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5 THEORY OF OPERATION
5.1 General Operation
The purpose of the PIU is to identify the connected electrical phase of a residential or
commercial property without entering the property or connecting equipment to the property.
Equally, there is no requirement to install any equipment within the local substation.
Figure 4 below, shows the context in which the PIU is used and the various data connectivity the
unit uses to achieve this identification.
PHASE IDENTIFICATION UNIT
REMOTE REFERENCE UNIT
RESIDENTIAL OR
COMMERCIAL
PROPERTY
RADIATED
ELECTRIC AND
MAGNETIC FIELDS
MAINS SUPPLY
SATELLITE
COMMUNICATIONS
SATELLITE
COMMUNICATIONS
MOBILE COMMUNICATIONS
Figure 4 - Theory of Operation – PIU Context
The PIU is able to measure the instantaneous phase of the electrical field being radiated by any
property. The original source of this radiation does not have to be the properties internal
electricity meter, but can be any live cable, including the electrical connection to internal lights,
sockets and any external lights.
The PIU is then time synchronised with a remote reference unit that is also measuring the
instantaneous phase of the mains supply connected to it. The remote reference unit then
communicates this phase measurement (along with other data, such as GPS time), to the PIU
using the integral mobile communications link.
The time synchronisation between the PIU and the Remoter Reference Unit is achieved through
the 1-second timing provided by the GPS Satellites. This is a very accurate timing reference
source.
With the two units in synchronisation and communicating, the PIU compares both sets of data
and is able to determine and display the properties connected phase, within 10 seconds.