Harmonic Filter Function (Available in the 30032A)
1. What is a Harmonic?
Harmonic refers to sinusoidal quantity having a frequency that is an integral multiple of the fundamental frequency (for example, the commercial frequency). When a harmonic is superimposed on the fundamental frequency, the waveform is distorted.
2. Why is it Necessary to Accurately Measure the Leakage Current of the Fundamental Frequency (Commercial Frequency)?
One problem when measuring the leakage current to check the isolation of electrical circuits in power distribution equipment is that the electrical isolation cannot be correctly understood due to the influence of a harmonic current. That is, the leakage current flowing from the electrical circuit to ground is very small so that, in order to check the isolation of electrical circuits by means of the leakage current, it is necessary to remove the harmonic component of the leak current and measure only the current of the fundamental frequency (commercial frequency).
3. The 30032A Employs a Harmonic Filter
Conventional leakage clamp-on testers could not sufficiently remove harmonic current components so measured leakage current values were often larger than the specified value due to the influence of a harmonic current. In this case, retesting with an insulation tester was required, resulting in increased effort and cost for the test. Under these circumstances, Yokogawa Meters & Instruments Corporation has developed the leakage clamp-on tester 30032A, which employs a high-performance harmonic filter that can accurately measure just the fundamental frequency component of the leakage current.