The Power Quality Issues And Problems

Power Quality:

Generally power quality problems defined as: ‘Any power problem that results in failure or misorientation of customer equipment, demonstrates itself as an economic burden to the user, or produces negative impacts on the environment.’When applied to the instrumentality crane industry, the power issues which disgrace power quality include:

• Power Factor
• Harmonic Distortion
• Voltage Transients
• Voltage Sags or Dips
• Voltage Swells.

The AC and DC variable speed drives employed on control panel container cranes are significant subscribers to total harmonic current and voltage deformation. Whereas SCR phase control creates the worthy average power factor, DC SCR drives engage at less than this. In addition, line incising occurs when SCR’s change by reversal, creating ephemeral peak recovery voltages that can be 3 to 4 times the nominal line voltage depending upon the system impedance and the size of the drives. The frequency and austereness of these power system disruptions varies with the speed of the drive. Harmonic current injectant by AC and DC drives will be highest when the drives are operating at deadly speeds. Power factor will be lowest when DC drives are operating at deadly speeds or during initial quickening and retardation periods, increasing to its maximum value when the SCR’s are phased on to produce rated or baseborn speed.

Above base speed, the power factor fundamentally remains constant.regrettably container cranes can spend healthy time at depleted speeds as the operator seeks to spot and land containers. inadequate power factor places a greater kVA demand burden on the usefulness or engine-alternator power source. Low power factor loads can also impact the voltage stability which can at long last result in prejudicious effects on the life of sensible electronic equipment or even intermittent misfunction.

Voltage oscillations created by DC drive SCR line putting down, AC drive voltage choppily and high frequency harmonic voltages and currents are all igneous sources of noise and disturbance to spiritualist electronic equipment.

It has been our receive that end users often do not associate degree power quality problems with instrumentality cranes, either because they are totally incognizant of such issues or there was no economic aftermath if power quality was not self-addressed. Before the Parousia of solid-state power supplies, Power factor was sensible and harmonic current injection was minimal. Not until the crane Population manifolded, power demands per crane increased, and static power conversion became the way of life, did power quality issues begin to come out Even as harmonic distortion and power Factor issues came up, no one was really devised.

Even today, crane builders and electrical drive system marketeers avoid the issue during competitive adjuring for new cranes. Rather than focus on awareness and understanding of the potential issues, the power quality issue is deliberately or accidentally ignored. Power quality problem solutions are available. Although the solutions are not free, in most cases, they do represent a good return on investituret. However, if power quality is not specified, it most likely will not be delivered.