Answer Posted / 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 .

what happened when we supply a dc current in dc motor?? can it worked properly?

1898

---

UG cable sizes were specified in sqmm. But practically its not coming to mesure. What's the reason for that? And how they specify the size of the cable?

1877

---

'documenˁ

1919

---

11kv/433v delta/star distribution transformer primary side full load Ht current is 83.33A in , but input side VCB rating 800A.why?

1610

---

Please nybody say, weather the result of Bharat Oman is declared or not? Probable date of declare???????

1951

---

I am having dual speed motor of cromton greaves make of 3.7 KW -1400 rpm and 5 KW - 900 rpm. Please let me know groups and winding connction for rewinding purpose.

1866

---

What is corkscrew rule?

1085

---

what is the breaking capacity and making capacity of circuit breaker and how

2067

---

What is the Surge for 1.1 Phase Induction Motor(For Eg.1Hp) 2.3 Phase Induction Motor(For Eg.1Hp) 3.AirConditioner(For Eg 1Ton) 4.Refrigerator(For Eg 180Ltr or 160kW) 5.Induction Cooker 4. Ceiling Fan

2005

---

Name two types of electrical analogous for mechanical system.

1154

---

1.what is mean by 8/20 micro sec waveshape

2169

---

What is shunt voltage and u v voltage witch one best

1668

---

how a resistor resists to flow the current?how an inductor oppses the sudden change in current?how a capacitor opposes a DC voltage.

2713

---

how much excitation voltage required to generate 1mw power?

1987

---

Could the power factor on electrical system can affect the registration of the kwhr meter or the CT/PT? 

1893

---