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HUFNAGL, E., AIGNER, M., SCHMAUTZER, E.
EVALUATION OF AN URBAN MEDIUM VOLTAGE NETWORK USING RELIABILITY INDICES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 26
This article deals with the assessment of reliability indices of a medium voltage network. In order to evaluate an urban medium voltage network, several steps can be taken to determine the reliability indices describing the network in its current state, as well as for potential changes caused by e.g. reinforcement of the electrical installation, restructuring measures, increased generation and demand in the network structure. To successfully conduct the following calculations, the correct use of the input data for the created reliability datatypes and reliability values is essential. By using reliability indices an impartial comparison between various options (referring to the cited measures) is possible.
MALLITS, T., SCHMAUTZER, E., FICKERT, L.
REFLECTIONS ON GLOBAL EARTHING SYSTEMS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 28
On the basis of measurements it can be shown that only a portion of the phase to ground fault current enters the physical soil. Therefore the earth potential rise (EPR) is considerably decreased and the contact voltages become much lower than those determined by the usual approaches. A risk assessment method used in the UK and Australia is presented by which the corrective actions in the case of dangerous contact voltage can be determined.
HUFNAGL, E., FICKERT, L., SCHMAUTZER, E.
EFFICIENT CALCULATION OF EARTH FAULT CURRENTS IN COMPENSATED NETWORKS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 29
In this paper, a simplified approach for determining the ground fault currents is presented which is specifically useful in compensated systems. In this case, due to the estimation of the relative magnitudes of the equipment parameters, the equivalent circuit in symmetrical components of the single-pole fault is significantly reduced. Thus the electrical parameters of the impedances can be directly used.
SCHMAUTZER, E., PACK, S.
NEW WAYS TO INTEGRATE GROUNDING, EQUIPOTENTIAL BONDING, SHIELDING AND LIGHTNING PROTECTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 14
The safe and reliable operation of electronic equipment in modern low-voltage electrical, suitable for bidirectional energy and information flows, requires - starting from the transformer stations via the mains connection to the location of the equipment in the buildings - special attention with regard to the integration of grounding, equipotential bonding, shielding and lightning protection. As these themes so far in the planning, implementation and verification are considered mostly separately, in practice a variety of electro technical problems such as with stray currents, unwanted interference fields and inductive interference caused by low-frequency and transient currents result. In the following article new and old methods for a functional, comprehensive approach to planning and construction of electrical installations are combined, which takes into account the needs of various grid-bound supply systems such as electricity, gas, water and telecommunications.
AIGNER, M., RAUNIG, C., SCHMAUTZER, E., FICKERT, L.
SMART GRIDS – CONSIDERATIONS REGARDING PROTECTION OF ELECTRICAL INSTALLATIONS AND SAFETY IN CASE OF DECENTRALIZED POWER SUPPLY
KOMUNALNA ENERGETIKA / POWER ENGINERING, 19
Parallel to the progress of information- and communication technology in recent years, energy production and energy distribution get more economic and efficient; so called Smart Grids get more attention. The focus of the Smart Grid infrastructure lies in the increased involvement of decentralized power generation, exemplarily photovoltaic plants, small hydro power generators or stirling engines in the low-voltage or medium-voltage network. Due to the increased integration of distributed (renewable) energy generation systems, a significant contribution concerning the reduction of CO2 emissions claimed in the 20-20-20 targets and transmission losses is provided.
An important advantage of Smart Grids is the possibility of a multivalent up to a fully independent power supply for islanded grids and microgrids. In case of a failing (separation from the distribution network) a certain degree of power can be principally maintained by decentralized feed-in. Short circuit currents from distribution transformers and additional short circuit currents from decentralized sources (bidirectional current flow) can lead to a incompatibility with existing protection systems.
Therefore the increased integration of decentralized generation requires new considerations regarding protection systems in terms of personal safety and safety of electrical equipment.
The neutral point treatment of decentralized sources, transformers and uninterrupted supply units in combination with distribution transformer is important for security of networks and personal safety.
This paper shows exemplary the effects of a missing neutral point to earth connection (earthing) of decentralized generators in case of parallel supply.
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