Online Partial Discharge Monitoring for Rotating Machine

Online Partial Discharge Monitoring for Rotating Machine

Sparks Instruments SA, MC-monitoring SA , Switzerland

Advance notice the conditions of your generator or large motor's insulation for very effective preventive maintenance. Much reduce unplanned shutdown.

The system will get online the high frequency signal from the high voltage power of the generator or large motor and this high frequency signal can be the indicator for partial discharge level in each certain part of the generator or motor. At a certain level of partial discharge that we get online from the system can be used to plan the inspection or overhaul the generator or the large motor. it is for Hydro Generators, Turbo Generator, Wind turbine, industrial Motors.


typical Installation Partial Discharge Online

Local Data Visualization

The system comprises of 1000pF high voltage Coupling Capacitor to get all the target frequency from the high voltage level and the signal is fed into the Partial Discharge Online Monitoring unit. The unit will show the instant Partial Discharge information. it also record the information and create a trend for projection. The information can be viewed from the LCD screen of the unit or can be download to a notebook PC. in addition the information can be conneccted online to the data storage server for later analyse. The information can also be communicated via SCADA. Many units of Generators and/or Motors can be monitored separately and send all the information to the data storage server.

Coupling Capacitor 24kV rms 1000pF for online partial discharge monitoring

Coupling Capacitor 24kV 1000pf Key Features

-Norminal voltage 24kV rms

-Build in Quadrupole with voltage

reference output

-Build in Overvoltage Protection

-Capacitive floating Signal output

to avoid Eddy Current Loops

Coupling Capacitor

















There is a case that the Coupling Capacitor cannot be used as their electrical connection point is close to the surge absorbing capacitor of the generator, then the high frrequency current transformer (HFCT) shall be used. The system connection is the same as the coupling capacitor.

High frequency current transformerSurge Capacitor with HFCT

The online partial discharge monitoring unit can be a portable one or a permanent installation in a junction box nearby the coupling capacitor

portable Partial Discharge Analyser

System Connection PD Online

 Sparks Instruments offers the unique 3 phase simultaneous measurement of the partial discharge online monitoring that can monitor the end winding section of the generator. this system mesure partial discharge signal between phase to phase not only phase to ground. the extended local display is below;

Local Data Visualization Extended phase to phase

in addition, Sparks Instruments offers the various effective noise rejection method so that the partial discharge pattern cen be viewed clearly without noise from the system

Noise Rejection with Filtering

Noise Rejectionwith Gating

Many Generators or Motors' partial data can be fed into the central station for comparison and stored for analyse. the system can be communicated to SCADA.

system Intregration with SCADA



This Partial Discharge Online motoring system will supervise the insulation of the winding of the generator and/or large motors. There is another effective and benefitial tool to indicate in advance the rotor interturn short circuit using what we call Air Gap Flux Probe.

Apart from this Partial Discharge Online monitoring system for Generators and Large Motor (rotating machines) , Sparks Instruments also offer the instulation and condition monitoring system for large transformer, high voltage gas insulated switchgear, underground installation high voltage cable, high gas insulated busduct and also medium voltage switchgear.


The other part that we would like to introduced together with the above monitoring is the Airgap Flux probe for early detection of short circuit in the inter-tuen of the rotor in the generator and also Insulation and condition monitoring for high voltage equipments. Pls click,


For Thai, link below provides some more information on Partial Discharge.

Basic information in Thai.

Application insulation monitoring machine