radial bearings and to output signals that represent the measured heat;vibration sensors located within the motor casing to measure the level of vibrations at the radial bearings, the vibration sensors outputting signals that represent the level of vibrations;an air-flow sensor to measure the air-flow generated by the fan assembly and output signals that represent the level of air-flow generated by the fan assembly;a variable frequency drive device in electrical signal communication with the permanent magnet motor to control the rotational speed of the permanent magnet motor, the variable frequency drive device comprising electronic circuitry for receiving control signals that represent a particular motor rotational speed and generating electrical signals for the permanent magnet motor that correspond to the received control signals; anda processor for processing the signals outputted by the vibration, heat and air-flow sensors and generating control signals for input into the electronic circuitry of the variable frequency drive device.