Installation
An ac or dc supply is required by the SCM and the output signal (nominal 63.5Vac) is wired to the location of the measurement equipment which is normally in the protection or metering room.
Sample wiring drawings are available in the Downloads section of this website.
Field Experience
The product has many years of field experience at voltages from 115kV to 400kV - the PQSensor™ is applicable at any voltage where CVTs are installed. PQSensor’s™ have been field retrofitted to a variety of different designs of CVT and have also been supplied ‘factory fitted’ by all of the major manufacturers of CVTs. Applications have included power quality recording, fault and disturbance recording and monitoring of high speed transients on transmission systems. The PQSensor™ has been used to accurately measure power quality parameters such as harmonics and flicker over a wide bandwidth from subsynchronous harmonics to high frequencies.
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General Description
The PQSensor™ is a factory or field installable transducer that equips a CVT with an output signal that faithfully reproduces the harmonic spectrum of the primary h.v. input. This output enables CVTs be used with any power quality monitoring device to accurately record power system harmonics and transients. The installation of the PQSensor™ on a CVT does not in any way affect the normal operation of the CVT.
Introduction
To make accurate measurements of harmonics and other power quality phenomena in a transmission substation the number one requirement is to have access to a voltage signal that faithfully reflects the full harmonic spectrum of the primary system voltage. The three most common sources of voltage signals in a transmission substation are listed in the table below and the benefits and limitations of each is considered.
It is evident from this summary that none of the above sources meet the requirement of providing a readily available voltage signal suitable for accurate harmonic measurement in a cost effective manner.
The PQSensor™ is a transducer that can be fitted to an existing in service CVT, or supplied factory fitted with new CVTs and provides an output signal that meets this requirement.