24-12-2014, 06:11 PM
pl. explain the
megar working principle
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whai is working principle of megger pdf
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pl. explain the
megar working principle
10-04-2017, 11:50 AM
The quality of the insulation resistance of an electrical system is degraded over time, the condition of the environment, ie temperature, humidity, moisture and dust particles. It is also negatively impacted by the presence of electrical and mechanical voltage, so it is very necessary to check the insulation resistance of the equipment at a constant constant interval to avoid any death or electric shock.
Construction of Megger
Characteristics of the circuit construction: -
![[Image: megger-principle1.gif]](http://www.electrical4u.com/images/megger-principle1.gif)
1) Deflector and control coil: connected in parallel to the generator, mounted at right angles to each other and maintaining the polarities in such a way as to produce torque in the opposite direction.
2) Permanent Magnets: Produces the magnetic field to divert the pointer with the magnet of the North-South pole.
3) Pointer: One end of the pointer connected to the coil of another end is diverted on the scale from infinity to zero.
4) Scale: A scale is provided on the front of the megger from the range 'zero' to 'infinity', allows us to read the value.
5) D.C generator or battery connection: The test voltage is produced with manually operated manual generator for manual Megger. Electronic Voltage Battery / Charger for Megger automatic type for the same purpose.
6) Coil Resistance of Coil and Current Coil Resistance: Protect the instrument from any damage due to low external electrical resistance under test.
Megger Operating Principle
• Voltage for test produced by manual crank rotation megger in case of manually operated type, a battery is used for electronic tester.
• 500 Volts DC is sufficient to perform tests in the range of equipment up to 440 Volts.
• 1000V to 5000V is used for testing high voltage electrical systems.
• Coil of deflection or coil of current connected in series and allows to flow the electric current taken by the circuit that is being tested.
• The control coil also known as the pressure coil is connected through the circuit.
• Current limiting resistor (CCR and PCR) connected in series with the control and deflection coil to protect against damage in case of very low resistance in the external circuit.
• In the electromagnetic induction effect of hand-operated megger is used to produce the test voltage, ie the armature is arranged to move in permanent magnetic field or vice versa.
• Where as in electronic type megger batteries are used to produce test voltage.
• As the voltage in the external circuit increases, the pointer deflection increases and the pointer deflection decreases with increasing current.
• Therefore, the resulting torque is directly proportional to the voltage and inversely proportional to the current.
• When the electrical circuit being tested is open, the torque due to the voltage coil will be maximum and the pointer shows "infinity" means that there is no short circuit across the circuit and has maximum resistance inside the circuit under test.
• If there is a short-circuit pointer that shows 'zero', which means that 'NO' resistance inside the circuit is being tested.
Philosophy of work based on ohm-meter or ratio-meter. The deflection torque is produced with the mega meter because of the magnetic field produced by the voltage and current, similarly to 'Ohm's Law'
The megger pair varies in the ration with V / I, (Ohm's law: -V = IR or R = V / I). The electrical resistance to be measured is connected through the generator and in series with the baffle coil.
The torque produced will be in the opposite direction if the current supplied to the coil.
1. High resistance = No current: - No current will flow through the deflection coil, if the resistance is very high, ie the infinity position of the pointer
2. Small resistance = High current: - If the circuit measures a small resistance, it allows a highelectric current to pass through the deflection coil, ie the torque produced make the pointer to set to 'ZERO'.
3. Intermediate resistance = varied current: - If the measured resistance is intermediate, produce the aligned pair or adjust the pointer between the range of 'ZERO to INIFINITY'
Construction of Megger
Characteristics of the circuit construction: -
1) Deflector and control coil: connected in parallel to the generator, mounted at right angles to each other and maintaining the polarities in such a way as to produce torque in the opposite direction.
2) Permanent Magnets: Produces the magnetic field to divert the pointer with the magnet of the North-South pole.
3) Pointer: One end of the pointer connected to the coil of another end is diverted on the scale from infinity to zero.
4) Scale: A scale is provided on the front of the megger from the range 'zero' to 'infinity', allows us to read the value.
5) D.C generator or battery connection: The test voltage is produced with manually operated manual generator for manual Megger. Electronic Voltage Battery / Charger for Megger automatic type for the same purpose.
6) Coil Resistance of Coil and Current Coil Resistance: Protect the instrument from any damage due to low external electrical resistance under test.
Megger Operating Principle
• Voltage for test produced by manual crank rotation megger in case of manually operated type, a battery is used for electronic tester.
• 500 Volts DC is sufficient to perform tests in the range of equipment up to 440 Volts.
• 1000V to 5000V is used for testing high voltage electrical systems.
• Coil of deflection or coil of current connected in series and allows to flow the electric current taken by the circuit that is being tested.
• The control coil also known as the pressure coil is connected through the circuit.
• Current limiting resistor (CCR and PCR) connected in series with the control and deflection coil to protect against damage in case of very low resistance in the external circuit.
• In the electromagnetic induction effect of hand-operated megger is used to produce the test voltage, ie the armature is arranged to move in permanent magnetic field or vice versa.
• Where as in electronic type megger batteries are used to produce test voltage.
• As the voltage in the external circuit increases, the pointer deflection increases and the pointer deflection decreases with increasing current.
• Therefore, the resulting torque is directly proportional to the voltage and inversely proportional to the current.
• When the electrical circuit being tested is open, the torque due to the voltage coil will be maximum and the pointer shows "infinity" means that there is no short circuit across the circuit and has maximum resistance inside the circuit under test.
• If there is a short-circuit pointer that shows 'zero', which means that 'NO' resistance inside the circuit is being tested.
Philosophy of work based on ohm-meter or ratio-meter. The deflection torque is produced with the mega meter because of the magnetic field produced by the voltage and current, similarly to 'Ohm's Law'
The megger pair varies in the ration with V / I, (Ohm's law: -V = IR or R = V / I). The electrical resistance to be measured is connected through the generator and in series with the baffle coil.
The torque produced will be in the opposite direction if the current supplied to the coil.
1. High resistance = No current: - No current will flow through the deflection coil, if the resistance is very high, ie the infinity position of the pointer
2. Small resistance = High current: - If the circuit measures a small resistance, it allows a highelectric current to pass through the deflection coil, ie the torque produced make the pointer to set to 'ZERO'.
3. Intermediate resistance = varied current: - If the measured resistance is intermediate, produce the aligned pair or adjust the pointer between the range of 'ZERO to INIFINITY'
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