Power Monitoring Solution

Electric power quality is the degree to which the voltage, frequency, and waveform of a power supply system conform to established specifications. Good power quality can be defined as a steady supply voltage that stays within the prescribed range, steady AC frequency close to the rated value, and smooth voltage curve waveform (which resembles a sine wave). In general, it is useful to consider power quality as the compatibility between what comes out of an electric outlet and the load that is plugged into it.The term is used to describe electric power that drives an electrical load and the load's ability to function properly. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality, and many more causes of such poor quality power.

The electric power industry comprises electricity generation (AC power), electric power transmission and ultimately electric power distribution to an electricity meter located at the premises of the end user of the electric power. The electricity then moves through the wiring system of the end user until it reaches the load. The complexity of the system to move electric energy from the point of production to the point of consumption combined with variations in weather, generation, demand and other factors provide many opportunities for the quality of supply to be compromised.

While "power quality" is a convenient term for many, it is the quality of the voltage—rather than power or electric current—that is actually described by the term. Power is simply the flow of energy, and the current demanded by a load is largely uncontrollable.
 

There are many ways in which electric power can be of poor quality, and many more causes of such poor quality power. The most common types of Power Quality problems are:

1. Voltage sag (or dip): A decrease of the normal voltage level between 10% and 90% of the nominal rms voltage at the power frequency, for durations of 0,5 cycle to 1 minute. This can be caused by faults on the transmission or distribution network, faults in consumer’s installation, connection of heavy loads and start-up of large motor.
2. Very short interruptions: Total interruption of electrical supply for duration from few milliseconds to one or two seconds. This is mainly due to the opening and automatic reclosure of protection devices to decommission a faulty section of the network. The main fault causes are insulation failure, lightning and insulator flashover.
3. Long interruptions: Total interruption of electrical supply for duration greater than 1 to 2 seconds. This can be caused by equipment failure in the power system network, storms and objects (trees, cars, etc) striking lines or poles, fire, human error, bad coordination or failure of protection devices.
4. Voltage spike: Very fast variation of the voltage value for durations from a several microseconds to few milliseconds. These variations may reach thousands of volts, even in low voltage. This can be caused by lightning, switching of lines or power factor correction capacitors, disconnection of heavy loads.
5. Voltage swell: Momentary increase of the voltage, at the power frequency, outside the normal tolerances, with duration of more than one cycle and typically less than a few seconds. This is mainly due to the opening and automatic reclosure of protection devices to decommission a faulty section of the network. The main fault causes are insulation failure, lightning and insulator flashover.
6. Harmonic distortion: The presence of harmonics in the power system. Harmonics are sinusoidal voltages or currents having frequencies that are integer multiples of the fundamental power frequency. This can be caused by non-linear loads, such as computers, variable speed drives, and other electronic equipment.
7. Voltage fluctuation: The change in voltage magnitude over time. This can be caused by the operation of large loads, such as motors, or by the connection of new loads to the system.
8. Noise: The presence of unwanted electrical signals in the power system. This can be caused by radio frequency interference (RFI), electromagnetic interference (EMI), and other sources.
9. Voltage Unbalance: The unequal distribution of voltage among the three phases of a three-phase power system. This can be caused by unbalanced loads, transformer failures, and other factors.
 

To prevent power quality problems, you can take the following measures:

1. Use high-quality electrical equipment: Using high-quality electrical equipment, such as motors, transformers, and inverters, can reduce the occurrence of power quality problems.
2. Improve grounding and bonding: Proper grounding and bonding of electrical systems can help to eliminate ground loops and reduce noise and interference.
3. Install surge protection devices (SPDs): SPDs can protect electrical equipment from internal or external surges, which can be generated by switching processes, such as switching inductive or capacitive loads, fuse, or breaker openings in an inductive circuit.
4. Regular maintenance and monitoring: Regular maintenance and monitoring of electrical equipment can help to detect and prevent power quality problems.
5. Avoid overloading circuits: Overloading circuits can cause voltage drops and other power quality problems. Make sure that the electrical load is distributed evenly across the circuits.