Abstract: A programmable, variable volume and pressure, coolant system regulating the amount of coolant flow to a cutting tool by controlling the speed of a coolant pump, and is comprised of a fluid control unit and an electrical control panel. The fluid control unit includes a pump and a AC pump motor operatively connected thereto. The electrical control panel includes: a power supply; circuit breakers; a computer; a variable frequency drive; control relays; and a junction block for making electrical connections to the control panel. The computer receives signals from the tool and a pressure transducer, and is programmed with information concerning the total flow area of the coolant orifices. Using this information, the computer determines an ideal pump speed, and sends a control signal to the variable frequency drive which in turn determines the pump motor speed. The coolant supply system also includes: a coolant supply line for routing coolant from the pump to the tool; a catch pan for collecting recycled coolant from the tool; a filter for removing impurities from the used coolant; a reservoir for storing coolant; and a return line for routing the recycled coolant to the reservoir and from the reservoir to the pump inlet.

Abstract: It is necessary to present a motor repair specification for the repair of low voltage polyphase induction motors intended for PWM inverter application. The specification must approach electric motor repair from the standpoint of maintaining efficiency, not damaging the electromechanical components of the machine, and improving the insulation system. Through the use of the specification, an electric motor should be able to withstand most inverter duty environments upon completion of repair and commission. The purpose of this paper is to present a recommended repair specification meant to reduce the chance of inverter duty failure on repaired low voltage polyphase induction motors.

Abstract: A control system for a vacuum milking system (10), and method of controlling vacuum in such milking system (10). The system (10) comprises an electric vacuum pump motor (14), a vacuum transducer (22) for providing an output signal that varies as a function of changes in vacuum in the milking line (20) and a variable frequency drive (VFD) (16) connected to the vacuum pump motor (14) and the transducer (22) for controlling the speed of the motor (14). The VFD (16) varies the frequency of the power signal it provides to the motor (14) as a function of deviation between the output signal from the transducer (22), which the VFD (16) is programmed to recognize as representative of vacuum, and a setpoint representative of vacuum.

Abstract: With the wide use of power electronics equipment such as rectifiers, inverters, cycloconverters and SCRs in power system control, as well as the off-on switching of voltampere compensators in transmission and distribution systems, electric utilities have experienced an increase in the levels of harmonic frequencies on the electrical delivery system. The off-on switching of the equipment may produce damped transients of high and/or low frequency on the voltage and/or current waveforms. This paper presents a new application of the linear Kalman Filtering Algorithm (KF) for identifying the amplitude and damping factors of these transients (subharmonics). The frequencies of these subharmonics are assumed to be known in advance and are fractions of the system nominal frequency (power frequency). Modelling of these transients to fit the linear Kalman filtering algorithm, as well as the methods of identification are also offered in the body of the paper. The proposed algorithm is applied to actual recorded data of a dynamic load, which is a variable frequency drive controlling a 3,000 HP induction motor connected to an oil pipe line compressor. The data given for this load are the three-phase currents at different motor speed.

Abstract: This paper describes three methods for the detection of rotor damage in an induction motor controlled by a variable frequency drive. They are (i) synchronous sampling of the stator current waveform using phase locked loop circuitry, (ii) time-frequency and wavelet analysis of stator current, and (iii) frequency spectrum analysis of the instantaneous input power of the motor. Experimental results from the three methods are presented. Some conclusions are drawn for the application to condition monitoring.