08-08-2012, 04:32 PM
Power Quality
power quality 2 clmns psrmcr.docx (Size: 207.51 KB / Downloads: 48)
ABSTRACT:-
”The Energy is neither be created nor be destroyed”. “Energy saved is energy produced”
Power quality is simply the interaction of electrical power with equipment. If electrical equipment operates correctly and reliably without being damaged or stressed ,we would say that the electric power is good quality. On the other hand, if the electrical equipment malfunctions, is unreliable or is damaged during normal usage, we would suspect that the power quality is poor.
INTRODUCTION:-
Our technological world has become deeply dependent upon the continuous availability of electrical power .In most countries, commercial power is made available via nationwide grids, interconnecting numerous generating stations to the loads. The grid must supply basic national needs of residential, lighting, heating, refrigeration, air conditioning, and transportation as well as critical supply to governmental, industrial, financial, commercial, medical and communications communities. Commercial power literally enables today’s modern world to function at its busy pace. Sophisticated technology has reached deeply into our homes and careers, and with the advent of e-commerce is continually changing the way we interact with the
rest of the world.
Oscillatory
An oscillatory transient is a sudden change in the steady-state condition of a signal's voltage, current, or both, at both the positive and negative signal limits, oscillating at the natural system frequency. In simple terms, the transient causes the power signal to alternately swell and then shrink, very rapidly. Oscillatory transients usually decay to zero within a cycle (a decaying oscillation). These transients occur when you turn off an inductive or capacitive load, such as a motor or capacitor bank. An oscillatory transient results because the load resists the change. This is similar to what happens when you suddenly turn off a rapidly flowing faucet and hear a hammering noise in the pipes. The flowing water resists the change, and the fluid equivalent of an oscillatory transient occurs.
Under voltage
Under voltages are the result of long-term problems that create sags. The term “brownout” has
been commonly used to describe this problem, and has been super ceded by the term under voltage. Brownout is ambiguous in that it also refers to commercial power delivery strategy during periods of extended high demand. Under voltages can create overheating in motors, and can lead to the failure of nonlinear loads such as computer power supplies. The solution for sags also applies to under voltages. However, a UPS with the ability to adjust voltage using an inverter first before using battery power will prevent the need to replace UPS batteries as often. More importantly, if an under voltage remains constant, it may be a sign of a serious equipment fault, configuration problem, or that the utility supply needs to be addressed.
Over voltage
Over voltages (can be the result of long-term problems that create swells. An overvoltage can be
thought of as an extended swell. Over voltages are also common in areas where supply transformer tap settings are set incorrectly and loads have been reduced. This is common in seasonal regions where communities reduce in power usage during off-season and the output set for the high usage part of the season is still being supplied even though the power need is much smaller. It’s like putting your thumb over the end of a garden hose. The pressure increases because the hole where the water comes out has been made smaller, even though the amount of water coming out of the hose remains the same. Overvoltage conditions can create high current draw and cause the unnecessary tripping of downstream circuit breakers, as well as overheating and putting stress on equipment.
Frequency Variations:-
Frequency variation is extremely rare in stable utility power systems, especially systems
interconnected via a power grid. Where sites have dedicated standby generators or poor power
infrastructure, frequency variation is more common especially if the generator is heavily loaded. IT equipment is frequency tolerant, and generally not affected by minor shifts in local generator frequency. What would be affected would be any motor device or sensitive device that relies on steady regular cycling of power over time. Frequency variations may cause a motor to run faster or slower to match the frequency of the input power. This would cause the motor to run inefficiently and/or lead to added heat and degradation of the motor through increased motor speed and/or additional current draw.
To correct this problem, all generated power sources and other power sources causing the frequency variation should be assessed, then repaired, corrected, or replaced.
CONCLUSIONS:
The widespread use of electronics has raised the awareness of power quality and its affect on the critical electrical equipment that businesses use. Our world is increasingly run by small microprocessors that are sensitive to even small electrical fluctuations. These microprocessors can control blazingly fast automated robotic assembly and packaging line systems that cannot afford downtime. Economical solutions are available to limit, or eliminate, the affects of power quality disturbances. However, in order for the industry to communicate and understand power disturbances and how to prevent them, common terms and definitions are needed to describe the different phenomena. This paper has attempted to define and illustrate power quality disturbances.
power quality 2 clmns psrmcr.docx (Size: 207.51 KB / Downloads: 48)
ABSTRACT:-
”The Energy is neither be created nor be destroyed”. “Energy saved is energy produced”
Power quality is simply the interaction of electrical power with equipment. If electrical equipment operates correctly and reliably without being damaged or stressed ,we would say that the electric power is good quality. On the other hand, if the electrical equipment malfunctions, is unreliable or is damaged during normal usage, we would suspect that the power quality is poor.
INTRODUCTION:-
Our technological world has become deeply dependent upon the continuous availability of electrical power .In most countries, commercial power is made available via nationwide grids, interconnecting numerous generating stations to the loads. The grid must supply basic national needs of residential, lighting, heating, refrigeration, air conditioning, and transportation as well as critical supply to governmental, industrial, financial, commercial, medical and communications communities. Commercial power literally enables today’s modern world to function at its busy pace. Sophisticated technology has reached deeply into our homes and careers, and with the advent of e-commerce is continually changing the way we interact with the
rest of the world.
Oscillatory
An oscillatory transient is a sudden change in the steady-state condition of a signal's voltage, current, or both, at both the positive and negative signal limits, oscillating at the natural system frequency. In simple terms, the transient causes the power signal to alternately swell and then shrink, very rapidly. Oscillatory transients usually decay to zero within a cycle (a decaying oscillation). These transients occur when you turn off an inductive or capacitive load, such as a motor or capacitor bank. An oscillatory transient results because the load resists the change. This is similar to what happens when you suddenly turn off a rapidly flowing faucet and hear a hammering noise in the pipes. The flowing water resists the change, and the fluid equivalent of an oscillatory transient occurs.
Under voltage
Under voltages are the result of long-term problems that create sags. The term “brownout” has
been commonly used to describe this problem, and has been super ceded by the term under voltage. Brownout is ambiguous in that it also refers to commercial power delivery strategy during periods of extended high demand. Under voltages can create overheating in motors, and can lead to the failure of nonlinear loads such as computer power supplies. The solution for sags also applies to under voltages. However, a UPS with the ability to adjust voltage using an inverter first before using battery power will prevent the need to replace UPS batteries as often. More importantly, if an under voltage remains constant, it may be a sign of a serious equipment fault, configuration problem, or that the utility supply needs to be addressed.
Over voltage
Over voltages (can be the result of long-term problems that create swells. An overvoltage can be
thought of as an extended swell. Over voltages are also common in areas where supply transformer tap settings are set incorrectly and loads have been reduced. This is common in seasonal regions where communities reduce in power usage during off-season and the output set for the high usage part of the season is still being supplied even though the power need is much smaller. It’s like putting your thumb over the end of a garden hose. The pressure increases because the hole where the water comes out has been made smaller, even though the amount of water coming out of the hose remains the same. Overvoltage conditions can create high current draw and cause the unnecessary tripping of downstream circuit breakers, as well as overheating and putting stress on equipment.
Frequency Variations:-
Frequency variation is extremely rare in stable utility power systems, especially systems
interconnected via a power grid. Where sites have dedicated standby generators or poor power
infrastructure, frequency variation is more common especially if the generator is heavily loaded. IT equipment is frequency tolerant, and generally not affected by minor shifts in local generator frequency. What would be affected would be any motor device or sensitive device that relies on steady regular cycling of power over time. Frequency variations may cause a motor to run faster or slower to match the frequency of the input power. This would cause the motor to run inefficiently and/or lead to added heat and degradation of the motor through increased motor speed and/or additional current draw.
To correct this problem, all generated power sources and other power sources causing the frequency variation should be assessed, then repaired, corrected, or replaced.
CONCLUSIONS:
The widespread use of electronics has raised the awareness of power quality and its affect on the critical electrical equipment that businesses use. Our world is increasingly run by small microprocessors that are sensitive to even small electrical fluctuations. These microprocessors can control blazingly fast automated robotic assembly and packaging line systems that cannot afford downtime. Economical solutions are available to limit, or eliminate, the affects of power quality disturbances. However, in order for the industry to communicate and understand power disturbances and how to prevent them, common terms and definitions are needed to describe the different phenomena. This paper has attempted to define and illustrate power quality disturbances.