Crosstalk is defined as an unwanted coupling between the conductors. By this it is meant that signals from one of the signal conductors (a generator in this case) are coupled to another signal conductor (receptor), or conductors (receptors), depending on the number of conductors in the vicinity of the generator. Crosstalk in this way affects the signal level on the receptor and thereby affects the total system performance within the system. This can happen in several ways, one of which is through edge coupling. Edge coupling is a process where two signal conductors are placed beside each other in the same layer while the ground conductor could have been placed either under these conductors, in a separate layer like Mclin (Microstrip coupled lines) and Sclin (Coupled striplines), or beside the signal conductors as in Cpwcpl2 (Coplanar wave guide coupled lines). This then means that edge coupling occurs through the sides where the generator and the receptor are facing each other. Broadside coupling is another way, where it occurs when the signal conductors are broadside faced to each other in different layers with reference planes above and below these signal conductors. Coupling of the signals from the generator to the receptor can occur through capacitive coupling or inductive coupling. Capacitive coupling, also known as electrical coupling, occurs due to the difference in the characteristic impedance of the generator (usually 50 or 100 §Ù) and its heavy load (1 k§Ù or more) which results in high voltage difference between the generator and the reference conductor (ground). This leads to the creation of a charge across the generator and the receptor-facing sides and finally results in the electric field coupling between them. On the other hand, inductive coupling, also known as magnetic coupling, occurs when the load is less than the characteristic impedance of the generator, and this thereby results in a heavy current flow through the generator which in return results in a strong magnetic field around itself and so leads to magnetic coupling to the receptor. The aim in this thesis is to measure both the capacitive and inductive coupling load¡¯s impacts on both the edge coupling and the broadside coupling models through crosstalk on the receptor. This thesis starts with the background and corresponding theory and equations to the crosstalk coupling. Later on it tests both the edge- and broadside coupling models with different physical properties exploitation. Inductive and capacitive loads are used to measure the resulting crosstalk coupling. Particularly to see the effect of capacitive and inductive coupling in reality in multi layered PCB, a Sbclin (Broadside coupled striplines) model has been used with different angular placement of the generator. Finally mclin physical models are compared with the simulated models and corresponding differences are discussed. It can be concluded that crosstalk effect increases or decreases with physical properties exploitation. Crosstalk also increases with the wrong termination of the load.

In some electrical facilities for underground mining, IT-system grounding is used for processes of high priority. This report explains why such systems are used in these kinds of environments, what happens when single-line-ground faults occur and how does the fault protection and monitoring devices handle those faults in accordance to current regulations and standards.An IT-system imply that the neutral point of a transformer is completely or partially connected to earth and exposed conductive parts are bolted directly to ground.IT-coupled networks have been implemented in some mining industries to prevent long and unnecessary down time of production. This is achieved by allowing a single-line-ground fault without interfering with the operation. According to current regulations and standards a single-line-ground fault is allowed on the term that continuously monitoring the insulation of the system, alarm in presence of a fault and remedy as soon as possible.During a single-line-ground fault the artificial neutral point of the system will be displaced relative earth and different amounts depending on the resistance in the fault location. When a bolted single-line-ground fault occur, the faulty line will adopt earth-potential. Between a healthy line and earth, the potential difference reaches line-line voltage and even more than that, depending on the fault-resistance. This entails a higher requirement of the insulation level of the equipment installed in an IT-system. The fault current that emerges in an IT-system depends especially of the capacitive connection between the line conductors and earth, but it is reduced by the resistance in the fault location.In the existing electrical system of the underground mine, insulation-monitoring-devices where installed. These where setup with two alarm limits, one for alarming and the second for release of the circuit breaker feeding the main busbar, if the fault remains for longer than two hours.The insulation monitoring in the existing electrical system, where supplemented with residual-current-monitoring, setup to alarm for residual currents exceeding 60 mA. One presumption the residual-current-monitoring devices requires to be able to detect a fault, is that the upstream installed cable network is widespread enough, that the capacitive connection causes a big enough current to flow.In this report the characteristics of an IT-network were verified with calculations. Simple calculations of the minimum cable length were also made, when using residual-current-monitoring.The conclusion for the existing electrical system in the underground mine, is that the IT-system network of it, is installed in accordance with current regulations and standards in Sweden.