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MSU ECE 4512 - DESIGN CONSTRAINTS

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2. DESIGN CONSTRAINTS An effective animal deterrent device that is tailored for gang operated air break (GOAB) switches in high voltage applications is a desired technology for power utility companies. The proposed project is both a practical and marketable concept. In order to design an effective animal deterrent device, many design constraints must be developed and followed. Table 1 and table 2 itemize the most significant technical and practical design constraints, respectively. 2.1 TECHNICAL DESIGN CONSTRAINTS TABLE 1: Technical Design Constraints Name Description Motion Sensor Adjustable sensitivity and distance 180o horizontal viewing angle per sensor Audio Response Operating Range – 10 kHz and 40 kHz Signal-to-Noise Ratio – at least 90 dB Lighting Light intensity ~30 Joules 1 million strobes per lifetime Adaptability Programmable to operate in several regions Power Regulation Survive moderate spikes in voltage/current 2.1.1 MOTION SENSOR The proposed device will use infrared motion sensors to turn itself on. Once the device has been triggered by a rapid change in heat within the motion sensors’ target area it will remain active for 8 to 10 seconds and then shutdown. The motion sensor is a vital part of the design, because it allows the device to remain silent until an animal is in the coverage area. The motion sensors have a horizontal viewing angle of 180o and are mounted on opposite sides from each other providing a dual coverage area. This provides the device with a 360o total viewing angle in the direction of the approaching power lines as shown in figure 1. Having dual coverage is ideal for the detection of animals such as squirrels that use the power lines to travel back and forth from nesting to feeding areas. It will also be effective against birds that approach the power lines from the air. The motion sensors will be capable of horizontal and vertical adjustment allowing the user of the device to target a specific area. This is an important feature, because the area where the animals access the energized equipment may be an adjacent tree or structure out of the power line approach area. The distance sensitivity of the motion sensors is triggered within a 30 foot radius of the sensor, thus providing approximately 2827 square feet of coverage area. These combined traits make the motion sensor detection system one of the key features of this device. FIGURE 1: Motion Sensor Coverage Area2.1.2 AUDIO RESPONSE The audio output is one of the deterring features for successful animal mitigation in our design. This segment of the design utilizes an audio integrated circuit chip with a biasing circuit to operate between 8 kHz (kilohertz) and 40 kHz. The human hearing range is between 20 Hz and 20 kHz; therefore it will operate in the upper audible and lower ultrasonic range [1]. This range was chosen in order to successfully deter squirrels and birds. Squirrels have a hearing range from 113 Hz to 49 kHz with highest sensitivity at 8 kHz, while birds operate between 10 Hz to 40 kHz [2]. This is outside of the most sensitive human hearing range of 1 kHz to 4 kHz [1]. The selected frequency range should be the best balance of effectiveness and toleration, because it targets the animal's most sensitive hearing range while avoiding human's most sensitive range. 2.1.3 LIGHTING RESPONSE The lighting output is the visual deterrent feature of the device. It consists of a strobing Xenon light to reinforce the audio output. The Xenon tube has an expected lifetime of 1 million strobes per bulb. The strobe light will flash at a frequency of 8 times per second. Therefore, if the animal deterrent device were triggered 20 times a day the bulb would strobe 160 times a day and have a life expectancy of over 17 years. Even if the animal deterrent device was triggered more frequently, the life of the bulb would be well within the time frame of the preventive maintenance schedule. The light intensity is calculated to emit approximately 40 watts per flash [3]. At a flash rate of 8 times per second the output would be a total of 320 watts per second. This equates to one flash, which is on only 1/16th of a second. The power output in one second is the equivalent of four stoplights. This is enough to be noticeable yet not totally disturbing to the surrounding area. 2.1.4 ADAPTABILITY For an animal deterrent to be successful and capture enough of the market to remain in production, it must be capable of being modified to fit the intended purpose of its user in different regions of the country. For example, the Richardson ground squirrel found in the Midwest part of the U.S. can hear sounds up to 49 kHz, while grey squirrels found in the South and Eastern part of the U.S cannot hear any sounds over 40 KHz. Employing this type of information into the sound scheme of an electronic animal deterrent is imperative to its success. In addition to frequency range different animals have different predators. The ability to program specific predators’ noises and target certain frequencies adds a new dimension to the proposed animal deterrent that no other animal deterrents offer. This capability will allow utility companies to tailor the sounds emitted from the device to the animal that is causing problems in their area. 2.1.5 POWER REGULATION The proposed animal deterrent device will be mounted within 2 meters of the high-voltage switches it will protect. These switches are located either on a utility pole or in a substation and both places are very susceptible to lighting. Lighting can inject several hundred thousand volts into the power grid in less than ½ second [4]. For this reason transient voltage suppressors will be used to minimize damage to the power supply and internal circuitry of the animal deterrent. Transient voltage suppressors are a unique type of diode device designed to absorb large quantities of power very quickly. Although nothing will protect against a direct lighting strike, the transient voltage suppressor’s 1 micro second response time and 600 watt dissipation capability will provide over voltage and over current protection to the device. Each transient voltage suppressors will be rated to bias and discharge any voltage 20 percent over the rated rail voltage. For example, the 5 volt rail of the circuit will have a transient voltage suppressors rated at 6 volts connected between it and ground. Anything over 6 volts will


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