by Charles Gonzales Gagui - CleVer Vibration
Electrical systems are prone to unwanted interference of electrical signals that engineers always want to avoid. They call it noise in electrical circuits. These noise are not sounds that you can hear, but rather they are random fluctuation in electrical signals. These noises can be generated by electronic devices from within the control panel or from external sources. They could also be temporary or continuous.
Such devices can be a thyristor.
A thyristor is a typical source of noise. During turning off, these devices causes sharp inverted spikes, which we call ‘notching' that produces noise to electrical systems. Figure below shows a waveform disturbance of a thyristor in the incoming voltage side of the control panel.
The pure sine wave (traced in yellow) carries no harmonics, in the distorted sine wave (traced in red) harmonics are present. This voltage waveform is very badly distorted (18% Total Harmonic Distortion, TDH). Surges like these are circumstances engineers want to prevent. During harmonic test, removing the background harmonic distortion, control panel only allows 5% TDH as acceptance level.
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| Photo: Power quality analyser.with my hand |
Electrical systems are prone to unwanted interference of electrical signals that engineers always want to avoid. They call it noise in electrical circuits. These noise are not sounds that you can hear, but rather they are random fluctuation in electrical signals. These noises can be generated by electronic devices from within the control panel or from external sources. They could also be temporary or continuous.
Such devices can be a thyristor.
A thyristor is a typical source of noise. During turning off, these devices causes sharp inverted spikes, which we call ‘notching' that produces noise to electrical systems. Figure below shows a waveform disturbance of a thyristor in the incoming voltage side of the control panel.
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| Photo: Wave form distorted by notching. |
