Ans: The duty cycle is the fraction of time that a system is in an "active" state.
- duty cycle
where
- τ is the duration that the function is active high(normally when the signal is greater than zero);
- Τ is the period of the function.
Wednesday, January 27, 2010
Sunday, January 24, 2010
Ques:Why OC test is conducted on low voltage side?
ANS:The test is to determine the shunt branch parameters of the equivalent ckt of the transformer. One of the winding is connected to the rated voltage and other winding is kept open circuited. The test can be done from HV side too but the losses the power consumption and the risks will be much higher!
ANS:The test is to determine the shunt branch parameters of the equivalent ckt of the transformer. One of the winding is connected to the rated voltage and other winding is kept open circuited. The test can be done from HV side too but the losses the power consumption and the risks will be much higher!
Ques:Difference between Neutral and Ground wires?
ANS:Ground wire:Ground or earth in a mains (AC power) electrical wiring system is a conductor that provides a low impedance path to the earth to prevent hazardous voltages from appearing on equipment.Ground wires generally do not carry currents.
Neutral Wire:The neutral is the return for the live feed from your circuit and is bonded at the main panel to the grounding conductor so that any stray currents caused by equipment faults will go back to the utility transformer.It generally carries current in its normal operation.
ANS:Ground wire:Ground or earth in a mains (AC power) electrical wiring system is a conductor that provides a low impedance path to the earth to prevent hazardous voltages from appearing on equipment.Ground wires generally do not carry currents.
Neutral Wire:The neutral is the return for the live feed from your circuit and is bonded at the main panel to the grounding conductor so that any stray currents caused by equipment faults will go back to the utility transformer.It generally carries current in its normal operation.
Tuesday, January 5, 2010
Q.what is slip rings?
A slip ring is a method of making an electrical connection through a rotating assembly.A slip ring consists of a conductive circle a shaft and insulated from it. Electrical connections from the rotating part of the system, such as the rotor of a generator, are made to the ring. Fixed contacts or brushes run in contact with the ring, transferring electrical power or signals to the exterior, static part of the system.This system is similar brushes to the commutator in many types of DC Motors.
A slip ring is a method of making an electrical connection through a rotating assembly.A slip ring consists of a conductive circle a shaft and insulated from it. Electrical connections from the rotating part of the system, such as the rotor of a generator, are made to the ring. Fixed contacts or brushes run in contact with the ring, transferring electrical power or signals to the exterior, static part of the system.This system is similar brushes to the commutator in many types of DC Motors.
Monday, January 4, 2010
Q.what are the basic types of Rotor?
Ans-
1.Squirrel cage-The most common rotor is a squirrel-cage rotor. It is made up of bars of either solid copper (most common) or aluminum that span the length of the rotor, and are connected through a ring at each end. The rotor bars in squirrel-cage induction motors are not straight, but have some skew to reduce noise and harmonics.
2.Slip ring or wound rotor-A slip ring rotor replaces the bars of the squirrel-cage rotor with windings that are connected to slip rings. When these slip rings are shorted, the rotor behaves similarly to a squirrel-cage rotor; they can also be connected to resistors to produce a high-resistance rotor circuit, which can be beneficial in starting.
3.Solid core rotor-A rotor can be made from a solid mild steel. The induced current causes the rotation.
Ans-
1.Squirrel cage-The most common rotor is a squirrel-cage rotor. It is made up of bars of either solid copper (most common) or aluminum that span the length of the rotor, and are connected through a ring at each end. The rotor bars in squirrel-cage induction motors are not straight, but have some skew to reduce noise and harmonics.
2.Slip ring or wound rotor-A slip ring rotor replaces the bars of the squirrel-cage rotor with windings that are connected to slip rings. When these slip rings are shorted, the rotor behaves similarly to a squirrel-cage rotor; they can also be connected to resistors to produce a high-resistance rotor circuit, which can be beneficial in starting.
3.Solid core rotor-A rotor can be made from a solid mild steel. The induced current causes the rotation.
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