Insulated and Covered conductor systems for low and medium voltage over head distribution lines
Overhead distribution systems can be categorized into two broad heads based on voltage rating and insulation system. Distribution system based on voltage rating is broadly either low voltage (upto 1.1 KV) or medium voltage (upto 36KV). Transmission & Sub-transmission of power is done at higher voltages. Voltages between 33KV and about 230kv , called high voltage are used for sub-transmission & transmission of power. Voltage level above 230kv upto about 800kv is called EHV or extra high voltage and voltage level above 800kv is called UHV or Ultra High Voltage.
We now also have HVDS systems where lines right upto consumers small single phase transformers are run at medium voltage. In this system LV mains are conspicuous by their absence. Categories based on insulation type are either bare or covered.
Supreme range of soil & rock Anchors
Used to anchor into concrete, masonry, stone.
With time, the evaluation of anchors have led to different designs.
More than one anchor type may be suitable for a particular purpose
Thus there are some salient features which need to be examined before choosing any anchor.
SALIENT FEATURES WHILE CHOOSING AN ANCHOR:
- Base Material
An insight into Design, Development & Testing of insulation piercing Connectors for LV Application.
- Designed for Indoor and Outdoor Applications.
- Non-tension tap and splice applications.
- Used in insulated Secondary distribution lines.
Details regarding the material:
Austenite stainless steel confirming UNI 6900
C (0.08), Mn (2.00), Si (1.00),P (0.045), Ni (8.00/12.00),Cr (18.00/20.00)
C (0.15-0.25), Mn (0.60-0.90), Si (0.15-0.35), P(0.03)
Concept of Wind Induced Oscillations
Oscillations in conductors occur due the following phenomena :
1.Aeolian or Vertical Vibrations:
This is the most common type of vibration that results due to vortex shedding under laminar flow of wind. These are low amplitude medium frequency (3 – 60 Hz for wind speeds of 1-8 m/s). Sometimes, additional sinusoidal waves of different frequencies arise on the line, corresponding to a higher mode of vibrations. These vibrations are in the vertical plane and exert continuous alternating bend stresses on the conductor strands and eventually may lead fatigue failure of the conductor. Purview of this article is to cover protection of conductor from Aeolian Vibration.
It is also termed as Long wave vibrations and is characterized by low frequencies of 0.1 to 1 Hz. This phenomenon is most common when there is a sleet covering of the cable. Ice coating creates irregular edges and surfaces, which disturb the airflow, which breaks away at these points to induce a certain self-excitation. Thus the system becomes susceptible to vibrations subject to resonance. This effect is not so pronounced in India. Conditions that are conducive for galloping are – Low pressure area with High winds, temperature between 0 and -5 °C.
Automation is the process of eliminating errors occurring due to human limitations & negligence and ensuring uniformity and consistency in the process.
Conventionally,Hard-wired logic is used for the purpose of automation however they are subject to many limitations. These limitations are overcome by using PLC Based Automation.
Prior to PLC’s, many control tasks were performed by contractors, control relays, and other electromechanical devices. This is often referred to as hard -wired control.Circuit diagrams had to be designed , electrical components,specified and installed and wiring lists created. Electricians would then wire the components necessary to perform a specific task. If an error was made, the wires had to be reconnected correctly.A change in function or system expansion required extensive component changes and rewiring.
The Programmable Logic Control(PLC) is a digital computer used for automation of an electromechanical process.