Meter for measuring accumulated power consumption of an electrical appliance during operation of the appliance

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS With reference to FIGS.
1A to 1D, reference numeral 10 generally indicates a power meter comprising a body member 12 provided with prongs 14 on its rear side for insertion into an electric wall socket (not shown).
An electric socket 16 is provided on the top of the body member for receiving the electric plug of an electrical appliance (not shown).
The power meter 10 is further provided with two displays on the front of the body member 12.
The first display 18 indicates cumulative electric power consumption and the second display 20 indicates the time period over which the electric power has been consumed.
The power meter 10 further includes a power bar 22 which comprises a row of five LED's.
The two LED's on the right hand side, indicated by reference numeral 22.
1 are red, the two LED's 22.
2 on the left hand side are green, and the LED 22.
3 in the centre, is white.
The purpose of the power bar 22 is to indicate when a high or a low power consumption device is connected, by either lighting up the red or the green LED's.
In an intermediate condition, the central white LED is lit up.
The power bar 22 therefore gives a qualitative indication of power consumption.
Thus, when very high power consumption appliances are connected, the rightmost red LED 22.
2 will be lit up and in less severe conditions, the next LED 22.
2 will be lit up.
On the other extreme, when very light power consumption appliances are connected, the leftmost LED 22.
1 will be lit up and then the next LED 22.
1, as the case may be.
Alternatively, the operation of the power bar 22 may be cumulative, e.
g.
if an electrical device is of intermediate power usage, both the green LED's 22.
2 and the white LED 22.
3 may light up.
The working of the power meter 10 will now be described with reference to FIG.
2.
To determine the amount of power consumed by an appliance, the power meter 10 makes use of the fact that an alternating current in a wire generates a proportional magnetic field, and vice versa