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HFCT pic

Current Transformer

The HFCT 100/50 is a high frequency transducer designed
specifically for picking up partial discharge signals.
It has a split core ferrite to allow retrospective fitting to earth
straps without the need for disconnection.
The durable body has a hinge and a quick release latch
making use quick and easy.
This transducer is ideal for all earth PD monitoring applications.
 
Capacitive Coupler pic
 Capacitively Coupled Sensors - Transient Earth Voltages

Partial discharge activity inside metal clad high voltage plant
induces small voltage impulses called Transient Earth Voltages
on the surface of the metal cladding.
These TEVs travel around the cladding surface to the outside
of the gear where they can be pick up using capacitively coupled
transducers.
Capacitive Coupler
The Capacitive Coupler detects TEVs as they pass over the
cladding of the high voltage plant. The very fast output signals
are recorded by the ASM.
 
Airborne Acoustic pic
 Airborne Acoustic Sensors - Surface Discharge
Corona in air and surface tracking can seriously damage high
voltage insulating surfaces in a way that will ultimately lead to
flashover and complete failure of the insulator.
This discharge activity creates acoustic emission that can be
detected using a high frequency sensor.
The magnitude of the acoustic emission is indicative of the
degree and severity of discharge activity.
Acoustic Probe
The acoustic probe is designed for use on air insulated terminations where there is a clear sound path between the electrically stressed insulation and the probe.
The sensor is extremely sensitive and can detect activity below 10pC.
The probe has a magnetic base to allow coupling to steel enclosures and a swivel head so the detecting sensor can be aimed directly at the HV point.
 
Airborne Acoustic pic
 Embedded Partial Discharge Sensors
High Frequency Current Transducers are used for the detection of
Partial Discharge (PD) in HV cables.
Coupled to the cable screen, they can detect PD in the cable insulation, cable joints or the cable termination.
Where the cable screen is terminated inside air insulated switchgear, individual HFCT sensors can be coupled to the screen from each core.
If sensors are installed at both ends of the cable, in the event of PD being detected, the sensors can be used to locate the source to within approximately ±1% of the cable length.
 
Weather Station pic
 Weather Station
Weather also affects cable operating conditions due to variations in cable soil (ambient) temperature, soil water levels and thermal conductivity and load.
Basic weather stations for outdoor use capable of monitoring rainfall, wind, temperature, humidity and pressure are commercially available.
These include data acquisition units with USB interface, so that the
data could be brought into the ASM monitor and inserted in the
database for later download.
 
Temperature and Humidity pic
 Temperature and Humidity
IPEC monitors are also fitted when requested with temperature
and humidity sensors to monitor the environment within the substation.
Humidity and temperature (owing to its relationship with humidity) are important factors in understanding the on-set and development of PD in switchgear, particularly surface discharge.
As switchgear PD monitoring is increasingly coming into focus, the
benefit of having environmental information is apparent.
The iSM web site has the facility for displaying this environmental data alongside PD data.
IPEC Ltd, Rutherford House, Manchester Science Park, Manchester, M15 6GG, United Kingdom.