Tel: +44 (0) 1403 733782 
M +44 (0) 7834 530662 

Partial Discharge Analysis 

Independent services to determine the present condition and life expectancy of electrical power equipment by a combination of tests, inspections and documentary reviews. 
 
Pannell & Partners has extensive experience within the marine industry carrying out partial discharge and tan delta (dissipation factor) on HV assets including generators, motors and cables. 
 
Pannell & Partners is very proud to provide continual condition assessment of HV assets for Royal Navy and Royal Fleet Auxiliary platforms, with our engineers also providing support within the cruise line industry. 
 
Please see "Find out more" tab below. 
 

What is Partial Discharge Analysis? 

Partial discharge (PD) is an electrical discharge or spark that bridges a portion of the insulation between two conducting electrodes. 
 
Pannell & Partners’ engineers specialties and experience lie with rotating machine and 
electrical cable PD analysis and condition assessment for 3.3kV, 6.6kV, 11kV & 13.8kV 
applications. 
 
Our bespoke off-line test equipment has been designed and developed in a package 
ideally suited to marine applications as well as land based generation systems. 

Where does Partial Discharge occur? 

PD can occur at any location within the insulation system (between the two electrodes) where the electric field strength exceeds the breakdown strength of that portion of the insulating material. 
 
It can occur in voids within solid insulation, across the surface of insulating material due to contaminants or irregularities, within gas bubbles in liquid insulation or around an electrode in gas (corona activity). 
 
Partial discharge may occur in aged, defective or poor quality insulation and can propagate and develop until the insulation is unable to withstand the electrical stress leading to flashover and failure. 

How Pannell & Partners can help 

We provide Consultancy Services for electrical apparatus, including: 
 
Specialist in failure investigation of rotating electrical machines, root cause analysis 
Condition Assessment of MV and HV electrical plant (transformer, motors, generators, switchgear and cables) 
Breakdown visits and technical support 
Lifetime care and maintenance, annual inspection 
Power Quality Analysis (transients, harmonics, voltage dips) 
Preparation of rewind specification, witness factory acceptance tests, issue commissioning procedure and undertake on site commissioning/acceptance test followed by rewind. 
Off-line Partial Discharge Measurement: onsite (annual) maintenance and factory acceptance for new machine using in-house portable 11kV power source 
On-line Partial Discharge Measurement, remote monitoring, trending and diagnostics 
Our Engineers’ Experience with on-line & off-line Partial Discharge: 
 
Background in electrical rotating machine and electrical cable design, manufacturing, commissioning, repair & forensic analysis 
Power Plant, Cruise Ship and Warship maintenance & outage 
Specialised in failure investigation and condition assessment 
Over 15 years in offline & online PD measurement with many different analogue and digital PD monitors 
Testing and condition assessment for Cruise Industry, MoD, Petrochemical, Offshore & Utilities 
Consultation to clients facing PD issues including some major manufacturers of rotating machines 
Managing and supervising overseas rewind and repairs of many generators and Propulsion Motors on board cruise ships 
Wrote and maintain working documents for HV marine application management 
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