Скачать или смотреть Neutral Earthing and Grounding

Neutral Earthing and GroundingNeutral earthing and grounding serve one and the same goal. These techniques keep people safe from electric equipment and electric shocks if such equipment is alive due to damaged insulation. Neutral grounding has the following nature: If insulation is damaged, the circuit occurs as follows: transformer's input phase winding - phase conductor - device - the point of frame fault - protective conductor - neutral point of the transformer's secondary winding. A single phase circuit occurs and the current strength increases sharply. An automated fuse actuates (the conducting element burns out) switching off the device with a damaged insulation. This is exactly what we need.Protective grounding is the process of deliberate connection to the ground or its equivalents. Grounding is designed for insulated neutral mains, for instance, in old houses with 220/127 V mains.In some cases we use the neutral earthing technique; while in other cases we need protective grounding. This depends on the power supply system. Thus, mains with dead-earthed neutral point of the transformer's secondary winding require neutral earthing. The neutral earthing technique is used in all new residential houses and old houses where power supply systems were switched from 127 V to 220 V.