Frequently Asked Questions (FAQs)

When do we conduct 24 hours monitoring for a period of 5 days or more?2018-07-27T16:43:34+08:00

24 hours monitoring and beyond is usually carried out when there is a high amount of disturbances esp harmonics and from the surrounding. Such disturbances can interfere with our noise filtering software and the partial discharge analysis.Another reason is when there is a presence of cavity or insulation discharges in the equipment. This needs to be captured to track when the discharge activity is the highest in order to accord the proper severity levels for later follow up if necessary.Therefore, in such cases, online monitoring of 24 hours or beyond is preferred.We will recommended 5 days or more depending on the kind of data to be collected and the plant’s operational requirements.

Can we conduct 24 hours monitoring for a period of 5 days or more for GIS systems?2018-07-27T16:44:18+08:00

Yes. We are capable of 24 hours and beyond monitoring on most types of High Voltage Equipments.

Can we choose to skip the 24 hours or more days monitoring and do snapshot instead?2018-07-27T16:46:14+08:00

It is better not to if the conditions mentioned above is evident as problems missed could be catastrophic at a later date and when such conditions can created a significant change in the PD activity esp in the presence of cavity or insulation discharges. We based our recommendations on our expertise and experience so that unforeseen accidents or occurrence can be minimized as much as possible. However it is not a mandatory test.

What kind of result can I expect from 24 hours and beyond for monitoring?2018-07-27T16:47:47+08:00

The focus of the report will be to inform on the severity of the equipment condition inspected using our severity table. Should there be abnormalities detected, our suggestions and recommendations will follow. The format of the report will be similar to that using snap shot testing, however the data collected for our analysis will be much more with charts showing the trend of Partial Discharge activity over the period of monitoring.

Is partial discharge online monitoring carried out live on High Voltage equipment and do you need to open the panel covers?2018-07-27T16:48:13+08:00

Partial Discharge online monitoring is carried out live on High Voltage equipment without having to opening the covers.It is very safe Being an Airborne System, measurements can still be taken with or without the covers at a safe distance.

How many equipment can be monitored at any one time?2018-07-27T16:48:44+08:00

It depends on the condition of the equipment after an initial inspection using snapshot.Usually it would fall between 2-4 panels for a 20 panel switchboard or some panels and transformers at the same time if a 16 channel PD Fibre online monitoring system is used.

What is the time interval between each data collection?2018-07-27T16:49:08+08:00

Usually 1 hour.

Will online monitoring cause any disruption to the operation?2018-07-27T16:49:32+08:00

No, as no emission of any kind is generated during the entire monitoring period.

Is noise a problem when measuring Partial Discharge?2018-07-27T16:49:53+08:00

Yes, it is a problem especially when it is an airborne system. However with extensive site experience built up over the years, we have developed powerful softwares with unique algorthms to eliminate most of the broadband noise picked up during inspections.

What are the equipment that can be tested with the PD PAC Partial Discharge ?2018-07-27T16:50:19+08:00

Most High Voltage equipment from 3KV and above can be tested, of types such as GIS, Vacuum or oil breakers, motor, transformer and tap changers etc.Depending on the design of the electrical equipment and the strength of the electric field,even low voltage equipment can generate Partial Discharges such as LV busbars,LV motors etc.Also, the higher the voltage the higher is the likelihood of occurrence of Partial Discharge.

Is it important to identify the type of discharge?2018-07-27T16:51:25+08:00

Yes, it is important as insulation problems can be serious leading to flashovers if it is not detected early. Also, insulation problems cannot be easily seen until it is too late.

Do you need to monitor for more than 2 days any high voltage equipment suspected of having partial discharge activity?2018-07-27T16:51:51+08:00

Contrary to popular beliefs, Partial Discharge is present in all High Voltage equipment in small quantities and low magnitudes. It is when problems start to develop that the partial discharge activity increases. With a highly sensitive sensor, you can detect the increased in partial discharge activity almost instantly. From our wide experience,only 2% of the equipment inspected would require 2 days or more in on-line monitoring to capture PD information accurately.There is no need for a shut down in doing this test.

Should Partial Discharge Testing be done before or after a service shutdown?2018-07-27T16:52:10+08:00

Partial Discharge Test should preferrably be carried out before a service shutdown of the High Voltage equipment so that problems found are rectified thoroughly when the equipment is denergised.Better still is that root cause analysis can be carried out when the equipment is still intact.

How is the PD PAC compares with the rest of the partial discharge testing systems in the market?2018-07-27T16:52:31+08:00

One big advantage of the PD PAC is its portability and it does not required any power supply at site to operate making it easier to move around.Also,it is versatile and does not require many sensors to test for different equipment or applications.If short term monitoring is required,the same system can be deployed for this purpose without incurring additional cost for the customers.In addition,the softwares are specially developed to detect and identify Partial Discharges based on empirical data collected from true case studies of actual problems found at sites over the years.

Is partial discharge carried our on live High Voltage equipment and do you need to open the panel covers?2018-07-27T16:52:55+08:00

Partial Discharge is carried out live on High Voltage equipment without having to opening the covers. Being an Airborne System, measurements can still be taken with or without the covers.

If Partial Discharge testing is so good and highly rated, why is it not many people are adopting this testing method?2018-07-27T16:54:24+08:00

There are three reasons behind this:

  • PD testing is a fairly new technology compared to the usual Hipot (Megger) test. PD testing has matured over the years and today it has already been proven to be much more powerful indicator for insulation defects compared to offline test (like hipot, Megger etc).
  • PD testing may be the most powerful indicator for detecting insulation defect but it is also the most sophisticated test to be carried out. The interpretations of the results are extremely challenging and require very well trained personnel to do the analysis. Once results are correctly interpreted, PD testing will give the best detailed diagnosis of the insulation condition of equipment compared to any Hipot. Megger test etc.
  • As PD testing is sophisticated, the cost of inspection is generally much higher than usual Hipot testing. However, the cost of PD testing is much lower nowadays.
Is Partial Discharge (PD) accurate? What standard does it conforms to?2018-07-27T16:54:52+08:00

PD Testing is an internationally recognized testing technique used in more than 28 countries for detecting insulation defects. According to IEEE 400, the only proven and effective way to establish an electrical preventative/ predictive maintenance program is using Partial Discharge Testing.
Many grids are turning to this test as a first line test to check for early insulation defects as it is totally non destructive in nature compared to the usual hipot test.

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