Protection voltage surges

The higher Ihe value of C. the lower will be the voltage overshoots in the rectified voltage and the inverter circuit would be fed by an almost cotistant voltage soitrce. The capacitor iti the circuit also provides an indirect protection from the voltage surges. 

It has been seen that smaller rating HT machines are more susceptible to steeply rising voltage surges, compared to larger ratings, due to their relatively w eaker interturn insulation and require more careful attention to their adequate protection. We attempt to explain this phenomenon as follows ... 

Protection for the machine should be such that the voltage surges and their rise limes, whenever they occur in the system, shall fall within this envelope of the machine. (Refer to Section 17.10 for a total surge protection.)... 

For adequate protection of the machine it is essential to know the amplitude, F, and the rise time, /, of the severest voltage surge (FOW) that may occur on the system. It is recommended that the actual field tests be conducted for large installations according to the recommended simulation test circuits, noted above, to ascertain these surges. 

Power Supply Protection—Provide suitable power supply protection/conditioning equipment if the equipment is susceptible to power brownouts, voltage surges/spikes, or line conducted electromagnetic interference. 

The leak monitoring system must therefore be supplied with equipment which can divert voltage surge on the buried components and protect people and the control and assessment system. An independent expert inspector must have examined and reported on the lightning prevention equipment. 

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