PD-4 is for PD measurement and analysis, as well as for effective defect location in high voltage equipment insulation. The device is most effective for PD measurement in:

Power transformers
Instrument voltage transformers and current transformers
Switch-gears and Gas-Insulated switchgears
Cables and joints
Post insulators and overhead line insulator

PD-4 has one UHF measuring channel. Using rod or directional antenna with the device, you can distantly measure the PD impulses from 200 to 1500 MHz. The PD measurement in UHF frequency range allows to get rid of corona discharge influence, which is very intensive at high voltage substations, especially of the open type.

This is because the corona pulses are of low frequency, usually less than 100 MHz, so they are not measured. The PD electromagnetic radiation in HV equipment insulation can be measured by PD-4 with the antennas of two types:

• UHF Rod Antenna, equally sensitive in all the dire

In this case the defect location is done by comparing the HV radiation intensity from different parts of the substation: usually the equipment with the insulation defect, which causes the PD pulses, is situated in the zone of the most intensive radiation.

• UHF Directional Antenna, which has the maximum sensitivity in its longitudinal axes direction.   

In this case the location of the defect zone (the zone with the most intensive electromagnetic radiation) is done by the antenna turning, which is rather convenient in practice.

Expert evaluation of measurements

PD-4 allows not only to reveal a defect, but to specify its type and place. For that it is necessary to synchronize the measurement process with the power supply phase. For that the «PFR-1» device, which passes the synchronizing pulse to the KD-4 by the radio channel, is the most suitable. It is important that during the PD measurement synchronizing to the power supply phase it is possible to view the library of the standard insulation defect images.

PD-4 is supplied with the «PD-Expert» diagnostic system for the defect type specifying. The «PD-Expert» system compares the «PRPD» and

«PD-Cloud» of the measured PD pulses to the images stored in the standard defect database of the «PD-Expert» system.

PD-4 is used for :

Periodic insulation monitoring. In this case general PD measurement is done with the device
Deeper insulation condition monitoring with additional functions and the expert system

Expert system can determine the type of defect in the insulation.

Channels	3
Acoustic frequency range	30~300 KHz
HF range	0.5-30MHz
UHF range	200~1,500MHz
Display resolution	640 * 480
Measurement range	10~100,000pC
Interface to PC	USB
Battery life	10 hrs
Operation temperature	-20 ~ 40° C
Dimension	220 * 170 * 35
Device weight	1kg
Weight (including accessories)	12 kg