what is the difference between megger and hipot

[ian23jess]

para po sa mga experts dyan. wala po ako masyadong alam sa electrical, ano po ba ang pagkakaiba ng dalawa? megger and HI-pot since na parehas naman sila nag titest ng insulation.. kasi po dito sa saudi sa pinagtatrabahuan ko ang tawag nila sa insulation test is megger samantalang sa dati kung company sa pinas which is manufacturing actually, is hipot. thanks in advance po sa mga sasagot

[zer0w1ng]

Megger is a ohmeter in megaohm range while hipot is to test insulation.
Megger can measure also insulation but not test the actual breakdown voltage.
Both uses high voltages.  Megger uses DC while hipot use short pulses.
Megger reading is in ohms, while hipot is in kiloVolts.

[KANGARO]

para po sa mga experts dyan. wala po ako masyadong alam sa electrical, ano po ba ang pagkakaiba ng dalawa? megger and HI-pot since na parehas naman sila nag titest ng insulation.. kasi po dito sa saudi sa pinagtatrabahuan ko ang tawag nila sa insulation test is megger samantalang sa dati kung company sa pinas which is manufacturing actually, is hipot. thanks in advance po sa mga sasagot

mayron na yata nag post d2 sis,,,try pakecheck.....e2 sa ibang forum

Hi-Pot is a generic term for High Potential Test. Megger is a brand which has become a generic term for a similar testing device for lower voltage equipment. In different applications, "high potential" has vastly different meanings. In integrated electronics, high potential may be 150 volts, whereas in the power industry, high potential is in the 15000 volts range and above.

Both hi-pots and meggers can be used for testing insulation resistance. However, testing only resistance does not give a complete picture of the health of the insulation. Meggers usually apply 600 to 2000 v for 1 minute or less, for a "snapshot" of the insulation at existing ambient conditions. Motor, generator and transformer windings, as well as medium and high voltage power cables. When testing Hi-Voltage cable, the high potential is gradually applied over a period of about 15 minutes minutes, with readings taken at the 1 minute intervals. The reading are the cable leakage current in micro-amps. The maximum applied test voltage is 300 volts per mil of insulation. A 15 kv cable with 175 mils would be tested at about 50000 volts. As the voltage is applied, the tester notes the leakage current at the end of each minute interval. As long as the leakage current remains constant or decreases, the cable is considered satisfactory.

Hi-pots are also useful for locating damage in faulted underground cables, a process called "thumping". The cable is disconnected at both ends, and the hi-pot is connected between the conductor and ground. A closed spark gap is attached in parallel with the hi-pot. As the spark gap is widened, the voltage output of the hi-pot will rise further each time before the spark to ground collapses the voltage. At some point, the spark gap becomes a higher impedance path to ground than the cable fault. The sparks no longer jump the gap. The sparking now occurs at the location of the fault. The cable arcs create a fairly loud sound and the location can usually be found readily with a ground microphone and headset.

[piona]

^^add ko lang....Megger is an equipment brand that specializes insulation testing back in 80's, sila ang sikat pagdating sa insulation tester, kaya naging tawag sa insulation testing ay megger, pero brand talaga yan ng tester. Kagaya ng toothpaste na tinatawag natin noon na colgate  

Yong hi-pot naman ay short-cut for high-potential (high-voltage) insulation testing.

Sa ngayon malabo ng tawaging megger ang insulation testing dahil marami ng produkto ang Megger as a company  
  

[ian23jess]

ang sarap talaga maging member ng site na it!...he he bale ano po mas useful gamitin na pang test sa dalawa kung ang mga wires eh may moist dahilan para ang ckt breakers ay mag trip?

[piona]

Pareho lang po ang ibig sabihin ng dalawang tester na yan Megger at Hi-Pot, pareho po silang "insulation tester" using hi-voltage para makuha accurately ang high insulation resistance in terms of 1M-10T.

Depende lang po yata sa voltage rating ng wire na titestingan, kung hi-voltage cable (kv) ito,  pwede gamitin either sa dalawa. Ang importante lang ay makuha accurately ang insulation level ng wire.

[piona]

...naalaala ko ngayon, yong hi-pot ay brand name rin ng isang "insulation tester"! Hipotronics po nga pala ang company nila in short hi-pot hehehehe.....

ito website nila : http://www.hipotronics.com/

ito naman ang sa megger usa:  http://www.megger.com/us/index.php

[dan.enriquez]

^^ ayos parihong tama yung mga sinabi ni sir zer0w1ng, sir CORE at DUKE SSHREKK.. one time lang ako nakasubok na mag calibrate ng HI-POT, pero yung MEGGER palagian na akong nakakapagkalibrate nyan dun sa dati kong pinapasukang kompanya.

[ian23jess]

ah ganun pala maraming salamat po sa inyo nalinawan na ako... pogi points po sa inyo

[tony]

para po sa mga experts dyan. wala po ako masyadong alam sa electrical, ano po ba ang pagkakaiba ng dalawa megger and HI-pot since na parehas naman sila nag titest ng insulation.. kasi po dito sa saudi sa pinagtatrabahuan ko ang tawag nila sa insulation test is megger samantalang sa dati kung company sa pinas which is manufacturing actually, is hipot. thanks in advance po sa mga sasagot

pahabol.......

in my job as a QAQC inspector in oil and gas refinery construction projects, we do these hi-pot and megger testing of cables, hv motors and generators...

meggering is to find out the insulation resistance value of cable insulations....a dc voltage is impressed on the cable, dc voltages are 500v for motors, 1kv for low voltage cables, 5kv for high voltage cables.....

low voltage cables does not require special termination kits unlike high voltage cables......so meggering is enough to stablish cable integrity.....

testing is carried our for a duration of 1 minute and readouts are in meggeohms or gigaohhms depending on the test equipment used....we used Fluke 1587 megger, and the BM21 megger which is capable of 5kv test voltage...

In Russia, testing is allowed only when ambient temperature is not lower than -5 degrees Celsius....or when the client allows it...


high voltage cables are terminated using termination kits such as "raychem", to be allowed to perform high voltage cable terminations, you have to have a license....when such terminations have been completed on a hgh voltage cable, there is a need to show the "client" that cable preparation(termination) have been done correctly and that cable integrity was maintained, hig pot testing is carried out.

Now hi-pot testing can either be dc or ac.....in our case whe use dc and test voltages can be anywhere from 10kV to 45kV depending on the type of cable being tested or by cable vendor recomendations....of course in our case we follow Russian Federation Standards....

The thing about Hi-pot is that the leakage current should be low at all times and not increasing with time....testing is carried out anywhere between 3 to 5 minutes....and is always witnessed by the client...

when doing hi-pot, the read-out is leakage current in micro-amperes over a given period of time....it should never go up but should go down instead....

voltages are also ramped-up in stages...the reason for this is that cables have initial charge of 0volts and has a finite capacitance, therfore a transient starting cirrent can be significant that it can trip our equipment...

after the testing period has been reached....voltage is ramped down slowly to conclude the hi-pot....cables are discharged using a shorting stick....

meggering is again done as a matter of procedure...it is interesting to know that the meggering results before and after hi-pot are never the same....

[zer0w1ng]

Very good insight sir.
Thanks for the info.
+1

[tony]

thanks zerowing, actual experience yan......i have done lots of cable meggering and hi-pot testing in my 15 years working in oil and gas industry....

[tony]

one time lang ako nakasubok na mag calibrate ng HI-POT, pero yung MEGGER palagian na akong nakakapagkalibrate nyan dun sa dati kong pinapasukang kompanya.

lahat ng measuring equipment namin, merong 1 year validity ang calibration, so once a year pinapadala namin yung mga iyon sa "metrology center" para maverify ang calibration....kung successfull, papalitan ang calibration stickers, at sinasamahan ng calibration certificates para me traceablity...

yung clients namin, any time nag che check sila nyan, kadalasan nanghihingi nga copies ng certificates....

lahat ng testing na ginagawa namin, meorng documentation, "protocols" ang tawag nila dito sa Russia....QCR's naman ang pinapadala namin sa client after na magperform kami ng testing...

[jacks]

+1

Para sa info. Simple at galing sa experience.