Figure 6 High Frequency Current Transformers (HFCT)

Each sensor inductively measures the high frequency current signals within the PD pulses flowing in the earth or the conductor of the cable without the need for any direct, galvanic connection to the HV.

The sensors can be installed permanently during a planned outage or at the build stage of a project to enable On-line PD monitoring or routine spot testing.

On the other hand, a temporary installation of the HFCT sensors can be carried out if the cable earth is available outside of the termination box, enabling On-line PD spot testing without the need for permanent sensors or outage.

HFCT Sensor installation at crutch the of 3-core cable. Belted cables or with individually screened conductors with earth straps looped back through the HFCT.

HFCT sensors installation on single core cables. Earth strap looped back through HFCT. Mounted using silicone collars.

HFCT SENSOR RANGE:

High Voltage Coupling Capacitor (HVCC)

High Voltage Coupling Capacitor (HVCC) sensors are designed for permanent installation on MV/HV rotating machines to measure PD pulses occurring in the stator windings via a direct galvanic connection to the HV terminals.

Figure 7 High Voltage Coupling Capacitor (HVCC)

Once permanently installed, with the signal connections brought out to an external termination box, the sensor enables on-line PD monitoring and spot testing without the need for an outage. One coupling capacitor is installed on each phase of the machine for measurement of both phase-to-phase (end-winding) and phase–to-earth (slot section) discharges.

!5KV HVCC  sensors installation one sensor per phase in the motor terminal box.

7 KV HVCC sensors installation one sensor per phase in the motor terminal box.

All types of these sensors are compatible for use with the HVPD Kronos Permanent and HVPD Kronos Spot Tester.

HVCC sensor range

TRANSIENT EARTH VOLTAGE (TEV) SENSORS

TRANSIENT EARTH VOLTAGE (TEV) SENSORS are designed to detect local and high frequency PD pulses in switchgear, cable sealing ends, transformers and other plant. It is a compact, electromagnetic sensor capable of detecting high frequency radiation that is coupled onto an earthed metal surfaces from local PD within switchgear, bushings and other plant. TEV can be used to make on-line PD measurements in decibels (dB).

Figure 8 Transient Earth Voltage (TEV)

The TEV sensor can be magnetically attached or bolted to the outer surface of metal-clad switchgear typically on cable boxes or next to cable terminations. Also available is the outdoor type.

TEV sensor installed on switchgear Permanently installed to the inner surface of the switchgear housing using permanent clip.

TEV sensor attached to switchgear. Magnetically attached to the outside of the switchgear.

The TEV outdoor type fully weatherproof, installed on HV cable sheathing. Installed on the outer metalwork or earthed parts of the HV cable sheathing using a securing strap.

All types of these sensors are compatible for use with the HVPD Kronos Permanent and HVPD Kronos Spot Tester.

TEV sensor range

Airborne Acoustic (AA)

Airborne Acoustic (AA) ultrasonic sensor detects airborne acoustic signals from PD into air, including corona ( in outdoor substations ) and surface discharges and tracking ( in indoor air-insulated switchgear).

Figure 9 Airborne Acoustic (AA)

The AA sensor can be installed either inside or outside the switchgear panel, with clear line of sight to the PD source. It’s used in the HVPD’s MV AIS Switchgear Monitoring Solution in conjunction with the HVPD Kronos Monitor and Linearplex expansion module. When there a need for On-line PD monitoring of the MV AIS, the AA sensors are daisy-chained inside and along the AIS switchboard, typically with one sensor per switchgear panel.

Bushing Tap Sensor (BTS)

Bushing Tap Sensor (BTS) comes with a bespoke  Bushing Tap Adaptor (BTA) that detects PD signals from the transformer windings and the bushings, through the capacitance of the bushing.

Figure 10 Bushing Tap Sensor (BTS)

These sensors are installed permanently during a planned shutdown or at the build stage of a project to enable On-line PD monitoring or spot testing without the need for outages.

The BTS keeps the bushing tap grounded in the same way as the original tap cover, preventing any voltage rise on the bushing tap when in-service and is suitable for outdoor use.

The two pictures above shows the permanent installation of BTS on 275KV Transformers.

This sensor is compatible for use with the HVPD Kronos Permanent and HVPD Kronos Spot Tester.

BTA Range

Ultra High Frequency (UHF)Barrier Sensor is attached over the insulation barriers of Gas Insulated Switchgear (GIS).

Figure 11 Ultra High Frequency (UHF) Barrier Sensor

It can be connected to the UHF converter – an add on feature of the HVPD Kronos Spot Tester or used as part of HVPD’s GIS Monitoring Solution, enabling you to conduct UHF detection or permanently monitor for PD in HV/EHV GIS