Estimation Of Power Factor Research Articles

Smart Technique for Induction Motors Diagnosis by Monitoring the Power Factor Using Only the Measured Current

This paper is concerned with accurate, early and reliable induction motor IM fault detection and diagnosis using an enhanced power parameter measurement technique. IM protection devices typically monitor the motor current and/or voltage to provide the motor protection from e.g. current overload, over/under voltage, etc. One of the interesting parameters to monitor is the operating power factor (PF) of the IM which provides better under-load protection compared to the motor current based approaches. The PF of the motor is determined by the level of the current and voltage that are drawn, and offers non-intrusive monitoring. Traditionally, PF estimation would require both voltage and the current measurements to apply the displacement method. This paper will use a method of determining the operating PF of the IM using only the measured current and the manufacturer data that are typically available from the nameplate and/or datasheet for IM monitoring. The novelty of this work lies in detecting very low phase imbalance related faults and misalignment. Much of the previous work has dealt with detecting phase imbalance faults at higher degrees of severity, i.e. voltage drops of 10% or more. The technique was tested by empirical measurements on test rig comprised a 1.1 kW variable speed three phase induction motor with varying output load (No load, 25%, 50%, 75% and 100% load). One common faults was introduced; imbalance in one phase as the electrical fault The experimental results demonstrate that the PF can be successfully applied for IM fault diagnosis and the present study shows that severity fault detection using PF is promising. The proposed method offers a potentially reliable, non-intrusive, and inexpensive CM tool which can be implemented with real-time monitoring systems

Estimation of Induction Motor Operating Power Factor From Measured Current and Manufacturer Data

Three-phase induction (asynchronous) motors (IM) are industrial work-horses, making the protection of IM a very important topic. IM protection devices typically monitor the motor current and/or voltage to provide the motor protection functionalities like current overload, over/under voltage, etc. One of the interesting parameters to monitor is the operating power factor (PF) of the IM, which provides better underload protection compared to the motor current-based approaches. Traditionally, PF estimation would require both the voltage and the current measurements in order to apply the displacement method. In this paper, we present a method of determining the operating PF of the IM using only the measured current and the manufacturer data that are typically available from the nameplate and/or datasheet. Experimental results are presented to substantiate the feasibility of the proposed method, validated alongside the state of the art PF estimation methods. Operational PF can be effectively used for underload detection, like in a pump application, or PF compensation for improving the power quality.

EFFECT OF THE RIPPLE CURRENT ON POWER FACTOR OF CRM BOOST APFC

Boost Active Power Factor Corrector operating in a Borderline or Critical Conduction Mode is reexamined. Approximate analytical expressions of the inductor RMS current as well as estimation of Power Factor of the APFC are obtained. Based on the proposed theory, the paper suggests simple design criteria for the line filter.