what is the safe meggar values for motor, transformer HT, LT
and Cables?
Answers were Sorted based on User's Feedback
Answer / ssreenu
megger value varies based on voltage of the system. If I
assume it is a 440 Volts system the megger value should be
min. 1 mega ohm.
Is This Answer Correct ? | 72 Yes | 29 No |
Answer / brajesh kumar singh
Megger Value (in Meg Ohms) = (system Voltage + 1)/ 1000
Is This Answer Correct ? | 29 Yes | 6 No |
Answer / akshay grover
Megger guys say, the value shall be
Megger Value (in Meg Ohms) = (system Voltage + 1)/ 1000
Is This Answer Correct ? | 30 Yes | 13 No |
Answer / imran
Magger value must be more than 2 mega ohm minimum..
Is This Answer Correct ? | 34 Yes | 19 No |
Answer / keith
If you need it to keep working, such as a sewage or storm
water pump,most reputable companys would trend the readings
beginning with the date the started servicing the motor and
watch for a dramatic decrease in test readings. One has to
be aware of the capacitance effect that water has on the
motor cable of a submersible pump as well as understanding
that it is normal to see a gradual decrease over a several
year period from above 200 megaohms @ 500 VOLT d.c. ( brand
new)to eventually down to 10 to 20 mega ohms. I have found
that although motors will run down to 2 mega ohms 230 volt
3 phase and 1 mega ohm to .6 mega ohms 480 3 phase they
don't run much longer. More important is to recognize
dratic decreases between monthly to quarterly readings as
they indicate potential failure ( direct short to ground)
which could trip main distribution breakers, thereby
effecting other motors or equipment by robbing them of
power. i.e. Alarm cicuits that are not battery back up
equipped.
Is This Answer Correct ? | 7 Yes | 0 No |
Answer / mohammad nazeer
system voltage in kv plus 1kv. if a motor system voltage is
480-v, its megger value should be 1.48megga ohm.
Is This Answer Correct ? | 7 Yes | 3 No |
Answer / dhamodaran.j
R>= (rated motor voltage/1000 +1)*10 (M ohm)
Is This Answer Correct ? | 3 Yes | 0 No |
Answer / v. srinivasa rao
It is depending on megger voltage if it is 1000 v megger the
equipment must be 100 M Ohm minimum value it is 5000 v ht
megger it must be 10 G Ohm minimum value.
Is This Answer Correct ? | 4 Yes | 2 No |
Answer / gins
More than 50mega ohms say that reference saramco check list
for megger test and for a hipot test this range will be more
than 100micro ampere.
Is This Answer Correct ? | 10 Yes | 9 No |
Answer / khan
there are some standard meggar values for transformers lt/ht
motors cable.
Is This Answer Correct ? | 3 Yes | 2 No |
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