摘要:
A frequency converter includes a symbol string editor in which the potential input symbols are grouped into at least two symbol lists. One of the lists is treated as a current symbol list, which can be scrolled and from which the symbols can be selected as the user input. In addition, a user is allowed to control change of the current symbol list such that the symbols in all of the symbol lists are available for selection. This arrangement allows for scrollable lists to be significantly shorter than a single list of potential symbols would be, which makes entering symbol strings faster.
摘要:
A method and arrangement of determining starting conditions of a solar converter in a photovoltaic system. The photovoltaic system includes a photovoltaic panel system having one or more photovoltaic panels. The method includes determining an open circuit voltage of the photovoltaic panel system, and determining beforehand limit values for the starting conditions, where the limit values include an open circuit voltage value and a temperature value, with which values the solar converter can be started. The method also includes determining beforehand the temperature dependency of the open circuit voltage of the panel system, determining a temperature of the panel system, and setting a criterion for starting the converter. The criterion includes determining, by using the determined temperature dependency and the determined limit values for the starting conditions, whether the determined temperature and the determined open circuit voltage enable the starting of the converter.
摘要:
A method includes selecting the branch of a ventilation system with the greatest pressure loss, opening a control valve in the selected branch and closing control valves in all other branches, controlling a fan to produce the desired air flow rate into the selected branch by using fan characteristic shaft power to air flow rate curves, and a shaft power estimate from the frequency converter and by adjusting the rotational speed of an electric motor to achieve the desired air flow rate, calculating the fan pressure corresponding to the desired air flow rate from fan characteristic fan pressure to air flow rate curves, saving the calculated fan pressure as a reference pressure, and adjusting the control valves in each of the remaining branches so that the desired air flow rate to each branch is delivered while the fan is controlled by the frequency converter to produce the reference pressure.
摘要:
An electronics compartment is disclosed with a component space which is sealed off from a surrounding environment by walls. An internal panel is arranged in the component space along a wall of the electronics compartment for delimiting an internal channel between the wall and the internal panel. An external panel is arranged along a same wall of the electronics compartment as the internal panel, but outside the component space for delimiting an external channel between the wall and the external panel. Air flowing in the internal channel and external channel can improve heat transfer through the wall, and cool electric components in the component space.
摘要:
An exemplary method and a control circuit are disclosed for controlling a power semiconductor component by producing a control signal (Ucin) for controlling the component, forming a second control signal (Ucout) in the potential of the controlled component from the control signal (Ucin), measuring a current flowing through the component, and comparing the measured current with a set limit. A fault signal (Ufault) having a logical state is provided on the basis of the comparison between the measured current and the set limit, producing a component control signal (Uave) from the fault signal (Ufault) and the second control signal (Ucout). If a fault is indicated, the component control signal has a value between high and low states, and otherwise the state of the component control signal (Uave) equals the state of the second control signal (Ucout).
摘要:
An enclosure for housing electrical equipment includes a bottom part, a wall part and a roof part. The bottom part, the wall part and the roof part define an interior chamber for housing the electrical equipment. The wall part includes at least one first air channel connected to the interior chamber, and the enclosure includes at least one fan for circulating air from inside the interior chamber through the at least one first air channel. The bottom part includes at least one second air channel connected to the interior chamber, and the enclosure includes at least one fan for circulating the air from inside the interior chamber through the at least one second air channel.
摘要:
A method and an arrangement are provided in connection with a photovoltaic power generator composed of series-connected photovoltaic modules. The method includes determining a maximum power point voltage (UMPP) and a maximum power point current (IMPP). The method also includes determining the ambient temperature (Tamb), calculating an estimated maximum power point voltage (Uest) by using maximum power point current (IMPP) and the determined ambient temperature (Tamb), comparing the estimated maximum power point voltage with the determined maximum power point (UMPP), and determining on the basis of the comparison whether the generator is operating under uniform conditions or in conditions with two maximum power points.