Answer / ashish

We Can Not Define The Megger Value For HT & LT Cable Unless
& Untill We Don't Have The idea About How much KV Range
Megger We are Going Use As Megger Value is Also depends on
The KV Rating of megger....

Answer / chetan joshi

the formula to calculate magger value is < KV + 1 , where
kv is the voltage , suppose for 415 v system its value is
0.415+1=<1.5 m ohm

Answer / sharafuddeen

we are applying 1000v for LV cables and 2500-5000 volts for
MV cables.the megger value depends on the leakage current
during the injection of voltage.
so for minimum ,if we consider the allowable leakage
current as 100 micro amperes,the minmum insualtion
resistance for Lv cables is 10 mega ohms and and for mv
cables 25-50 mega ohms.
but normally the megger values are in the range of giga
ohms.
the formula KV+1 is not suitable for cables .it is suitable
mainly for the equipments like tranformers,motos...

Answer / pravesh

for ht lines megger value is .1000Mohm
for lt line megger value is 500 M ohm

Answer / kotha venkatesh

The formula to calculate meeger value is line voltage in
KV+1 if line voltage is 415volts then 0.415+1=1.415

Answer / naeem

Acceptable IR value for HT cable with Megger at 5KV is 1000Mohm and for LT cable with Megger at 500V is 2Mohm and If the obtained value is less than these then cable may be suspected, we can energise the cable even with low values and it will stand but with full load in high temperature any time cable can create problem , so the standard is 1000Mohm for HT and 2Mohm for LT cable.

Answer / devendra kanderi

HT cable magger value shuld be 500 mega ohm minimum and LT cable magger value shuld be 100 mega ohm minimum.

Answer / guru

if 120 kw above ht and below is lt

Answer / kota venkata rao

I coincide with the opinion that the thumb rule of KV+1 for
is not suitable for cables . For cables there shall be a
minimum value which shall be more than the value derived as
per the kv+1.The IR value varies with the operating
temperature. The value shall be high at at ambient
temperature and low at higher temperatures. However megaar
instrument 1 kv upto 1 kv rating and 2.5 kv to 5 kv upto
and including 33 kv

Answer / k.prakashchandra

Roughly,megger values should be 2 Meg-ohms for every KV
rating at 60' C for 11KV and above.The value doubles itself
for every 10' C fall in temp.For LT 500v/1000v megger is
used ,and IR value should be more than 1 M-ohms.For HT 5 KV
megger is used.PI value can also be measured with the
motorised megger.Comparing the values obtained with the
previously obtained for any fall is important

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