DETERMINATION OF ACTUAL DISTANCES FOR INSTALLATION OF A 100 kVA NON-SOUNDPROOF
POWER GENERATOR AT RESIDENTIAL AREAS Etinamabasiyaka E. Ekott*1,
Donatus E. Bassey2, Effiong O. Obisung2 *1 Department of Physics, University
of Uyo, Akwa Ibom State,
Nigeria 2 Department of Physics,
University of Calabar, Cross River State, Nigeria DOI: https://doi.org/10.29121/IJOEST.v4.i1.2020.60 ABSTRACT Power generators should be professionally sited from the residential areas as noise from them demeans the superiority of our living. This work therefore presents determination of actual distances for installation of a 100 kVA non-soundproof power generator at residential areas. Measurements of noise levels with respect to distance, x from the generator were taken and linear regression method was used to analyse the data obtained. Environmental noise models were developed by using the relevant displayed parameters such as the maximum noise level of the generator, the attenuation coefficient and the coefficient of determination. The results obtained from the models developed, L(modelled) were compared with the results obtained from the physical measurements, L(measured) and there was insignificant difference between them. The results reveal that the distances, xc in metres in which its adverse effects covered in the residential areas were 0≤x_c≤67, while the distances, xs in metres at which it can be sited from the residential areas were 68≤x_s≤∞ . With the existence of x, the models developed in this work are recommended to be used as more reliable tools for environmental noise impact assessments. Keywords: Actual Distances; Determination; Installation: Linear Regression; Power Generator; Residential Areas. 1. INTRODUCTION Residential noise is described by World Health Organisation (WHO) as community noise or environmental
noise or domestic noise [1]. The most important sources of community noise
comprise air, rail and road traffic, neighbourhood,
municipal work, and the construction plant, among others. Usually, noise from neighbourhood originates from building and installations
associated with the food preparation business like cafeterias, restaurant, and
discotheques; from recorded or live music; from playgrounds and car parks; from
sporting events including motor sports; and from household animals for example
barking dogs. The major sources of indoor noises include aeration systems, home
appliances; office machines, and neighbours [2]. In the United States of America, the Environmental
Protection Agency (EPA) identified noise as a hindrance since in the 1970s [3].
Then, the agency carried out a main study of noise and has continued to bring
up to date its results. This means that the study of noise is a continuous
phenomenon. As with all pollutants, noise demeans the value of our environment
and is known to produce various negative effects both on structures and on
humans. Noise has escalated to the point where it is currently the most
important peril to the superiority of our existence. This increase in noise can
be attributed to the ever-increasing number of people in the globe and the
growing levels of economic affluence [4]. In this context, noise is defined as unpleasant sound [5]. However, noise can be described as the unwanted sound in the unwanted location at the unwanted occasion. The degree of “unwantedness” is usually a psychological issue since the effects of noise can range from temperate irritation to everlasting hearing loss and may be rated in a different way by special observers [2]. For this reason, it is often exigent to establish the benefits of dropping a specific noise. Noise does affect the inhabitants, humans, fauna, etc, in the natural environment. Some definite places influence noise contacts; so, it is invasive that it became difficult to run away from it. The public opinion polls almost constantly rank noise in the list of the most bothersome residential irritations. General noise sources are industry, neighborhoods and traffic. The industrial noise is one of the most annoying sources of noise complaints [6]. Elevated noise levels of adequate exposure time can result in short-term or permanent hearing damage. This is generally related to those working in industrial plants or operating machinery but can also take place at discotheques or near to aircraft on the ground if the duration is long enough. However, measurable hearing loss from many industrial sounds involves daily exposure for a number of years. On the other hand, community noise intrusions like traffic noise can obstruct speech communication, interfere with sleep and relaxation and disturb the capacity to perform difficult tasks [7]. In 1993, a study carried out by Cornell University indicated that children exposed to noise during classes experienced problem with various cognitive developmental delays in addition to words discrimination. Specifically, the writing learning mutilation called dysgraphic is usually related to stress on environment during classes [8] and [9]. Noise has been connected to vital cardiovascular health risks. In 1999, the WHO drew a conclusion that the existing evidence shown predicted a weak relationship between hypertension and long-term exposure to noise beyond 67 – 70 dBA [10]. More current studies have recommended that noise levels of 50 dB(A) at night may also increase the risks of myocardial infarction by constantly enhancing production of cortisol [11]. Fairly characteristic road levels of noise are adequate
to reduce arterial blood flow and cause elevated blood pressures; in this
situation it seems that a specific part of the populace is more vulnerable to
vasoconstriction. This may occur because the noise bother leads to high
adrenaline intensity to activate vasoconstriction (a reduction of the blood
vessels) or separately through reactions from medical stress. Additional
impacts of elevated levels of sound are high rate of vertigo fatigue, stomach
ulcer and headaches [6]. The
British Columbia Work’s Compensation Board (WCB) has set 85 dB as its highest
tolerant level in the workplace. Above this limit hearing protection should be
used. It states that the threshold of pain is attained at 120 dB and it
classifies 140 dB as excessive hazard level. WHO safety noise levels are
similar while EPA of Nigeria tends to have even a stricter standard of 70 dB as
a maximum safe level of noise in workplace. They gave the safe level around
home to be 50 – 55 dB [12]. Researches
have shown that constant noise above 55 dBA causes serious annoyance and above
50 dBA moderate annoyance at home (WHO, 2007). In a non-workplace and for
health and safety purposes, 55 dBA is set as a safety noise level for outside
and 45 dBA inside. Hospital and school permissible levels of noise are 35 dBA [1].
In Britain, the current and
advanced Ministry of Agriculture regulations established in January 2002 state
that propane cannons can be no closer than 150 metres
from residential areas, and 100 metres from other
kinds of noise makers. These machines generate noise at levels between 115 and
130 dB. At 100 meters the noise generated is above 80
dB, and greater than 75 dB at 150 metres, which is
much greater than specified safe levels for around the residence. In fact,
beyond 80 dB is near to the level at which ear protection should be used [3]. Noise beyond harmless levels leads to
numerous health impacts which include high blood pressure, annoyance, sleep
loss, stress, hearing impairment, loss of productivity and the ability to
concentrate, among others [2]. Hence, the study of noise is highly imperative so as to
create awareness on the impacts of noise on the environment for the betterment
of our society. In this research, the determination of actual distances for
installation of a 100 kVA non-sound proof power generator at residential areas
and the development of models for predicting and controlling environmental
noise pollution from this kind of generator shall be carried out. 2. MATERIALS AND METHODS 2.1. Physical Measurements All the noise measurements were made using the sound
level meter (SLM), modelWensnWS1361 with ½ inch electret condenser microphone.
This model has both A and C weightings and 0.1dB resolution with fast/slow
response. It has a measuring range 30 to 130 dBA or 35 to 130 dBC. Also, it is equipped with a built in calibration check
(94.0 dB) and tripod moving. It has an accuracy of ± 1.5 dB.
It has AC and DC outputs for frequency analyser level
recorder, Fast Fourier Transform (FFT) analyser,
graphic recorder and others. It also has electronic circuit and readout display
and a weight of 308 g. The microphone senses the small air pressure variations
related to sound and converts them into electrical forms. These signals are then passed to the
electronic circuitry of the instrument for processing. The readout displays the
processed sound levels in dB. The sound level meter
picks the sound pressure level at one instance in a certain location.
Measurements were taken by adjusting the sound level meter to A-weighting network
in all the sampling locations. The sound level meter was calibrated. The
manufacturer’s manual gave the calibration procedure. During the noise level
measurements, the microphone of the sound level meter was positioned at a
distance of above 5 m from the generator at a height of 1.2 m above the ground
and windshield was always used for accuracy. Slow response was used for
comparatively stable noise measurement. For instance, workplace noise level
measurements were taken on slow response. Here, the response rate is the time
period over which the instrument averages the sound level before displaying it
on the readout. Measurement of workplace sound pressure was made in the
uninterrupted noise field in the workplace, with the microphone located at the
position normally occupied by the ear exposed to the highest value of exposure
[14]. 2.2. Noise Level with Distance Measurements In this case, a workshop with a 100 kVA non-soundproof power generator was identified Measurements of noise levels from it as they vary with distance were taken. All noise level measurements were carried out using the sound level meter stated earlier, while distance measurements were made using a measuring tape. Lastly, Leqs for them were evaluated and the results are presented in section 3. 2.3. Calculating the Equivalent Continuous Noise
Level (LAeq) The LAeq is the steady noise level over a certain period of time that generates very similar quantity of A-weighted energy as the varying level over identical period. It is presented in equations (1-2) and it is measured in dBA. 1 2
T = time period over which LAeq is determined P(t) = the instantaneous A-weighted sound pressure Po = the reference sound pressures (20 μPa) Li = noise level in the ith sample Formula used for calculating the equivalent continuous noise level Leq of a noise source, N at a particular distance, x is presented in equation (3) [7]. 3 The noise level of a noise source, LN is presented in equation (4) [15]; [7] and [16] 4 Where, T =Time period over which Leq is determined ΔTN =Time period over which noise level of a noise source is measured ΔTB =Time period over which background noise level is measured LN =Noise level of a noise source in dBA LB =Background noise level in dBA LTOTAL =Total noise level in dBA. and, T = 5 minutes, ΔTN = 2 minutes, ΔTB = 3 minutes 2.4. Noise Modelling The data obtained were analysed and the linear regression method was used. Hence, linear fitting models were developed for it by using the relevant displayed parameters such as the maximum noise level of the generator, the attenuation coefficient and the coefficient of determination. Finally, a general model for evaluating, controlling and predicting environmental noise pollution from a source of this type was developed. The results are presented in sections 3. 3. RESULTS AND DISCUSSIONS 3.1. Analysis of Noise Levels and Distance
Measurements from A 100 kVA Non-Soundproof
Power Generator The results of the survey (Table 1 and Fig.1) show that
when the 100 kVA non-sound proof power
generator is put to use, the total noise level (noise level with generator) at
a distance of 65 metres is approximately equal to
55.4 dBA instead of a safety noise level of 55 dBA. This can cause serious
annoyance. Moderate annoyance can occur between 70 – 75 metres
if the generator is operated at night. Considering the Leq
the power generator adversely affects the residents up to distances of 55 metres with the Leq
approximate value of 55.34 dBA. Here, moderate annoyance may occur between
distances of 60 – 65 metres if the generator is
switched on at night. The levels of the background noise (from x = 5 metres
to x = 100 metres)
show that the area is conducive in the absence of the power generator. At a
distance of 65 m from the generator, the noise level of the generator is 55.34
dBA instead of the WHO tolerant level of 55 dBA for residential
areas. Table 1: Noise levels and distance measurements from a 100 kVA non-soundproof
power generator
Figure 1: A 100 kVA non-soundproof power
generator noise levels against distance Figure 2: The characteristics of the 100 kVA non-sound proof power generator measured noise level
Figure 3: The characteristics of the 100 kVA non-sound proof power generator modelled noise level
Figure 4: Comparism of
modelled noise levels, LG100(modelled) and measured noise levels, LG100(measured)
of a 100 kVA non-sound
proof power generator 3.2. Model Development for Noise Levels and
Distance Measurements of A 100 kVA Non-Sound Proof Power Generator The results of the analysis of a 100 kVA power generator noise levels, LG100 show that the noise levels of the power generator and distance, x are strongly correlated with the coefficient of determination, R2=0.99301. Hence, a linear fitting model in dBA for the generator noise levels is presented in equation (5). 5 Considering the error term, equation (5) becomes 6 In equation (5), if,
the noise level of the power generator at source is: 7 The intercept or the maximum noise level
(87.27031 dBA) has a standard error of 0.55303 dBA. The model has a slope of –0.47992
dBAm-1 with a standard error of 0.00923 dBAm-1. Comparing the measured noise levels, LG100(measured)
with its predicted noise levels of the power generator, LG100(modelled) (Table
2 and Figs. 2-4) show that there is no significant difference between them.
This simply shows that they are strongly correlated. Hence, equation (5) or (6)
is recommended to be used as a model for evaluating, predicting and controlling
environmental noise pollution from a noise source of this kind. The following
conditions satisfy the model presented as equation (5): ;
at ,
;
at ,
Condition (II) implies that the adverse effects
of the noise from the 100 kVA non-sound proof power generator cover
distances from 0 m (point of its installation) to 67 m. This is because at a
distance of 67 m from the power generator, its noise level is 55.11567 dBA
instead of the WHO tolerant level of 55 dBA for residential areas. The distance
at which the adverse effects covered is denoted by xc in metres. Condition (II)
means that the 100 kVA non-sound proof power generator should
be installed or sited from the residential area at a distance of 68 m and
above. This is because at the distance of 68 m, the noise level of the power
generator is 54.63575 dBA, which is less than the WHO recommended level of 55
dBA. Here, xs
is the distance it can be sited in metres (m). Table 2: Comparison of modelled noise levels, LG100(modelled) and measured noise levels, LG100(measured) of a 100 kVA non-sound proof power generator
3.3. Development of A General Model for
Evaluating, Predicting and Controlling Environmental Noise Pollution from A 100 kVA Non-Soundproof Power Generator Generally, it is observed that all the models developed in this work are of the forms in equation (8) and equation (9). 8 9 Where, is the slope representing the attenuation coefficient of the noise from the 100 kVA non-sound proof power generator and it is measured in dBAm-1. is the intercept or the maximum noise level signifying the noise level at source (i.e at x = 0) in dBA. x is the distance in metres (m) and is the coefficient of determination. Substituting equation (8) into equation (3), gives equation (10). 10 Equation (10) shows that when and for the 100 kVA non-soundproof power generator are known, Leq of the noise source can be determined at any distance, x with the consideration of the background noise level, LB at that point. Hence, with the introduction of the distance of measurement, x equation (10) can be used as a more scientific and reliable general model for evaluating, predicting and controlling environmental noise pollution from the 100 kVA non-soundproof power generator. Therefore, this model can be applied in environmental noise impact assessment. Leq is the equivalent continuous noise level. It is measured in dBA. 4. CONCLUSIONS AND RECOMMENDATIONS It is concluded from the findings that the maximum noise level the 100 kVA non-soundproof power generator is (87.27±0.55) dBA. The results indicate that the distances, xc in metres at which the adverse effects of the generator covered in the residential areas are are , while the corresponding distances, xs in metres in which it can be installed from the residential areas are . The results of the findings show that the models developed in this work can be used in evaluating and predicting the exact distance at which adverse effects of noise from this generator can cover and in controlling environmental noise pollution from a generator of this kind. The models require less cost, less manpower and less time than physical measurements. They can be used by the manufacturer of the generator to reduce its maximum noise level. Hence, the models are recommended to be used as reliable tools for environmental noise impact assessment as the results show insignificant difference between the measured noise levels, L(measured) and the modeled noise levels, L(modelled). ACKNOWLEDGEMENTS We
hereby thank all those who contributed in one way or the other for the success
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