RCDD Chapter 2

When devices or systems share a common electromagnetic environment and their frequencies for operation overlap, electromagnetic interference (EMI) occurs. EMI refers to the disturbance caused by electromagnetic radiation emitted from one electronic device affecting the performance of another device. This interference can lead to malfunctions, signal degradation, or complete failure of the affected device. Therefore, it is crucial to implement proper electromagnetic compatibility (EMC) measures to minimize EMI and ensure the smooth operation of devices in a shared electromagnetic environment.

The given correct answer is "EM spectrum". The question asks for the collective term for various types of electromagnetic waves such as light, radio waves, microwaves, infrared radiation, ultraviolet rays, X-rays, and gamma rays. These waves collectively form the electromagnetic spectrum, which encompasses the entire range of electromagnetic radiation.

EM fields, or electromagnetic fields, can have both positive and negative effects depending on their interaction with the network or electronic devices. If the EM fields interfere with the operation of the network or devices, they can be undesirable as they may cause disruptions or malfunctions. However, if the EM fields are properly managed and do not interfere with the operation, they can be desirable as they can be used for various purposes such as wireless communication or power transmission. Therefore, the statement that EM fields can be both desirable and undesirable is true.

Magnetic beads are commonly used for filtering purposes due to their magnetic properties. These beads can be easily manipulated and separated from a solution using a magnetic field. In many cases, a single bead may not be sufficient for the desired filtration process, hence requiring the use of multiple beads. Therefore, it is true that more than one bead may be required when using magnetic beads for filtering.

The statement is true because an unwanted signal can indeed be comprised of two components: common mode (CM) unwanted signal and differential mode (DM) unwanted signal. Common mode refers to the unwanted signal that appears in phase and with the same amplitude on both signal lines, while differential mode refers to the unwanted signal that appears with opposite phase and equal amplitude on both signal lines. Therefore, both CM and DM components contribute to the overall unwanted signal.

Placing telecommunications systems next to equipment that can generate EMI (Electromagnetic Interference) is not advisable. EMI can disrupt the functioning of telecommunications systems, leading to poor signal quality and communication issues. To ensure optimal performance and minimize interference, it is recommended to keep telecommunication systems away from EMI sources.

EMC stands for Electromagnetic Compatibility, which refers to the ability of a device or system to function without error in its intended electromagnetic environment. This means that the device or system is designed and engineered to operate effectively and without interference from electromagnetic radiation or other electromagnetic sources. It ensures that the device or system does not emit excessive electromagnetic radiation that could interfere with other devices or systems nearby. In addition, it also ensures that the device or system is immune to electromagnetic interference from other sources, allowing it to operate correctly in its intended environment.

EMI stands for Electromagnetic Interference, which refers to the disturbance caused by electromagnetic radiation from electronic devices. This interference can occur naturally, such as from lightning or cosmic radiation, or it can be man-made, such as from power lines or electronic devices. Therefore, EMI can be both man-made and naturally occurring.

This statement is true because electromagnetic interference (EMI) can disrupt the functioning of electronic devices, including the autohelm system of a boat. When a cellular telephone is in use, it emits electromagnetic radiation that can interfere with the autohelm's sensors and cause it to steer the boat off course. This is a physical evidence of the effects of EMI on the boat's steering system.

Common Mode (CD) and Differential Mode (DM) are two types of unwanted signals that can occur on a cable. Common Mode signals refer to noise or interference that is present on both the signal and ground lines of the cable, while Differential Mode signals refer to noise or interference that is present between the signal and ground lines. Both types of unwanted signals can degrade the quality of the desired signal and cause errors or disruptions in communication.

EMC, which stands for Electromagnetic Compatibility, refers to the ability of electronic devices to operate without interference or causing interference to other devices in their electromagnetic environment. It ensures a level playing field by minimizing unwanted signals, such as electromagnetic interference (EMI), that can disrupt the proper functioning of electronic devices. Therefore, the statement "EMC may be interpreted as a level playing field for electronic unwanted signals" is true.

In this question, the correct answer is "Common Mode." Common mode refers to unwanted signals that appear in both the positive and negative terminals of a circuit or system. These signals are typically caused by external interference or noise. The other option, "Differential Mode," refers to unwanted signals that appear between the positive and negative terminals of a circuit or system. However, the question asks which one predominates, and the correct answer is common mode, indicating that common mode signals are more prevalent than differential mode signals.

The statement is true because screened or foil twisted-pair cables, also known as ScTP or FTP cables, have similar considerations as balanced twisted-pair cables when it comes to unwanted signal coupling. This means that the same factors that affect the interference and signal quality in balanced twisted-pair cables, such as crosstalk and electromagnetic interference, also apply to ScTP or FTP cables. Therefore, it is important to take these considerations into account when using screened or foil twisted-pair cables to ensure optimal performance and minimize signal interference.

The explanation for the given correct answer is not available as the question and options provided are incomplete and unclear.

The correct answer is "All of the above" because the question asks for the methods of coupling electromagnetic energy from a source to a receptor, and all four categories mentioned (conducted, inductively coupled, capacitively coupled, and radiated) are valid methods of coupling electromagnetic energy.

The question is asking for the three types of a certain phenomenon. The correct answer is ESD (Electrostatic discharge). This is supported by the fact that the question mentions "Discharge through a spark in the air" and "Contact discharge" as two types, which are both associated with electrostatic discharge. Therefore, the correct answer is ESD.

The correct answer is Volts per meter (V/m). Radiated emissions are measured by determining the field strength of the outgoing radiation. The unit of measure for this field strength is volts per meter, which represents the electric field strength at a given distance from the source of radiation. This unit helps to quantify the intensity of radiated emissions and assess their potential impact on nearby electronic devices or systems.

Visible light represents only a small portion of the electromagnetic (EM) spectrum. The EM spectrum includes a wide range of electromagnetic waves, from radio waves to gamma rays. Visible light specifically refers to the wavelengths of electromagnetic radiation that are visible to the human eye, ranging from approximately 400 to 700 nanometers. While visible light is important for human vision and is commonly encountered in everyday life, it is just a small fraction of the entire EM spectrum.

LCTL in db is a measure of the conversion from common mode to differential mode unwanted signal due to cabling imbalance. This means that it quantifies the loss of signal quality when a common mode signal is converted into a differential mode signal due to an imbalance in the cabling.

The correct answer includes three essential elements to any EMC problem. These elements are the source of an electromagnetic phenomenon, the receptor (or victim) that cannot function properly due to the electromagnetic phenomenon, and a path between them that allows the source to interfere with the receptor. These elements are necessary for an EMC problem to occur and must be considered when analyzing and addressing such problems.

The given answer states that there is no specific technique or unit to measure EMC. This implies that EMC (Electromagnetic Compatibility) cannot be measured using a specific technique or unit.

The statement is true because the responsibility for the Electromagnetic Compatibility (EMC) of Intelligent Transportation Systems (ITS) does not lie directly with the designer. EMC is typically the responsibility of the system integrator or the manufacturer who ensures that the various components and systems within the ITS operate harmoniously without causing electromagnetic interference or being susceptible to it. The designer's role is to create the design and specifications for the ITS, but the actual implementation and compliance with EMC standards are usually handled by other parties.

The statement is incorrect. The EM energy generated by equipment is commonly referred to as emissions, not immunity. The equipment's ability to withstand EM disturbances is referred to as immunity, not emissions.

This statement suggests that all electromagnetic interference (EMI) problems can be explained using the fundamental laws of physics, and that EMI problems are always related to circuits. This implies that any EMI issue can be resolved by understanding the underlying physics principles and analyzing the circuit involved. Therefore, the statement is true.

To avoid problems with conductive ground loops, the potential difference between the two grounds should be kept as low as possible. A potential difference of 1.0 V root mean square is recommended to prevent any interference or issues caused by ground loops. This ensures that there is minimal voltage difference between the two grounds, reducing the chances of current flow and potential noise or signal distortion.

EMI problems in telecommunications systems can only occur when there is a coupling path between the interfering source and the susceptible unit. This means that there must be a physical or electromagnetic connection between the source of interference and the device that is susceptible to the interference. Additionally, there must be an interfering source present, which could be any device or component that emits electromagnetic radiation. Finally, there must be a susceptible unit, which refers to any device or component that is sensitive to electromagnetic interference. All three of these conditions must be met for EMI problems to occur in telecommunications systems.

The "Site issue" that goes along with the statement in parentheses is the lack of ac surge protection devices in commercial and standby electrical service entrances. This means that there is no protection against power surges or electrical interference at the point where the electrical service enters the building. Without these surge protection devices, the electrical equipment and systems within the building are more vulnerable to damage from power surges, which can lead to equipment failure and downtime.

The coupling from mutual impedance between the electrical power and telephone facility is primarily determined by physical separation, length of exposure, resistance of the return path, and shielding effectiveness. Signal injectors do not directly contribute to the coupling between the two facilities.

Electostatic discharge is not a source of internal EMI. EMI stands for electromagnetic interference, which refers to the disturbance caused by electromagnetic radiation from external sources. Electostatic discharge, on the other hand, is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or a dielectric breakdown. While it can cause interference in electronic devices, it is not considered a source of internal EMI.

The statement is false because it is possible to reduce emissions at the source of internal EMI sources. Internal EMI sources refer to electromagnetic interference generated within a device or system. While it may be more challenging to control internal EMI compared to external sources, it is still possible to implement measures such as shielding, grounding, and filtering to reduce emissions at the source. These techniques help to minimize the generation and propagation of electromagnetic interference within the device or system, improving its overall electromagnetic compatibility.

Radiated interference can enter electronic devices through various means, including missing or inadequate enclosures, missing or inadequate device shielding, and signal lines and proximity to radio frequency (RF) sources. These factors can allow external electromagnetic waves to penetrate the device and interfere with its proper functioning.

External EMI sources typically include cellular phones, electrical power cables, rectifiers, and radios. These sources emit electromagnetic interference which can disrupt the functioning of electronic devices. Cellular phones, in particular, emit radio waves that can interfere with nearby electronic equipment. Therefore, cellular phones are considered one of the external sources of EMI.

Radio Frequency Immunity is generally stated at 3 volts root-mean-spuare (Vrms).

The grounding electrode conductor is responsible for grounding the electrical power at the services entrance. It is a conductor that connects the grounding electrode (such as a metal rod or plate) to the electrical system's main grounding busbar. This conductor helps to provide a path for electrical faults or surges to safely dissipate into the ground, protecting the electrical system and preventing damage or hazards.

The major components that do not belong when dealing with electromagnetically induced interference are the "Balanced DM field of the electrical power system." Electromagnetic interference refers to the disturbance caused by electromagnetic radiation on electronic devices or systems. Unbalanced EM fields of the electrical power system, coupling between the electrical power and telecommunications systems, and the susceptibility of the telecommunications systems are all relevant factors in understanding and addressing this interference. However, the concept of a "Balanced DM field" is not commonly associated with electromagnetically induced interference.

Common mode unwanted signals on cabling can affect equipment in two ways. Firstly, they can corrupt transmitted signals on a balanced circuit, leading to signal distortion or loss of data. Secondly, these unwanted signals can be converted to a differential mode (DM) signal by the cable or equipment, causing interference and disrupting the proper functioning of the equipment. This interference can directly affect equipment operation, such as causing a computer to lock up or malfunction.

The sources of unwanted signal include electrical power converters, logic circuits, other internal unwanted signals, electrical power lines, and cabling. These sources can introduce noise or interference into a system, affecting its performance and causing undesired effects.

The statement is false because the wavelength of an electromagnetic wave is inversely related to its frequency. This means that as the frequency of the wave increases, the wavelength decreases, and vice versa. This relationship is described by the equation c = λν, where c is the speed of light, λ is the wavelength, and ν is the frequency. Therefore, the correct answer is false.

Conducted interference primarily enters electronic devices through input signal lines, output signal lines, and electrical power cords. Input signal lines carry signals from external sources into the device, making them susceptible to interference. Output signal lines transmit signals from the device to external components, which can also be affected by interference. Electrical power cords supply power to the device, and any interference present in the power supply can enter the device and affect its performance.

The recommendation is to use an overall longitudinal balance of 60db or greater at low frequencies. This means that the balance between the left and right channels should be 60db or more, ensuring that the sound is evenly distributed and there is no imbalance between the two channels. This is particularly important at low frequencies, as any imbalance can result in a distorted or uneven sound output. Therefore, a balance of 60db or greater is recommended to ensure optimal audio quality.

Adding a CM choke in series with the transformer improves the CM rejection of the magnetics in balanced twisted pair cabling. A higher CMRR (Common-Mode Rejection Ratio) is desirable for high-quality magnetics to effectively reject common-mode noise over the operating frequency range of interest. Therefore, a minimum CMRR of 40 dB is desirable.

The example threshold values for EM field strength immunity are 3 V/m, 5 V/m, and sometimes 10 V/m. These values represent the minimum levels of electromagnetic field strength that a device or system can withstand without experiencing any adverse effects. The "sometimes" indicates that the threshold of 10 V/m may not always apply and could vary depending on specific circumstances.

Man-made sources of EMI include conversion (step up/down), distribution (insulator, cabling, transformers, or grounding), and generators. These sources can emit electromagnetic interference due to the electrical processes involved in converting or distributing power. Conversion processes, such as step up/down transformers, can generate EMI as a byproduct. Distribution systems, including insulators, cables, transformers, or grounding, can also produce EMI due to the electrical currents passing through them. Additionally, generators, which are used to produce electrical power, can generate EMI as a result of their operation.

DM noise does not primarily affect equipment by corrupting transmitted signals on an unbalanced circuit. DM noise, also known as common-mode noise, is a type of electromagnetic interference that affects both the signal and ground lines of a balanced circuit. It causes interference by inducing noise voltages that are common to both the signal and ground lines, resulting in signal degradation. Therefore, the given statement is false.

The correct answer is a list of factors that can contribute to site issues such as telephone distribution. Unbalanced cabling can cause interference and signal degradation. Incorrect or missing primary protectors can leave the system vulnerable to power surges. Incompatible secondary protectors may not effectively filter out unwanted noise. Incorrect or missing grounds can lead to electrical faults. Incorrect or missing connections can result in poor signal quality or loss of connectivity. All of these factors can contribute to site issues with telephone distribution.

The specified severity levels for strengths when testing equipment for immunity to radiated fields from 30MHz to 1 GHz are 1 V/m, 3 V/m (which is considered a moderate environment), and 10 V/m.