Until now, food, clothing, shelter and receiving good health services were considered the basic requirements for an individual to live and sustain. Now, can you consider spending one day without your mobile, TV or computer? With the advent of technological advancement and extensive applications of power electronic equipment, other needs of Heating, Lighting, Communication, Entertainment etc; which are dependent on reliable power, have become a part and parcel of the consumers daily lives. In fact, the use of some of this equipment has become imperative. For e.g. the consumers who fall sick because they cannot use their heating devices for bath due to power outage and whose devices breakdown due to frequent interruptions have to put up with the indirect costs of poor power quality (e.g. medical, repair and replacement costs) or take the case of a person losing all her/his contacts, communication and even memorable photographs due to crash of computer hard disk impacted by poor power quality; it means a lifetime memory erased forever that cannot even be valued.
This blog attempts to capture, (1) the effects of poor power quality on common masses and (2) mitigation techniques & solutions that can be applied to minimize interruptions, avoid safety breach and equipment damage.
As a common man, ‘Power Quality’ would generally mean supply without interruptions and at an affordable rate per unit. However, PQ actually refers to the extent to which the power received at our homes is free of disturbances which would otherwise cause equipment to malfunction or fail. The common perception of masses is that PQ is the power distribution utility’s responsibility and all issues/interruptions are because of their network infrastructure and services. It is being understood that as an end-user neither we have any control over it nor are we responsible for it. While there are certain external factors such as lightning, rain, winds, etc. that cause PQ problems, it will be hard to imagine that many of the PQ issues are due to what happens inside customer’s premises. About 70-80% of power quality problems are caused inside a premise, due to equipment/appliance with low immunity or inadequate building wiring or incorrect grounding and also including large loads sharing the same circuits. These problems can be compounded by more frequent starting, running and stopping of electronic appliances and critical systems. If a building is more than 15 years old, it probably wasn’t designed to meet the demands of today’s consumer devices and appliances.
KEY ELECTRICAL LOADS IN RESIDENTIAL SECTOR
Before we move ahead to recognize the effect of poor PQ on common masses, let us first understand their typical energy consumption pattern. Below fig depicts the percentage breakdown of consumption pattern in residential sector in India based on consolidated data available for year 2011.
Although common masses in general may be unfamiliar with the term PQ, they are likely to be aware of consequences of PQ problems. PQ problems affect many appliances in home, especially electronic equipment, the use of which is increasing more and more in households. Some of the regularly used electrical loads like Personal Computers, sophisticated Stereo Systems, Microwave Ovens, Air Conditioner, Refrigerator, Satellite Systems and other appliances may be damaged or may fail prematurely if they are not protected from harmful voltage and frequency surges and related PQ disturbances.
PQ DISTURBANCES ON KEY APPLIANCES AND ITS EFFECTS
Power Distribution Utilities strive to provide highly reliable and consistent electric power, however it is not possible for them to maintain perfectly constant voltage at all times. In the course of their operations, voltage will inevitably fluctuate, sometimes due to the design of the supply network, internal switching of electricity supply or sometimes due to varying consumption patterns of customers for e.g. the starting and stopping of residential heavy loads like lift , pumps, drilling machines or appliances like refrigerators, ACs, geysers , etc. These voltage fluctuations create PQ issues like Surges/Spikes, Transients, Swells/Sags, Momentary Interruptions, etc. which are harmful to sensitive equipment/appliances.
Below fig depicts some of the physical manifestations of Power Quality issues caused in the electrical network due to customers’ loading/consumption pattern across key equipment.
While above indicated are the causes of PQ issues in the electrical network, at the same time it also has effects on the customers (and their equipment) back. Following are some of the observed effects of poor PQ at homes appliances:
- Digital equipment like computers are the most affected devices due to Momentary Interruptions resulting in loss of data, if UPS/battery back is not used
- Digitally controlled white goods or appliance giving way or not functioning in low voltage areas
- Turning large loads (like Room ACs, Refrigerator, Washing Machine) ON/OFF also causes Swells/Sags. The circuit supplying power to this equipment may be overloaded or have an internal wiring deficiency
- Too many large loads, lightning, etc. on the same circuit can cause a transient impulse and damage electronic devices
- Sometimes turning on grinding machine, hair dryer, vacuum cleaner etc. may have impact on TV and there is some noise interference
- Some other and important effects like electric shock, electrical faults causing fire, etc. are safety related risks associated due to poor PQ at homes
There are number of factors that can cause power disturbances, including lightning strikes, undersized wiring, short-circuit in home wiring or power system outages. Poor grounding and improper wiring also contributes to home power quality problems. Depending on the size of the voltage fluctuation, PQ problems can vary in severity, ranging from brief malfunction to immediate equipment failure. Even the problems that last shorter than a second may result in considerable economical losses for the users in many aspects.
AFFORDABLE PQ INITIATIVES AT HOMES
There is no doubt that the availability of electric power with high quality is crucial for the running of the modern society. Therefore, it is necessary that consumers also play their part in avoiding PQ problems and avoid huge losses related with them. For e.g. to reduce electric shock or faults resulting into fire, it is very important to make the electrical system error proof, right from the design to the installation. A proper design of the electrical system in the house is extremely crucial and professional advice must be sought for the same.
If there is recurring problems with electronic equipment, following affordable and common measures can minimize them. Moreover these measures will help reduce PQ issues and improve the life and efficiency of electrical equipment.
- Proper wiring including upsizing such wiring system catering heavy loads and good grounding of entire home is essential for electronic equipment to operate smoothly and perform better
- Checking appliances for loose or damaged plugs, connections, and repairing or replacing them
- Checking home fuse box or panels and ensuring that sensitive loads (like computer, TV, etc.) aren’t sharing a circuit with your large switching loads (refrigerator, washing machine, ovens, etc.). Labeling fuses showing which appliances are on which circuit is a good way of doing this OR moving offending equipment like dryers, heaters, etc. to a different circuit can do the trick
- Using Transient Voltage Surge Suppressors (TVSS) are the most basic, simplest and least expensive power protection device that protect against high transient level voltages
- Using voltage regulators that maintains a constant voltage level as well as provide protection. These regulators do not rely on batteries and therefore have a long life and also extend the life of electrical equipment
- Using a home UPS system may be necessary to overcome low voltage impact on sophisticated digital devices like TV etc.
Thus, we note that Power Quality has become a matter of growing concern in recent years owing to a daily rise in use of non-linear sensitive loads at home level. The fast growing technologies like distributed generations, sensitivity of automation and electronic devices, etc. are emerging as part of modern distribution system.
As an end user, we make significant investment in our home appliances; hence it is our responsibility to protect those appliances and ourselves against PQ related harm. Through regular inspections/preventive maintenance of the electrical installation, small steps like right planning and procurement of equipment besides overseeing implementation by a trained/certified/authorized electrician at home can help customer protect themselves against PQ problems to a large extent. It is said that ‘Prevention is better than cure’. Therefore, rather than things getting worse and the PQ issues getting aggravated, weak points in the electrical system should be identified and foreseen and basic initial steps must be undertaken This will help avoiding failure of expensive gadgets, and preventing fire or loss of property or life with improved performance of the key equipments.
(1) Residential buildings in India: Energy use projections and savings potentials – Global Buildings Performance Network, Oct 2014
(3) Electrical Safety in the Home – Leonardo Energy
(4) Power Quality for Residential Customers – Platts, a division of The McGraw Hill Companies, Inc (2003)
(5) Power Quality in Your Home – Pacific Gas and Electric Company, 2012