Power Quality Monitoring is concerned with issues such as detecting phase imbalances and particularly whether all phasors have the same magnitude and are phase-shifted symmetrically by 120-degrees to each other.
In the mid-eighties, as part of my function, I was asked to help and solve a problem of one of our client’s constant complaints about “power failures”. This client was the National Accelerator Centre (NAC) in Faure, Western Cape. Today it is called the iThemba LABS. According to their website, this is the largest accelerator […]
Consequence of Weaknesses in Power Quality Read More »
Throughout my time in the power transmission and distribution industry I have probably had experiences that many others may never have. In a previous post, I talked about the current and voltage unbalances and how a large factory in the Western Cape in South Africa was severely affected by negative phase sequencing. In this post
Power Network Disturbances Read More »
To mitigate the effects of Load-Shedding, many homeowners have decided to install PV Solar Energy systems. And, as I said before, they are more worried about how much it would cost than the quality of the products. If they can pay the lowest possible price for the entire installation, they are happy and do not
Power Quality Issues Caused by Distributed Generation Read More »
Any repetitive signal, such as three-phase Alternating Current (AC) Voltages and Currents, can be represented as the rotation of a vector around a point. In a balanced three-phase network, the magnitudes of the voltages and currents in all three phases are the same and these phases voltages and currents are shifted symmetrically by 120 degrees
Rotating Voltage and Current Vectors Read More »
Practical imperfections which can result in unbalances are: A three-phase equipment such as induction motor with unbalance in its windings. If the reactance of three phases is not same, it will result in varying current flowing in three phases and give out system unbalance. With continuous operation, motor’s physical environment cause degradation of rotor and
Causes of Unbalanced Voltages and Currents Read More »
Transmission lines with high and extra-high voltage that are untransposed, meaning the conductors are not positioned at the corners of an equilateral triangle and lack an overhead grounding wire (OGW), significantly contribute to the generation of negative-sequence voltages and, to a lesser extent, zero-sequence voltages. As the electrical load increases, the incidence of negative-sequence voltages
Untransposed Transmission Lines Read More »
In a balanced three-phase network, the magnitudes of the voltages and currents in all three phases are the same and these voltages and currents phase are shifted symmetrically by 120 degrees to each other. If the magnitudes are not the same and phase-shifts are different from the 120 degrees, the network is unbalanced. Eskom strive
Phase Imbalance in Distribution Networks Read More »
When switchgear is poorly maintained and operated continuously, it is only a matter of time before something significant occurs. However, if these extreme events go unnoticed, the consequences can be long-lasting. During load-shedding, circuit-breakers should be opened when load-shedding starts and closed when load-shedding ends. Unfortunately, the contacts of these circuit-breakers are often concealed. As
Load Shedding Consequences Read More »
