Answer / erharisheee51

i Guess Megger test means Insulation Resistance test ..using
Megger test itself we can able to find the insulation
strength interms of resistance only ..
so what is that question ? please be clear that resistance
and megger test are similar ..

and remaining inductance test i don't know that ..

is it correct , Please clarify

Answer / ramesh

Insulation test for checking of winding healthy condition,
If any short circuit inside area, the motor cannot operate.
So that before energised motor, insulation test to be done.

Answer / stan grzegorski

Megger (or Insulation) test will test ISULATION ONLY . A "
Megger" is one manufacturer of insulation testers . This (&
most other) insulation tester also has a low resistance
range for measuring & COMPARING motot winding
resistance .Insulation resistance is normally measured at
twice the RMS line voltage minimum , (For 240 Volt rated
equipment the 500V setting is used )DO NOT USE IT IF THERE
ARE SESITIVE ELECTRONIC COMPONENTS IN CIRCUIT . ( You WILL
destroy them ). BE VERY AWARE !! The 500 V & 1000V settings
on these instruments is not what they are measuring ,IT'S
WHAT THEY ARE SUPPLYING , & IF YOU ARE PART OF THE CIRCUIT
THAT IS WHAT YOU WILL BE SUPPLIED WITH !The output current
is limited to a safe level , but if there are any
capacitors in the circuit , THIS CAN BE MULTIPLIED MANY
TIMES to a dangerous level.Specifications for insulation
resistance to earth ( Ground /Chassis ), is 1 M ohm ( 1 Meg
ohm , 1,000,000 ohm ), but in reality if isulation
resistance is 10 Mohm or under , the equipment may need
drying out , or is on its way to the bin . The low
resitance range is for measuring continuity , in this case
that the motor windings aren't broken , normally in the
order of a few ohms , & on larger motors less than 0.5
ohms .Inductance is an electromagnetic parameter which
affects AC or varying DC current & is dependent on the
frequency of the AC current or the RATE OF CHANGE of DC
current . ( Higher frequency = Higher inductance ) > In
most AC machines (Motors , transformers etc.)the Inductive
reactance is cosiderably larger than the resistance , &
measuring inductance can identify faults which would be
practically impossible using resistance measurements .

Answer / amit

My senior while
checkin ht
motor ,first he
measured
resistance using
micro ohmmeter
and he got 25m
ohms after tat he
meggered it
getting 5Gohms...
So i asked this
question...

WHY HOLDING CONTACTOR OF MOTOR STARTER IS CALLED NO VOLT COIL.

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