Power quality is really important for the distribution and also the transmission network. The major purpose of these systems is to provide proper power to the customer and this power must be reliable and consistent for a specified voltage and frequency. The power quality is affected due to various problems some of them are transients, overvoltage, sags, etc. These problems could cause a lot of damages to the machinery or to the equipment, the equipment life will be depended upon the power quality. The proper power quality would allow the equipment to operate in a proper manner and thus the life of the equipment can be improved by this too.
- Current transformer
- Voltage transformer
- Instrument transformer
- Partial discharge
- Insulation testing
- How to prevent double voltage
What are the problems that can be caused due to the improper power supply?
- Malfunction of the equipment
- Excessive wear or equipment life will be affected
- Cost is increased due to the downtime
- High maintenance and repair
- Time and expense
What is the importance of good power quality?
The minor fluctuations could affect the electronic equipment, new electronic loads can create improper conditions. In order to carry out any industrial process, we need to use certain electrical and electronic equipment and because of the improper power quality, this equipment won’t operate properly so it would affect the industrial process. The electronic equipment which is new will be more sensitive to the variations in power.
Due to the power problems the electronic device can create harmonic distortion, many of the electronic devices are affected by the power problems. The source of the power problems can also badly influence electronic devices. So we must make sure that the power supplied to the equipment has good quality so that the equipment can carry out its operation.
How to protect the equipment from power quality problems?
- Improve the power supply
- Equipment immunizing
- Disturbance control
What are the major causes of the power problems?
- Outdated electrical system
- Failure of the equipment
- Improper maintenance
- Overloaded circuit
- Wiring and grounding would not be done properly
- Transmission system problems
- Electronic loads won’t be suitable for the building
- There is no mitigation solution for the new equipment
- Circuit protection could be improper
The change in the magnitude of the voltage and frequency could affect the power quality. The magnitude could be varied due to the change in the load. The frequency change could happen because of the system dynamics or due to the harmonics.
How can we determine the power quality problems?
- The automated system would stop its operation without any reason
- The circuit breaker could trip without any overload
- Faulty equipment
- Operation of the equipment could be affected because of the thunderstorm
- Failure of electronic system
- Overheating of transformer
- Failure of the motor
- Failure of the capacitor
What are the major power quality issues?
- Voltage sag
- Voltage swell
- Waveform distortion
- Frequency variations
- Voltage fluctuation
The magnitude of the voltage could change or it can also be explained as a reduction in voltage. During this power problem, the voltage could be reduced by more than sixty percent. The voltage sags can be caused due to the failure in the transmission and distribution network, it could also happen due to the connection of heavy loads. Voltage sags can also be caused due to the starting of the motor because during motor start-up it would take more power than its requirement and this can be solved by using a variable speed drive. Basically, the voltage sag is short-term low voltage this could be triggered by the utility switching and this could damage the equipment.
There are different types of voltage sags according to the time duration and voltage magnitude. The different types of voltage sags are instantaneous sag, momentary sag, and temporary sag.
We can solve the voltage sag problem by using a single-phase UPS or we can also use a constant voltage transformer.
The transient is the short-term high voltage, mostly it is caused because of the lightning strikes. During the power surge, the voltage will be 110% or above, this problem could also happen if the heavy electrical equipment has been turned off. Due to the transient or surge many equipment failures could happen because of the powerful transients.
Surges could be continuous or momentary, the continuous surge would range from 250-1000v it could be caused due to motor operation. Momentary surges could range from 250-3000v and this can be caused due to the inductive load switching. There are two types of transients and they are impulsive transients and oscillatory transients.
Lightning would create a quick variation in the voltage and current level and this power problem can be categorized as the impulsive transients. This problem could arise if the grounding is not proper. A quick variation in the current or voltage can be called oscillatory transient and this could be created if we turn off the inductive or capacitive load. This type of transient occurs because the load resists the change.
Surge suppressor, voltage regulators, uninterrupted power supplies, power conditioners.
This is the increase in the voltage for short time, it is the exact opposite of the voltage sag. This type of power problem is caused due to the reduction of the load in a circuit and it could also happen due to the faults in the neutral connection. The major consequences due to this could be electrical contact degradation, flickering lights, insulation degradation, etc.
UPS, power line conditioners
This is a power problem where there is no supply voltage or can also be described as losing the whole power. The interruption is further classified into momentary interruption and temporary interruption. The momentary interruption could last up to three seconds while the temporary interruption could last for one minute. The interruption can be caused due to the electrical supply grid damage, it can be caused due to the circuit breaker tripping,
The waveform distortion can be explained as a steady-state deviation from the sine wave of the power frequency. The waveform distortion is divided into five types and they are DC offset, harmonics, inter-harmonics, notching, and noise. The DC offset is the inducing of the DC current to the AC distribution system, this can happen due to any component failure. DC current could be induced due to overheating or because of the transformer saturation. Harmonic is the variation or change in the power frequency and the symptoms are circuit breaker tripping, transformer overheating, etc.
The voltage disturbances which are created by the electronic devices are called notching this type of power problem would create data transmission problems, data loss. The noise in the power system can be described as an unwanted voltage or current that is created by the electronic device. The major problems that can be caused by noise are component failure, equipment malfunction, etc.
Replace the damaged equipment, harmonic filters, UPS
The frequency variation is the change in the frequency of the power system from its specified value. This type of problem is caused due to the changes in load, this type of power problem is very rare. It can also be caused due to the poor power infrastructure and also in case if the generator is heavily loaded.
The change in the magnitude of the voltage is the voltage fluctuation, mostly this power problem is caused by high power loads like a motor. The operation of the high power loads would create small frequency voltage variations. The major problem which is caused by this power problem is that it would affect the operation of the electrical and electronic devices.
Power line conditioning, UPS
What are the advantages of good power quality?
- Energy can be saved
- Temperature rise can be controlled
- Equipment life would be improved
- The equipment would function properly
- Less maintenance cost
- Improved production