On-line Partial Discharge (OLPD) sensors

HVPD's range of OLPD sensors can detect dangerous partial discharge activity in cables (HFCT), rotating HV machines (HVCC or HFCT), switchgear (TEV or AA) and transformers (HFCT, TEV and Bushing Taps).
All HVPD's sensors are available in both portable and permanent versions, and supplied with complete installation kits. Permanent OLPD sensor installations are now becoming more popular in industries where plant outages are rare (the oil and gas industry, for example) to facilitate periodic OLPD diagnostic spot‑testing at any time, without the need for an outage. The installation, calibration and commissioning of sensor installations is always performed by HVPD's Installation Engineers.

High Frequency Current Transformer 

HFCT sensors are used to measure PD in HV cables, rotating machines (up to 20 MVA) and cable-fed transformers. We offer the widest range of HFCT sensors for OLPD measurement in the marketplace, including fully EMC-screened versions, outdoor weather protected versions, high‑current (1000 A) versions, and Ex/ATEX‑certified versions.

High Voltage Coupling Capacitor 

HVCC sensors are used to measure PD activity in the stator windings of HV generators and motors (from 3.3 kV to 30 kV). Our range of HVCC sensors have been tested to the voltage withstand and impulse levels as defined by the IEC and ANSI/IEEE standards. Ex/ATEX versions of HVCC sensors are also available

Transient Earth Voltage

The TEV probe is a high-frequency capacitive sensor that is used to detect local PD activity in metal‑clad MV switchgear. It is attached magnetically to the outside of the switchgear where it detects the transient earth voltages from the PD source. HVPD supply indoor and outdoor versions of the TEV sensor.

Airborne Acoustic

The ultrasonic airborne acoustic (AA) sensor detects airborne acoustic signals from PD into air, including corona and surface discharges and tracking. The AA sensor is used in the HVPD's MV Switchgear Monitoring Solution with the HVPD Kronos™ Monitor and Linearplex AA Sensor Expansion Module. 


The SMART-TB3™ is a world first, OLPD sensor for holistic plant condition monitoring of medium and high voltage (MV and HV) assets, including; rotating machines (direct or VSD-fed), switchgear and transformers.

Bushing Tap Adaptor Sensor 

The transformer bushing tap adaptor OLPD sensor can be used with portable OLPD test units and permanent OLPD monitoring systems to detect, measure and monitor partial discharge in HV/EHV transformers equipped with capacitive bushing taps.

Sensor Selection Guide

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Product HFCTHFCT_100_Thumb.png HVCCHVPD_Coupling_Capacitor_Thumb.png TEVHVPD_TEV_Thumb.png AALinearplex_Thumb.png SMART-TB3™HVPD_Smart-TB3_Thumb.png Bushing Tap AdaptorBushing_Tap_Adaptor_Thumb.png 
Power Cables            
Switchgear (MV) Air-insulated, Solid-insulated, Gas-insulated   Air-insulated, Solid-insulated, Gas-insulated Air-insulated    
Rotating Machines  Cable-fed, VSD Machines  Bus-fed, VSD Machines      Cable-fed, VSD Machines  
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Yes   No