The National Grid Demonstration is an extremely safe way to demonstrate the advantages of distributing power at high voltages.
The demonstration is made up of two step up/down transformers that are used to transform the 12V ac from a school power supply to 115V (nominal). The transmission line can be connected to either the low or High voltage connectors. The mounted bulb glows brightly when using the High Voltage connection and only dimly when the Low Voltage connection is used. Two sockets are provided to allow the high voltage to be measured safely using internal resistors to divide down the voltage to a safe level. The high voltage output is protected by an interlock that ensures that the high voltage is only enabled once the transmission line has been connected to the high voltage connector. Both ends of the transmission line are touch proof and use BS EN61010:2010 compliant connectors. Two pylons are also included to support the transmission line.
The National Grid Demonstration has been designed to prevent any access to hazardous voltages and is safe for students to use under supervision.
Using an a.c. Voltmeter and Ammeter, it is possible to make some quantitative measurements. With some simple measurements students can confirm that the low voltage and high voltage transmission line resistance is the same. Input power and output power can be measured and the power lost found for the low and high voltage connection.
The National Grid Demonstration comes with a detailed manual that includes step by step instructions and a discussion of other losses that that can occur in the system.