hiam in the process of purchasing a flat.under the electrical specifications, the builder has specifid the following. please explain me what does it mean by3 phase power supply with automatic change over switch and what does it mean by RMU Transformer with Advanced Features
This electrical specification describes some aspects of the electrical distribution system for a block of flats (apartment building in USA terms). A 3 phase power supply is 3 live wires and a neutral with 400 volts or so between any two live wires and 230 volts or so between any live wire and the neutral. Each flat would be connected to one live wire and neutral. A change over switch is a switch that can switch the load from one power source to another. It could switch between two mains connections from the power company or it could switch between the power company mains and a standby diesel generator set. An RMU transformer is a ring main unit transformer. The transformer would be the step down or substation transformer from the transmission line voltage to the 400 volt level. There would probably be one transformer for all of the flats, possibly two if there are two mains connections from the power company. The RMU designation indicates that the transformer includes additional components such as the change over switch and main circuit breaker as a single piece of equipment. Advanced features might include such things as transformer temperature monitoring, load monitoring, and remote indication provisions. Unless the features are enumerated, it isn't a particularly useful description. It may or may not include features in addition to the minimum required by government regulations. If you are purchasing only an individual flat, this might offer some assurance that the electrical system is modern and reliable, but it is a very poor description to offer prospective purchasers of individual flats.
