摘要:
The invention relates to a method for controlling a heatable dehumidifier. The heating of the dehumidifier is to be actuated only when several congruent time windows within which a temperature gradient is greater than or equal to 0 could be determined during a certain period of time, i.e. the heating is to be actuated only when no air flows into the interior of the expansion vessel of the transformer.
摘要:
A method for controlling the parallel running of a plurality of transformers T1, T2,…, TN) in a parallel circuit (10) is disclosed, wherein each of the transformers (T1, T2,…, TN) is assigned a measuring/control device (12) and all the measuring/control devices (12) are connected to one another via a communication connection (16). In the absence of a standby signal of at least one measuring/control device (12), interruption (16) of the communication (14) is displayed. The measured values determined at the time (t) of the interruption remain constant for the duration of the interruption (16) and are also included in the calculation of the control errors during the interruption (16), in order to minimise a circuit reactive current of the transformers (T1, T2,…, TN).
摘要:
A method for monitoring capacitor bushings (2a, 2b, 2c) for a three-phase AC system, wherein each capacitor bushing (2a, 2b, 2c) has a conductor (4), which is connected to one of the system lines (5a, 5b, 5c) of the AC system, and an electrically conductive lining (3) that surrounds the conductor (4), comprises the steps that – an upper capacitance (C0a, C0b, C0c) and a lower capacitance (C1a, C1b, C1c) are ascertained for each capacitor bushing (2a, 2b, 2c); – a measured voltage (U1a, U1b, U1c) is detected at each capacitor bushing (2a, 2b, 2c), which measured voltage is present between the respective lining (3) and an earth potential (13); – an actual capacitance (C0a', C0b', C0c') is computed for each capacitor bushing (2a, 2b, 2c), which actual capacitance is dependent on the respective measured voltage (U1a, U1b, U1c), the respective lower capacitance (C1a, C1b, C1c) and on the measured voltage (U1b, U1c, U1a), the lower capacitance (C1b, C1c, C1a) and the upper capacitance (C0b, C0c, C0a) of one of the other capacitor bushings (2a, 2b, 2c); the respective upper capacitance (C0a, C0b, C0c) is compared with the respective actual capacitance (C0a', C0b', C0c') for each capacitor bushing (2a, 2b, 2c); a monitoring signal is produced that is dependent on the results of the capacitance comparisons.
摘要:
The invention relates to a device and method for controlling an electric arc furnace (10) in the initial phase of a melting process. A sensor (16) for measuring the actual current and a sensor (15) for measuring the actual flowing current are provided in each branch (7) of the electric arc furnace (10). The actual impedance (Z actual ) is calculated time-dependently by means of the control and regulating unit (30). A load tap changer (20) is associated with a furnace transformer (6) having a primary side (6P) and a secondary side (6S), said load tap changer (20) being embodied as a semi-conductor step switch. Said semiconductor step switch (20) carries out a clock pulse rate of several milliseconds.
摘要:
The invention relates to a control transformer, designed as a phase-shifting transformer, wherein semiconductor switching elements are provided for each phase on a control winding (2, W1, W2, W3) having a plurality of partial windings (W1, W2, W3). According to the invention, in each phase (U, V, W) an additional connecting line (L1, L2) with an additional switching element (S1, S2) is provided, wherein each of said connecting lines connects a module (M3) of the respective phase to the end of the main winding (2) of the adjacent phase.
摘要:
The invention relates to a method for dehumidifying air and to an air dehumidifier. To this end, a filter element is provided that is filled with granular material that can be regenerated by baking out. For effecting this baking out, a heating device is provided that is only actuated when both a humidity sensor indicates that a humidity limit value has been exceeded as well as a relative pressure sensor or a comparable technical means indicates that, at the moment, no flow toward the oil expansion tank is recorded.